| Mechanism: | Type 2 diabetes mellitus is a widespread disease, affecting millions of people globally. Although genetics and environmental factors seem to have a role, the cause of this metabolic disorder is largely unknown. Here we report a genetic flaw that markedly reduced the intracellular expression of the high mobility group A1 (HMGA1) protein, and adversely affected insulin receptor expression in cells and tissues from four subjects with insulin resistance and type 2 diabetes. Restoration of HMGA1 protein expression in subjects' cells enhanced INSR gene transcription, and restored cell-surface insulin receptor protein expression and insulin-binding capacity. Loss of Hmga1 expression, induced in mice by disrupting the Hmga1 gene, considerably decreased insulin receptor expression in the major targets of insulin action, largely impaired insulin signaling and severely reduced insulin secretion, causing a phenotype characteristic of human type 2 diabetes.; Increased levels of IL-6 add further risk to the impact of obesity in respect to the development of type 2 diabetes mellitus (T2DM). A C-174G polymorphism within the IL-6 promoter region was shown to influence transcription rate of IL-6. We made use of a nested case-control study within the European Prospective Investigation into Cancer and Nutrition-Potsdam cohort of 27,548 individuals, selecting 188 T2DM cases and 376 controls to investigate this polymorphism in respect to development of T2DM. This polymorphism was found to modify the correlation between body mass index (BMI) and IL-6 by showing a much stronger increase of IL-6 at increased BMI for CC genotypes compared with GG genotypes. Interestingly, C-174G polymorphism was found to be an effect modifier for the impact of BMI regarding T2DM. Whereas BMI greater than or equal to 28 kg/m(2) increased the risk of T2DM 3.44-fold [95% confidence interval (CI), 1.34- to 8.24-fold] for GG genotypes and 2.94-fold (95% CI, 1.56- to 5.56-fold) for GC genotypes, we found a 17.68-fold (95% CI, 3.57- to 87.66-fold) increase in risk for CC genotypes. In conclusion, obese individuals with BMI greater than or equal to 28 kg/m(2) carrying the CC genotype showed a more than 5-fold increased risk of developing T2DM compared with the remaining genotypes and, hence, might profit most from weight reduction.; The insulin receptor substrate-2 (IRS-2) is a major insulin signalling molecule. IRS-2 inactivation in mice induces a form of diabetes characterized by peripheral insulin resistance and reduced beta cell mass. We tested the hypothesis that a common non-conservative amino acid substitution of IRS-2 (G1057D) might interact with overweight in the pathogenesis of type 2 diabetes. The variant was genotyped in 193 Italian patients with type 2 diabetes and 206 control subjects. In the absence of overweight, the risk of type 2 diabetes decreased according to the dosage of the D1057 allele (odds ratio for GD genotype 0.46 [95% CI 0.25-0.86]; DD genotype 0.18 [0.04-0.68]; P for trend = 0.0012). Conversely, the interaction between overweight and genotype increased the risk of type 2 diabetes according to the dosage of the D1057 allele (odds ratio for GD genotype 2.50 [1.11-5.65]; DD genotype 5.74 [1.11-29. 78]; P for trend = 0.0047). Among controls, fasting C-peptide levels, after adjustment for plasma glucose, were inversely related to the dosage of the D1057 allele (P = 0.020). This finding suggested that carriers of the D1057 allele may have higher insulin sensitivity and supported the protective effect of this allele. Conversely, among overweight patients there was a parallel increase in fasting plasma glucose (P for trend = 0.037) and fasting C-peptide according to the dosage of the D1057 allele, suggesting that higher insulin resistance and relative beta cell failure contributed to the increased risk of type 2 diabetes in overweight carriers of this allele. These data provide evidence for a strong association between type 2 diabetes and the G1057D common genetic variant of IRS-2, which appears to be protective against type 2 diabetes in a codominant fashion. Overweight appears to modify the effect of this polymorphism toward a higher risk of type 2 diabetes. Carriers of this polymorphism may represent an elective target for prevention of type 2 diabetes through preventing or treating excessive weight.; Genome-wide association studies have revealed that common noncoding variants in MTNR1B (encoding melatonin receptor 1B, also known as MT(2)) increase type 2 diabetes (T2D) risk(1,2). Although the strongest association signal was highly significant (P < 1 × 10(-20)), its contribution to T2D risk was modest (odds ratio (OR) of ∼1.10-1.15)(1-3). We performed large-scale exon resequencing in 7,632 Europeans, including 2,186 individuals with T2D, and identified 40 nonsynonymous variants, including 36 very rare variants (minor allele frequency (MAF) <0.1%), associated with T2D (OR = 3.31, 95% confidence interval (CI) = 1.78-6.18; P = 1.64 × 10(-4)). A four-tiered functional investigation of all 40 mutants revealed that 14 were non-functional and rare (MAF < 1%), and 4 were very rare with complete loss of melatonin binding and signaling capabilities. Among the very rare variants, the partial- or total-loss-of-function variants but not the neutral ones contributed to T2D (OR = 5.67, CI = 2.17-14.82; P = 4.09 × 10(-4)). Genotyping the four complete loss-of-function variants in 11,854 additional individuals revealed their association with T2D risk (8,153 individuals with T2D and 10,100 controls; OR = 3.88, CI = 1.49-10.07; P = 5.37 × 10(-3)). This study establishes a firm functional link between MTNR1B and T2D risk.; The molecular mechanisms involved in the development of type 2 diabetes are poorly understood. Starting from genome-wide genotype data for 1924 diabetic cases and 2938 population controls generated by the Wellcome Trust Case Control Consortium, we set out to detect replicated diabetes association signals through analysis of 3757 additional cases and 5346 controls and by integration of our findings with equivalent data from other international consortia. We detected diabetes susceptibility loci in and around the genes CDKAL1, CDKN2A/CDKN2B, and IGF2BP2 and confirmed the recently described associations at HHEX/IDE and SLC30A8. Our findings provide insight into the genetic architecture of type 2 diabetes, emphasizing the contribution of multiple variants of modest effect. The regions identified underscore the importance of pathways influencing pancreatic beta cell development and function in the etiology of type 2 diabetes.; Identifying the genetic variants that increase the risk of type 2 diabetes (T2D) in humans has been a formidable challenge. Adopting a genome-wide association strategy, we genotyped 1161 Finnish T2D cases and 1174 Finnish normal glucose-tolerant (NGT) controls with >315,000 single-nucleotide polymorphisms (SNPs) and imputed genotypes for an additional >2 million autosomal SNPs. We carried out association analysis with these SNPs to identify genetic variants that predispose to T2D, compared our T2D association results with the results of two similar studies, and genotyped 80 SNPs in an additional 1215 Finnish T2D cases and 1258 Finnish NGT controls. We identify T2D-associated variants in an intergenic region of chromosome 11p12, contribute to the identification of T2D-associated variants near the genes IGF2BP2 and CDKAL1 and the region of CDKN2A and CDKN2B, and confirm that variants near TCF7L2, SLC30A8, HHEX, FTO, PPARG, and KCNJ11 are associated with T2D risk. This brings the number of T2D loci now confidently identified to at least 10.; New strategies for prevention and treatment of type 2 diabetes (T2D) require improved insight into disease etiology. We analyzed 386,731 common single-nucleotide polymorphisms (SNPs) in 1464 patients with T2D and 1467 matched controls, each characterized for measures of glucose metabolism, lipids, obesity, and blood pressure. With collaborators (FUSION and WTCCC/UKT2D), we identified and confirmed three loci associated with T2D-in a noncoding region near CDKN2A and CDKN2B, in an intron of IGF2BP2, and an intron of CDKAL1-and replicated associations near HHEX and in SLC30A8 found by a recent whole-genome association study. We identified and confirmed association of a SNP in an intron of glucokinase regulatory protein (GCKR) with serum triglycerides. The discovery of associated variants in unsuspected genes and outside coding regions illustrates the ability of genome-wide association studies to provide potentially important clues to the pathogenesis of common diseases.; Type 2 diabetes mellitus results from the interaction of environmental factors with a combination of genetic variants, most of which were hitherto unknown. A systematic search for these variants was recently made possible by the development of high-density arrays that permit the genotyping of hundreds of thousands of polymorphisms. We tested 392,935 single-nucleotide polymorphisms in a French case-control cohort. Markers with the most significant difference in genotype frequencies between cases of type 2 diabetes and controls were fast-tracked for testing in a second cohort. This identified four loci containing variants that confer type 2 diabetes risk, in addition to confirming the known association with the TCF7L2 gene. These loci include a non-synonymous polymorphism in the zinc transporter SLC30A8, which is expressed exclusively in insulin-producing beta-cells, and two linkage disequilibrium blocks that contain genes potentially involved in beta-cell development or function (IDE-KIF11-HHEX and EXT2-ALX4). These associations explain a substantial portion of disease risk and constitute proof of principle for the genome-wide approach to the elucidation of complex genetic traits.; Dominant mutations in ABCC8 accounted for 12 percent of cases of neonatal diabetes in the study group. Diabetes results from a newly discovered mechanism whereby the basal magnesium-nucleotide-dependent stimulatory action of SUR1 on the Kir pore is elevated and blockade by sulfonylureas is preserved.; Elevated blood concentrations of IL-6 have been shown to predict type 2 diabetes. Because the impact of IL-6 gene polymorphisms on diabetes status, parameters of the metabolic syndrome, and low-grade systemic inflammation has not been analyzed in a population-based study, we investigated the association of the IL-6 single nucleotide polymorphisms C-174G and A-598G on these parameters in 704 elderly participants of the Kooperative Gesundheitsforschung im Raum Augsburg/Cooperative Research in the Region of Augsburg (KORA) Survey 2000. Both -174G and -598G alleles were significantly associated with type 2 diabetes (-174G: odds ratio = 1.51, 95% confidence interval = 1.11-2.07, P = 0.0096; -598G: odds ratio = 1.56, 95% confidence interval = 1.13-2.15, P = 0.0069) but not with impaired glucose tolerance. In subgroup analyses, the association reached statistical significance in men and in leaner subjects (body mass index <or= 28.7 kg/m(2), i.e. study median) but not in women or more obese persons. Circulating IL-6 levels were not associated with the IL-6 polymorphisms, but significantly elevated levels of the chemokine monocyte chemoattractant protein-1/CC chemokine ligand 2 in carriers of the protective genotypes indicated an indirect effect of these single nucleotide polymorphisms on the innate immune system. Our findings confirm that immune gene polymorphisms can be considered as independent risk factors in the etiology of type 2 diabetes and suggest that their contribution may be indirect, by influencing the levels of other immune mediators like monocyte chemoattractant protein-1.; The prevalence of type 2 diabetes mellitus in the Oji-Cree of northwestern Ontario is the third highest in the world. A private mutation, G319S, in HNF1A, which encodes hepatic nuclear factor-1alpha (HNF-1alpha), was associated with Oji-Cree type 2 diabetes and was found in approximately 40% of affected subjects. The G319S mutation reduced the in vitro ability of HNF-1alpha to activate transcription by approximately 50%, with no effect on DNA binding or protein stability. There was no evidence of a dominant negative effect of the mutant protein. The impact of the G319S mutation at the population level was assessed by classifying subjects with type 2 diabetes according to HNF1A genotype and plotting the cumulative age of onset of diabetes. Disease onset was modeled satisfactorily by two-parameter sigmoidal functions for all diabetic subjects and all three HNF1A genotypes. Pairwise statistical comparisons showed significant between-genotype differences in t50 (all P < 0.00001), corresponding to the age at which half the subjects had become diabetic. Each dose of G319S accelerated median disease onset by approximately 7 years. Thus, the transactivation-deficient HNF1A G319S mutation affects the dynamics of disease onset. The demonstration of a functional consequence for HNF1A G319S provides a mechanistic basis for its strong association with Oji-Cree type 2 diabetes and its unparalleled specificity for diabetes prediction in these people, in whom diabetes presents a significant public health dilemma. The findings also show that HNF1A mutations can be associated with typical adult-onset insulin-resistant obesity-related diabetes in addition to maturity-onset diabetes of the young.; Pax4 is one of the transcription factors that play an important role in the differentiation of islet beta-cells. We scanned the Pax4 gene in 200 unrelated Japanese type 2 diabetic patients and found a missense mutation (R121W) in 6 heterozygous patients and 1 homozygous patient (mutant allele frequency 2.0%). The mutation was not found in 161 nondiabetic subjects. The R121W mutation was located in the paired domain and was thought to affect its transcription activity through lack of DNA binding. Six of seven patients had family history of diabetes or impaired glucose tolerance, and four of seven had transient insulin therapy at the onset. One of them, a homozygous carrier, had relatively early onset diabetes and slowly fell into an insulin-dependent state without an autoimmune-mediated process. This is the first report of a Pax4 gene mutation that exhibits loss of function and seems to be associated with type 2 diabetes. This work provides significant implications for the Pax4 gene as one of the predisposing genes for type 2 diabetes in the Japanese.; The transcription factor insulin promoter factor-1 (IPF-1) plays a central role in both the development of the pancreas and the regulation of insulin gene expression in the mature pancreatic beta cell. A dominant-negative frameshift mutation in the IPF-l gene was identified in a single family and shown to cause pancreatic agenesis when homozygous and maturity-onset diabetes of the young (MODY) when heterozygous. We studied the role of IPF-1 in Caucasian diabetic and nondiabetic subjects from the United Kingdom. Three novel IPF-1 missense mutations (C18R, D76N, and R197H) were identified in patients with type 2 diabetes. Functional analyses of these mutations demonstrated decreased binding activity to the human insulin gene promoter and reduced activation of the insulin gene in response to hyperglycemia in the human beta-cell line Nes2y. These mutations are present in 1% of the population and predisposed the subject to type 2 diabetes with a relative risk of 3.0. They were not highly penetrant MODY mutations, as there were nondiabetic mutation carriers 25-53 years of age. We conclude that mutations in the IPF-1 gene may predispose to type 2 diabetes and are a rare cause of MODY and pancreatic agenesis, with the phenotype depending upon the severity of the mutation.; In obesity and type 2 diabetes, expression of the GLUT4 glucose transporter is decreased selectively in adipocytes. Adipose-specific Glut4 (also known as Slc2a4) knockout (adipose-Glut4(-/-)) mice show insulin resistance secondarily in muscle and liver. Here we show, using DNA arrays, that expression of retinol binding protein-4 (RBP4) is elevated in adipose tissue of adipose-Glut4(-/-) mice. We show that serum RBP4 levels are elevated in insulin-resistant mice and humans with obesity and type 2 diabetes. RBP4 levels are normalized by rosiglitazone, an insulin-sensitizing drug. Transgenic overexpression of human RBP4 or injection of recombinant RBP4 in normal mice causes insulin resistance. Conversely, genetic deletion of Rbp4 enhances insulin sensitivity. Fenretinide, a synthetic retinoid that increases urinary excretion of RBP4, normalizes serum RBP4 levels and improves insulin resistance and glucose intolerance in mice with obesity induced by a high-fat diet. Increasing serum RBP4 induces hepatic expression of the gluconeogenic enzyme phosphoenolpyruvate carboxykinase (PEPCK) and impairs insulin signalling in muscle. Thus, RBP4 is an adipocyte-derived 'signal' that may contribute to the pathogenesis of type 2 diabetes. Lowering RBP4 could be a new strategy for treating type 2 diabetes.; Inherited defects in signaling pathways downstream of the insulin receptor have long been suggested to contribute to human type 2 diabetes mellitus. Here we describe a mutation in the gene encoding the protein kinase AKT2/PKBbeta in a family that shows autosomal dominant inheritance of severe insulin resistance and diabetes mellitus. Expression of the mutant kinase in cultured cells disrupted insulin signaling to metabolic end points and inhibited the function of coexpressed, wild-type AKT. These findings demonstrate the central importance of AKT signaling to insulin sensitivity in humans.; Impaired insulin action is a key feature of type 2 diabetes and is also found, to a more extreme degree, in familial syndromes of insulin resistance. Although inherited susceptibility to insulin resistance may involve the interplay of several genetic loci, no clear examples of interactions among genes have yet been reported. Here we describe a family in which five individuals with severe insulin resistance, but no unaffected family members, were doubly [corrected] heterozygous with respect to frameshift/premature stop mutations in two unlinked genes, PPARG and PPP1R3A these encode peroxisome proliferator activated receptor gamma, which is highly expressed in adipocytes, and protein phosphatase 1, regulatory subunit 3, the muscle-specific regulatory subunit of protein phosphatase 1, which are centrally involved in the regulation of carbohydrate and lipid metabolism, respectively. That mutant molecules primarily involved in either carbohydrate or lipid metabolism can combine to produce a phenotype of extreme insulin resistance provides a model of interactions among genes that may underlie common human metabolic disorders such as type 2 diabetes.; Protein tyrosine phosphatase 1B (PTP1B) inhibits insulin signaling and, when overexpressed, plays a role in insulin resistance (Ahmad et al. 1997). We identified, in the 3' untranslated region of the PTP1B gene, a 1484insG variation that, in two different populations, is associated with several features of insulin resistance: among male individuals, higher values of the insulin resistance HOMA(IR) index (P=.006), serum triglycerides (P=.0002), and total/HDL cholesterol ratio (P=.025) and, among female individuals, higher blood pressure (P=.01). Similar data were also obtained in a family-based association study by use of sib pairs discordant for genotype (Gu et al. 2000). Subjects carrying the 1484insG variant showed also PTP1B mRNA overexpression in skeletal muscle (6,166 plus minus 1,879 copies/40 ng RNA vs. 2,983 plus minus 1,620; P<.01). Finally, PTP1B mRNA stability was significantly higher (P<.01) in human embryo kidney 293 cells transfected with 1484insG PTP1B, as compared with those transfected with wild-type PTP1B. Our data indicate that the 1484insG allele causes PTP1B overexpression and plays a role in insulin resistance. Therefore, individuals carrying the 1484insG variant might particularly benefit from PTP1B inhibitors, a promising new tool for treatment of insulin resistance (Kennedy and Ramachandran 2000).; Mutations of the hepatic nuclear factor-1alpha (HNF-1alpha) gene have been found in patients with maturity-onset diabetes of the young. We examined the relation between the I27L polymorphism of HNF-1alpha and insulin sensitivity and beta-cell function assessed by a hyperglycemic clamp. This study included 52 healthy glucose-tolerant and normotensive subjects (age, 19-40 yr; body mass index, 17.58-35.61 kg/m2; waist/hip ratio, 0.65-1.03). We identified 19 LL subjects, 24 IL, and 9 II subjects. No difference was noted in the demographic features among the three genotypes. The LL group had the highest postchallenge insulin levels at 30 and 90 min (P = 0.038 and P = 0.015, respectively) and also the highest insulin area under curve (P = 0.009) among the three genotypes. The LL group was more insulin resistant than the IL and II groups (P = 0.042 for insulin sensitivity index). After adjusting for age, gender, obesity, and ethnicity, the I27L polymorphism was an independent determinant of the insulin sensitivity index (P = 0.001). However, it had no impact on either the first or second phase insulin response. Therefore, we conclude that the I27L polymorphism is associated with insulin resistance, but not beta-cell function. The mechanism of this association is unclear, but HNF-1alpha may play a role in regulating hepatic glucose metabolism.; Recently, it was reported that 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors increased bone mineral density (BMD) in mice. We studied the effect of HMG-CoA reductase inhibitors on BMD of type 2 diabetes mellitus by a retrospective review of medical records. Sixty-nine type 2 diabetic patients were included. The control group (n = 33) did not take HMG-CoA reductase inhibitors. The treatment group (n = 36) was administered either lovastatin, pravastatin, or simvastatin. BMD of the spine, femoral neck, femoral trochanter, and total hip were measured by dual-energy X-ray absorptiometry. There were no significant differences between control and treatment groups in age, sex, body mass index, glycemic control, and serum insulin levels. In the control group, BMD of the spine significantly decreased (from 1.116 +/- 0.165 to 1.081 +/- 0.178 g/cm2) after 14 months. In the treatment group, BMD of the femoral neck significantly increased (from 0.853 +/- 0.139 to 0.878 +/- 0.147 g/cm2) after 15 months. In male subjects treated with HMG-CoA reductase inhibitors, there was a significant increase in BMD of the femoral neck and femoral trochanter (from 0.899 +/- 0.139 to 0.934 +/- 0.139 and from 0.801 +/- 0.145 to 0.833 +/- 0.167 g/cm2, respectively), but in female subjects, only BMD of the femoral neck increased (from 0.819 +/- 0.132 to 0.834 +/- 0.143 g/cm2). Percentage increments of BMD of the femoral neck, femoral wards triangle, femoral trochanter, and total hip in the treatment group were significantly higher than in the control group (2.32% vs. -0.99, 1.77% vs. -1.25%, 1.40% vs. -1.21%, 0.88% vs. -1.03%, respectively). The proportion of subjects who had an increase in BMD of the spine and total hip more than two percentages was significantly larger in the treatment group than in the control group (30.6% vs. 15.2% and 30.6% vs. 9.1%, respectively). The increased increment in BMD of the treatment group was significantly greater than those in the control group after adjustment for age and body mass index (P < 0.05). These results suggest that HMG-CoA reductase inhibitors may increase BMD of the femur in male patients with type 2 diabetes mellitus.; Type 2 diabetes mellitus is a common disabling disease with onset in middle-aged individuals, caused by an imbalance between insulin production and action. Genetic studies point to major genetic components, but, with the exception of maturity-onset diabetes of the young (MODY), specific diabetes susceptibility genes remain to be identified. Recent studies showed that a dominant negative mutation in the insulin promoter factor-1 (IPF-1), a pancreatic beta-cell specific transcription factor, causes pancreatic agenesis and MODY. Thus, we investigated 192 French, non-MODY type 2 diabetic families for mutations in IPF-1. We identified 3 novel IPF-1 mutations, including 2 substitutions (Q59L and D76N) and an in-frame proline insertion (InsCCG243). Functional transactivation assays of these IPF-1 mutant isoforms in a beta-pancreatic tumor cell line transfected with a transcriptional reporter and IPF-1 expression plasmids demonstrate a significant inhibition of basal insulin promoter activity (stronger with the InsCCG243 mutant). We find that the InsCCG243 mutation is linked, in 2 families, to an autosomal dominant-like late-onset form of type 2 diabetes, in which insulin secretion becomes progressively impaired. The lower penetrance D76N and Q59L mutations were more prevalent and were associated with a relative risk of 12.6 for diabetes and with decreased glucose-stimulated insulin-secretion in nondiabetic subjects. We propose that IPF-1 mutations can cause MODY or apparently monogenic late-onset diabetes and that they represent a significant risk factor for type 2 diabetes in humans.; The helix-loop-helix (HLH) protein NEUROD1 (also known as BETA2) functions as a regulatory switch for endocrine pancreatic development. In mice homozygous for a targeted disruption of Neurod, pancreatic islet morphogenesis is abnormal and overt diabetes develops due in part to inadequate expression of the insulin gene (Ins2). NEUROD1, following its heterodimerization with the ubiquitous HLH protein E47, regulates insulin gene (INS) expression by binding to a critical E-box motif on the INS promoter. Here we describe two mutations in NEUROD1, which are associated with the development of type 2 diabetes in the heterozygous state. The first, a missense mutation at Arg 111 in the DNA-binding domain, abolishes E-box binding activity of NEUROD1. The second mutation gives rise to a truncated polypeptide lacking the carboxy-terminal trans-activation domain, a region that associates with the co-activators CBP and p300 (refs 3,4). The clinical profile of patients with the truncated NEUROD1 polypeptide is more severe than that of patients with the Arg 111 mutation. Our findings suggest that deficient binding of NEUROD1 or binding of a transcriptionally inactive NEUROD1 polypeptide to target promoters in pancreatic islets leads to the development of type 2 diabetes in humans.; The genes responsible for insulin resistance are poorly defined. Plasma cell differentiation antigen (PC-1) glycoprotein inhibits insulin receptor signaling and is associated with insulin resistance. We describe here a novel polymorphism in exon 4 of the PC-1 gene (K121Q) and demonstrate that it is strongly associated with insulin resistance in 121 healthy nonobese (BMI <30 kg/m2) nondiabetic (by oral glucose tolerance test [OGTT]) Caucasians from Sicily. Compared with 80 KK subjects, Q allele carriers (n = 41, 39 KQ and 2 QQ) showed higher glucose and insulin levels during OGTT (P < 0.001 by two-way analysis of variance) and insulin resistance by euglycemic clamp (M value = 5.25 +/- 1.38 [n = 24] vs. 6.30 +/- 1.39 mg x kg(-1) x min(-1) [n = 49], P = 0.005). Q carriers had higher risk of being hyperinsulinemic and insulin resistant (odds ratio [CI]: 2.99 [1.28-7.0], P < 0.001). Insulin receptor autophosphorylation was reduced (P < 0.01) in cultured skin fibroblasts from KQ versus KK subjects. Skeletal muscle PC-1 content was not different in 11 KQ versus 32 KK subjects (33 +/- 16.1 vs. 17.5 +/- 15 ng/mg protein, P = 0.3). These results suggest a cause-effect relationship between the Q carrying genotype and the insulin resistance phenotype, and raise the possibility that PC-1 genotyping could identify individuals who are at risk of developing insulin resistance, a condition that predisposes to type 2 diabetes and coronary artery disease.; Insulin resistance is frequently associated with acanthosis nigricans and hyperandrogenism. In patients with type A insulin resistance, this has been shown to be due to genetic defects in insulin receptor function. However, other patients with a similar clinical syndrome have been reported to have a variant of this syndrome, in which assays of insulin receptor function were normal. We have sequenced a portion of the insulin receptor gene in one such patient, a 29-yr-old woman with obesity and insulin resistance. The patient is heterozygous for a mutation substituting isoleucine for methionine at position 1153. Met1153 is located in the intracellular domain of the receptor near the cluster of tyrosine phosphorylation sites at positions 1158, 1162, and 1163. Studies of the mutant receptor expressed in NIH-3T3 cells demonstrated that the Ile1153-mutation impairs the ability of insulin to stimulate autophosphorylation of solubilized insulin receptors. In addition, the mutation impairs the ability of insulin to stimulate receptor tyrosine kinase activity to phosphorylate an artificial substrate [poly(Glu-Tyr)]. It seems likely that this defect in receptor tyrosine kinase activity explains the defect in the ability of the patient's insulin receptors to mediate insulin action in vivo. Furthermore, this patient provides a paradigm in which genetic factors act in concert with other risk factors, such as obesity, to cause clinically important insulin resistance.; Type 2 diabetes mellitus (T2DM) is a multifactorial polygenic disease. Potassium inwardly-rectifying channel, subfamily J, member 11 (<i>KCNJ11)</i> gene mutations can result in susceptibility of T2DM. The aim of this study is to investigate the relationship between risk of T2DM and its complications (retinopathy & renal) and polymorphisms rs5210 and rs5215 of the <i>KCNJ11</i> gene in a group of Iranian population. In this case-control study, 111 Iranian patients with T2DM and 82 control subjects were genotyped for each polymorphism by polymerase chain reaction (PCR) and Sanger Sequencing methods. Frequencies of genotypes of rs5210 polymorphism among subjects with and without diabetes mellitus were 53.15% vs. 51.22% for GG and 37.84% vs. 42.68% for AG (<i>p</i> = 0.7), respectively. Corresponding frequencies for rs5215 polymorphism among diabetics and non-diabetics were 13.51% vs. 13.41% for CC and 50.45% vs. 37.80% for CT (<i>p</i> = 0.2). G allele carriers (rs5210 polymorphism) and C allele carriers (rs5215 polymorphism) had the same frequency among diabetics and non-diabetics (<i>p</i> = 0.9 for G allele and <i>p</i> = 0.2 for C allele). Our results suggested that none of the polymorphisms of <i>KCNJ11</i>, rs5210 (<i>p</i> = 0.7) and rs5215 (<i>p</i> = 0.2), were significantly associated with T2DM. Only, the relationship between CT genotype of rs5215 and retinopathy (<i>p</i> = 0.01) showed a borderline significant association.; Compared with healthy controls, the presence of functional HMGA1 gene variants in individuals of white European ancestry was associated with type 2 DM.; Recent advances in genome research have enabled the identification of new genomic variations that are associated with type 2 diabetes mellitus (T2DM). Via fine mapping of SNPs in a candidate region of chromosome 21q, the current study identifies potassium inwardly-rectifying channel, subfamily J, member 15 (KCNJ15) as a new T2DM susceptibility gene. KCNJ15 is expressed in the beta cell of the pancreas, and a synonymous SNP, rs3746876, in exon 4 (C566T) of this gene, with T allele frequency among control subjects of 3.1%, showed a significant association with T2DM affecting lean individuals in three independent Japanese sample sets (p = 2.5 x 10(-7), odds ratio [OR] = 2.54, 95% confidence interval [CI] = 1.76-3.67) and with unstratified T2DM (p = 6.7 x 10(-6), OR = 1.76, 95% CI = 1.37-2.25). The diabetes risk allele frequency was, however, very low among Europeans in whom no association between this variant and T2DM could be shown. Functional analysis in human embryonic kidney 293 cells demonstrated that the risk allele of the synonymous SNP in exon 4 increased KCNJ15 expression via increased mRNA stability, which resulted in the higher expression of protein as compared to that of the nonrisk allele. We also showed that KCNJ15 is expressed in human pancreatic beta cells. In conclusion, we demonstrated a significant association between a synonymous variant in KCNJ15 and T2DM in lean Japanese patients with T2DM, suggesting that KCNJ15 is a previously unreported susceptibility gene for T2DM among Asians.; Metabolic dyslipidemia is characterized by high circulating triglyceride (TG) and low HDL cholesterol levels and is frequently accompanied by hepatic steatosis. Increased hepatic lipogenesis contributes to both of these problems. Because insulin fails to suppress gluconeogenesis but continues to stimulate lipogenesis in both obese and lipodystrophic insulin-resistant mice, it has been proposed that a selective postreceptor defect in hepatic insulin action is central to the pathogenesis of fatty liver and hypertriglyceridemia in these mice. Here we show that humans with generalized insulin resistance caused by either mutations in the insulin receptor gene or inhibitory antibodies specific for the insulin receptor uniformly exhibited low serum TG and normal HDL cholesterol levels. This was due at least in part to surprisingly low rates of de novo lipogenesis and was associated with low liver fat content and the production of TG-depleted VLDL cholesterol particles. In contrast, humans with a selective postreceptor defect in AKT2 manifest increased lipogenesis, elevated liver fat content, TG-enriched VLDL, hypertriglyceridemia, and low HDL cholesterol levels. People with lipodystrophy, a disorder characterized by particularly severe insulin resistance and dyslipidemia, demonstrated similar abnormalities. Collectively these data from humans with molecularly characterized forms of insulin resistance suggest that partial postreceptor hepatic insulin resistance is a key element in the development of metabolic dyslipidemia and hepatic steatosis.; We carried out a multistage genome-wide association study of type 2 diabetes mellitus in Japanese individuals, with a total of 1,612 cases and 1,424 controls and 100,000 SNPs. The most significant association was obtained with SNPs in KCNQ1, and dense mapping within the gene revealed that rs2237892 in intron 15 showed the lowest Pvalue (6.7 x 10(-13), odds ratio (OR) = 1.49). The association of KCNQ1 with type 2 diabetes was replicated in populations of Korean, Chinese and European ancestry as well as in two independent Japanese populations, and meta-analysis with a total of 19,930 individuals (9,569 cases and 10,361 controls) yielded a P value of 1.7 x 10(-42) (OR = 1.40; 95% CI = 1.34-1.47) for rs2237892. Among control subjects, the risk allele of this polymorphism was associated with impairment of insulin secretion according to the homeostasis model assessment of beta-cell function or the corrected insulin response. Our data thus implicate KCNQ1 as a diabetes susceptibility gene in groups of different ancestries.; Transcription factor 7-like 2 (TCF7L2) has been shown to be associated with type 2 diabetes mellitus in multiple ethnic groups. Regarding the Asian population, Horikoshi et al. (Diabetologia 50:747-751, 2007) and Hayashi et al. (Diabetologia 50:980-984, 2007) reported that single nucleotide polymorphisms (SNPs) in TCF7L2 were associated with type 2 diabetes in the Japanese population, while contradictory results were reported for Han Chinese populations. The aim of this study was to investigate the associations of the TCF7L2 gene with type 2 diabetes using a relatively large sample size: 2,214 Japanese individuals with type 2 diabetes and 1,873 normal controls. The minor alleles of rs7903146, rs11196205, and rs12255372 showed significant associations with type 2 diabetes (OR=1.48, P=2.7 x 10(-4); OR=1.39, P=4.6 x 10(-4); OR=1.70, P=9.8 x 10(-5), respectively) in the combined sample sets. However, neither rs11196218 nor rs290487 showed a significant association. These results indicate that TCF7L2 is an important susceptibility gene for type 2 diabetes in the Japanese population.; Independent of subclinical inflammation and vitamin A intakes, serum RBP4 and the RBP4-to-SR ratio are correlated with obesity, central obesity, and components of the metabolic syndrome in prepubertal and early pubertal children.; Insulin resistance is often associated with obesity and can precipitate type 2 diabetes. To date, most known approaches that improve insulin resistance must be preceded by the amelioration of obesity and hepatosteatosis. Here, we show that this provision is not mandatory; insulin resistance and hyperglycemia are improved by the modification of hepatic fatty acid composition, even in the presence of persistent obesity and hepatosteatosis. Mice deficient for Elovl6, the gene encoding the elongase that catalyzes the conversion of palmitate to stearate, were generated and shown to become obese and develop hepatosteatosis when fed a high-fat diet or mated to leptin-deficient ob/ob mice. However, they showed marked protection from hyperinsulinemia, hyperglycemia and hyperleptinemia. Amelioration of insulin resistance was associated with restoration of hepatic insulin receptor substrate-2 and suppression of hepatic protein kinase C epsilon activity resulting in restoration of Akt phosphorylation. Collectively, these data show that hepatic fatty acid composition is a new determinant for insulin sensitivity that acts independently of cellular energy balance and stress. Inhibition of this elongase could be a new therapeutic approach for ameliorating insulin resistance, diabetes and cardiovascular risks, even in the presence of a continuing state of obesity.; We performed a genome-wide association scan to search for sequence variants conferring risk of prostate cancer using 1,501 Icelandic men with prostate cancer and 11,290 controls. Follow-up studies involving three additional case-control groups replicated an association of two variants on chromosome 17 with the disease. These two variants, 33 Mb apart, fall within a region previously implicated by family-based linkage studies on prostate cancer. The risks conferred by these variants are moderate individually (allele odds ratio of about 1.20), but because they are common, their joint population attributable risk is substantial. One of the variants is in TCF2 (HNF1beta), a gene known to be mutated in individuals with maturity-onset diabetes of the young type 5. Results from eight case-control groups, including one West African and one Chinese, demonstrate that this variant confers protection against type 2 diabetes.; RBP4 is an adipocyte-secreted molecule that is elevated in the serum before the development of frank diabetes and appears to identify insulin resistance and associated cardiovascular risk factors in subjects with varied clinical presentations. These findings provide a rationale for antidiabetic therapies aimed at lowering serum RBP4 levels.; Ecto-nucleotide pyrophosphatase/phosphodiesterase 1 (ENPP1, also known as PC-1) inhibits insulin signal transduction pathway(s). Previous studies have demonstrated the K121Q variant of the ENPP1 gene to have a significant functional role in determining susceptibility to insulin resistance and type 2 diabetes (T2D). To assess whether the K121Q variant has any impact on T2D in Japanese, we undertook an extensive case-control association study using a total of 911 unrelated Japanese T2D patients and 876 control subjects. No significant difference was observed in either genotype distribution (P=0.95) or allele frequency (P=0.83) between T2D and control groups. Notably, the frequency of the ancestral Q121 allele, which is also present in other primates, was quite high in African-Americans, and showed a marked ethnic variation (77.3% in African-Americans, 16.7% in European Americans, 10.5% in Japanese and 4.2% in Han Chinese). Consequently, the pairwise F(ST )value (a classic measure of genetic distance between pairs of population) showed highly significant differentiations between African-American and non-African-American populations (F(ST)>0.3). Our results indicated that the K121Q variant of the ENPP1 gene has very little, if any, impact on T2D susceptibility in Japanese, but may play a role in the inter-ethnic variability in insulin resistance and T2D.; We identified a locus on chromosome 6q16.3-q24.2 (ref. 1) associated with childhood obesity that includes 2.4 Mb common to eight genome scans for type 2 diabetes (T2D) or obesity. Analysis of the gene ENPP1 (also called PC-1), a candidate for insulin resistance, in 6,147 subjects showed association between a three-allele risk haplotype (K121Q, IVS20delT-11 and A-->G+1044TGA; QdelTG) and childhood obesity (odds ratio (OR) = 1.69, P = 0.0006), morbid or moderate obesity in adults (OR = 1.50, P = 0.006 or OR = 1.37, P = 0.02, respectively) and T2D (OR = 1.56, P = 0.00002). The Genotype IBD Sharing Test suggested that this obesity-associated ENPP1 risk haplotype contributes to the observed chromosome 6q linkage with childhood obesity. The haplotype confers a higher risk of glucose intolerance and T2D to obese children and their parents and associates with increased serum levels of soluble ENPP1 protein in children. Expression of a long ENPP1 mRNA isoform, which includes the obesity-associated A-->G+1044TGA SNP, was specific for pancreatic islet beta cells, adipocytes and liver. These findings suggest that several variants of ENPP1 have a primary role in mediating insulin resistance and in the development of both obesity and T2D, suggesting that an underlying molecular mechanism is common to both conditions.; To search a gene(s) conferring susceptibility to type 2 diabetes mellitus, we genotyped nearly 60,000 gene-based SNPs for Japanese patients and found evidence that the gene at chromosome 6p12 encoding transcription-factor-activating protein 2beta (TFAP2B) was a likely candidate in view of significant association of polymorphism in this gene with type 2 diabetes. Extensive analysis of this region identified that several variations within TFAP2B were significantly associated with type 2 diabetes [a variable number of tandem repeat locus: chi(2)=10.9, P=0.0009; odds ratio=1.57, 95% CI 1.20-2.06, intron 1+774 (G/T); chi(2)=11.6, P=0.0006; odds ratio=1.60, 95% CI 1.22-2.09, intron 1+2093 (A/C); chi(2)=12.2, P=0.0004; odds ratio=1.61, 95% CI 1.23-2.11]. The association of TFAP2B with type 2 diabetes was also observed in the UK population. These results suggest that TFAP2B might be a new candidate for conferring susceptibility to type 2 diabetes and contribute to the pathogenesis of type 2 diabetes.; In population-based studies, dyslipidemia related to insulin resistance (high triglyceride level and low high-density lipoprotein cholesterol level) is a risk factor for type 2 diabetes. Therefore, variants in genes regulating lipid and lipoprotein metabolism are potential candidate genes for diabetes. We investigated whether the G-250A polymorphism of the hepatic lipase gene (LIPC) predicts the conversion from impaired glucose tolerance (IGT) to type 2 diabetes in the Finnish Diabetes Prevention Study. This study randomized subjects to either the intervention group (lifestyle modification aimed at weight loss, such as changes in diet and increased physical exercise) or the control group. Genotyping at position -250 of the LIPC gene was performed with PCR amplification, DraI enzyme digestion, and gel electrophoresis in 490 subjects with IGT whose DNA was available. In the entire study population, the conversion rate to type 2 diabetes was 17.8% among subjects with the G-250G genotype and 10.7% among subjects with the -250A allele (P = 0.032). In univariate analysis, the odds ratio for the G-250G genotype to predict the conversion from IGT to type 2 diabetes was 1.80 (95% confidence interval, 1.05-3.10; P = 0.034). In multivariate logistic regression analysis, the G-250G genotype predicted the conversion to diabetes independently of the study group (control or intervention), gender, weight, waist circumference at baseline, and change in weight and waist circumference. In the intervention group, 13.0% of subjects with the G-250G genotype and 1.0% of the subjects with the -250A allele converted to diabetes (P = 0.001). We conclude that the G-250G genotype of the LIPC gene is a risk factor for type 2 diabetes. Therefore, genes regulating lipid and lipoprotein metabolism may be potential candidate genes for type 2 diabetes.; Birth weight and length serve as indicators of the intrauterine environment, and a small body size at birth is a predictor of type 2 diabetes and hypertension. Insulin is one of the growth factors regulating fetal growth. The plasma cell glycoprotein 1 (PC-1) gene impairs insulin signaling at the insulin receptor level. Therefore, we investigated whether the K121Q polymorphism of the PC-1 gene association with insulin sensitivity, insulin levels, and the prevalence of diabetes and hypertension in adult life depends on size at birth in 489 subjects born in Helsinki during 1924-1933. We found that the effect of the PC-1 gene polymorphism on insulin levels and insulin sensitivity, measured as the homeostasis model assessment for insulin resistance, depended on birth length because fasting insulin levels and insulin resistance were highest in subjects carrying the 121Q allele who were small at birth (P for interaction = 0.04 and 0.05). Additionally, in those whose birth length was up to 49 cm, the K121Q polymorphism of the PC-1 gene was associated with a 2-fold higher incidence of type 2 diabetes. Moreover, subjects who were short at birth and who had the 121Q allele had the highest incidence (31.6%) of type 2 diabetes together with hypertension. We conclude that the interaction between the K121Q polymorphism of the PC-1 gene and birth length affects insulin sensitivity and increases susceptibility to type 2 diabetes and hypertension in adulthood.; Genetic susceptibility may be responsible for high prevalence of insulin resistance in Asian Indians. This study was carried out in samples of local Asian Indians and Caucasians to determine whether plasma cell membrane glycoprotein (PC)-1 K121Q and insulin receptor substrate-1 (IRS-1) G972A polymorphisms contribute significantly to susceptibility to insulin resistance in Asian Indians. The frequency of carrying at least one copy of the PC-1 121Q variant in Asian Indians was significantly higher than that in Caucasians (P = 0.01), but the frequency was similar for IRS-1 972A (6% and 7%). A significantly higher insulin area under the curve during oral glucose tolerance testing (P < 0.0001) and lower insulin sensitivity during hyperinsulinemic-euglycemic clamps (P = 0.04) were found in Asian Indians with PC-1 121Q variant compared with Asian Indians with wild-type PC-1 and with Caucasians with or without the polymorphism. IRS-1 972A was not associated with any change in insulin sensitivity. We conclude that the PC-1 K121Q polymorphism associates with primary insulin resistance in migrant Asian Indians. A relatively high frequency of this polymorphism thus may be one factor contributing to insulin resistance susceptibility in Asian Indians. This finding indicates the need for expanded studies on the association between PC-1 K121Q and insulin resistance in a representative sample of the Asian Indian population.; Diabetes mellitus is a recognized consequence of hereditary haemochromatosis. Whether the common HFE mutations, that associate with this condition and pre-dispose to increases in serum iron indices, are over-represented in diabetic populations remains controversial. We present data from the largest case-control study of the C282Y and H63D HFE allele frequencies in typical type 2 diabetes mellitus, as defined by an age of onset greater than 30 years and no requirement for insulin in the first year post-diagnosis. We also present a meta-analysis of all similar studies to date. We see no evidence for over-representation of iron loading HFE alleles in type 2 diabetes mellitus, suggesting that screening for HFE mutations in this population is of no value.; A genome-wide scan was performed, using nonparametric linkage analyses, to find susceptibility loci for type 2 diabetes mellitus in the Dutch population. We studied 178 families from The Netherlands, who constituted 312 affected sibling pairs. The first stage of the genome scan consisted of 270 DNA markers, with an average intermarker spacing of 13 cM. Because obesity and type 2 diabetes mellitus are interrelated, the data set was stratified for the subphenotype body mass index, corrected for age and gender. This resulted in a suggestive maximum multipoint LOD score of 2.3 (single-point P value, 9.7 x 10(-4); genome-wide P value, 0.028) for the most obese 20% pedigrees of the data set, between marker loci D18S471 and D18S843. In the lowest 80% obese pedigrees, two interesting loci on chromosome 2 and 19 were found, with LOD scores of 1.5 and 1.3. We provide independent evidence that the chromosome 18p11 locus, reported earlier from a Finnish/Swedish population, is of definite interest for type 2 diabetes mellitus in connection with obesity. Subsequently, our results indicate that two novel loci may reside on chromosomes 2 and 19, with minor effects involved in the development of type 2 diabetes mellitus in the Dutch population.; Insulin resistance is a major factor in the pathogenesis of type 2 diabetes in the elderly. To investigate how insulin resistance arises, we studied healthy, lean, elderly and young participants matched for lean body mass and fat mass. Elderly study participants were markedly insulin-resistant as compared with young controls, and this resistance was attributable to reduced insulin-stimulated muscle glucose metabolism. These changes were associated with increased fat accumulation in muscle and liver tissue assessed by 1H nuclear magnetic resonance (NMR) spectroscopy, and with a approximately 40% reduction in mitochondrial oxidative and phosphorylation activity, as assessed by in vivo 13C/31P NMR spectroscopy. These data support the hypothesis that an age-associated decline in mitochondrial function contributes to insulin resistance in the elderly.; Naturally occurring mutations in insulin receptor substrate-1 (IRS-1) have previously been implicated in impaired insulin action. We now report a novel mutation in IRS-1 with substitution of Arg for Thr(608) that was identified in a patient with type 2 diabetes mellitus. We detected the T608R mutation in 1 of 136 chromosomes from diabetic patients and in 0 of 120 chromosomes from nondiabetic controls, suggesting that this is a rare IRS-1 variant. Conservation of Thr(608) in human, monkey, rat, mouse, and chicken IRS-1 sequences is consistent with a crucial function for this residue. Moreover, Thr(608) is located near the YMXM motif containing Tyr(612) that is important for binding and activation of phosphoinositol 3-kinase (PI 3-kinase). To investigate whether the T608R mutation impairs insulin signaling, we transiently transfected NIH-3T3(IR) cells with hemagglutinin-tagged wild-type or T608R mutant IRS-1 constructs. Recombinant IRS-1 immunoprecipitated from transfected cells treated with or without insulin was subjected to immunoblotting for the p85 regulatory subunit of PI 3-kinase as well as a PI 3-kinase assay. As expected, in control cells transfected with wild-type IRS-1, insulin stimulation caused an increase in p85 coimmunoprecipitated with IRS-1 as well as a 10-fold increase in IRS-1-associated PI 3-kinase activity. Interestingly, when cells transfected with IRS1-T608R were stimulated with insulin, both the amount of p85 coimmunoprecipitated with IRS1-T608R as well as the associated PI 3-kinase activity were approximately 50% less than those observed with wild-type IRS-1. Moreover, in rat adipose cells, overexpression of IRS1-T608R resulted in significantly less translocation of GLUT4 to the cell surface than comparable overexpression of wild-type IRS-1. We conclude that a naturally occurring substitution of Arg for Thr(608) in IRS-1 is a rare human mutation that may contribute to insulin resistance by impairing metabolic signaling through PI 3-kinase-dependent pathways.; PC-1 is a membrane glycoprotein that impairs insulin receptor function. Its K121Q polymorphism is a genetic determinant of insulin resistance. We investigated whether the PC-1 gene modulates insulin sensitivity independently of weight status (i.e. both in nonobese and obese individuals). Nondiabetic subjects [164 males, 267 females; age, 37 +/- 0.6 yr, mean +/- SEM; body mass index (BMI), 32.7 +/- 0.5 kg/m(2)], who were subdivided into 220 nonobese (BMI < or = 29.9) and 211 obese, were studied. Although subjects were nondiabetic by selection criteria, plasma insulin concentrations during oral glucose tolerance test were higher (P < 0.05) in Q allele-carrying subjects (K121Q or Q121Q genotypes), compared with K121K individuals, in both the nonobese and obese groups. Insulin sensitivity, measured by euglycemic clamp in a representative subgroup of 131 of 431 randomly selected subjects, progressively decreased (P < 0.001) from nonobese K121K [n = 61; glucose disposal (M) = 34.9 +/- 1.1 micromol/kg/min] to nonobese Q (n = 21; M = 29.9 +/- 2.0), obese K121K (n = 31, M = 18.5 +/- 1.2), and obese Q (n = 18, M = 15.5 +/- 1.2) carriers. The K121Q polymorphism was correlated with insulin sensitivity independently (P < 0.05) of BMI, gender, age, and waist circumference. In conclusion, the Q121 PC-1 variant and obesity have independent and additive effects in causing insulin resistance.; We show that high doses of salicylates reverse hyperglycemia, hyperinsulinemia, and dyslipidemia in obese rodents by sensitizing insulin signaling. Activation or overexpression of the IkappaB kinase beta (IKKbeta) attenuated insulin signaling in cultured cells, whereas IKKbeta inhibition reversed insulin resistance. Thus, IKKbeta, rather than the cyclooxygenases, appears to be the relevant molecular target. Heterozygous deletion (Ikkbeta+/-) protected against the development of insulin resistance during high-fat feeding and in obese Lep(ob/ob) mice. These findings implicate an inflammatory process in the pathogenesis of insulin resistance in obesity and type 2 diabetes mellitus and identify the IKKbeta pathway as a target for insulin sensitization.; Mutations in the gene encoding hepatic nuclear factor-1alpha (HNF-1alpha) have been found in patients with maturity-onset diabetes of the young. We identified a new variant in the HNF-1alpha gene, namely G319S, in Ontario Oji-Cree with type 2 diabetes. G319S is within the proline II-rich domain of the trans-activation site of HNF-1alpha and alters a glycine residue that is conserved throughout evolution. S319 was absent from 990 alleles taken from subjects representing six other ethnic groups, suggesting that it is private for Oji-Cree. We found that 1) the S319 allele was significantly more prevalent in diabetic than nondiabetic Oji-Cree (0.209 vs. 0.087; P = 0.000001); 2) S319/S319 homozygotes and S319/G319 heterozygotes, respectively, had odds ratios for type 2 diabetes of 4.00 (95% confidence interval, 2.65-6.03) and 1.97 (95% confidence interval, 1.44-2.70) compared with G319/G319 homozygotes; 3) there was a significant difference in the mean age of onset of type 2 diabetes, with G319/G319, S319/G319, and S319/S319 subjects affected in the fifth, fourth, and third decades of life, respectively. In subjects with type 2 diabetes, we also found significantly lower body mass index and significantly higher post-challenge plasma glucose in S319/S319 and S319/G319 compared with G319/G319 subjects. Finally, among nondiabetic subjects, S319/G319 heterozygotes had significantly lower plasma insulin than G319/G319 homozygotes. The presence of the private HNF-1alpha G319S variant in a large number of Oji-Cree with type 2 diabetes and its strong association with type 2 diabetes susceptibility are unique among human populations. Also, G319S is associated with a distinct form of type 2 diabetes, characterized by onset at an earlier age, lower body mass, and a higher postchallenge plasma glucose.; To assess the effects of troglitazone monotherapy on glycemic control in patients with type 2 diabetes mellitus, we carried out a 6-month, randomized, double-blind, placebo-controlled study in 24 hospital and outpatient clinics in the United States and Canada. Troglitazone 100, 200, 400, or 600 mg or placebo once daily with breakfast was administered to 402 patients with type 2 diabetes with fasting serum glucose (FSG) > 140 mg/dL, glycosylated hemoglobin (HbA1c) > 6.5%, and fasting C-peptide > or = 1.5 ng/mL. Prior oral hypoglycemic therapy was withdrawn in patients who received it before the study. FSG, HbA1c, C-peptide, and serum insulin were evaluated at baseline and the end of the study. Analysis was performed on two subsets of patients based on prestudy therapy: Patients treated with diet and exercise only before the study (22% of patients), and those who had been receiving sulfonylurea therapy (78% of patients). Patients treated with 400 and 600 mg troglitazone had significant decreases from baseline in mean FSG and HbA1c at month 6 compared with placebo-treated patients (FSG: -51 and -60 mg/dL, respectively; HbA1c: -0.7 and -1.1%, respectively). In the diet-only subset, 600 mg troglitazone therapy resulted in a significant (P < 0.05) reduction in HbA1c (-1.35%) and a significant reduction in FSG (-42 mg/dL) compared with placebo. Patients previously treated with sulfonylurea therapy had significant (P < 0.05) decreases in mean FSG with 200-600 mg troglitazone therapy compared with placebo (-48, -61, and -66 mg/dL, respectively). Significant (P < 0.05) decreases in mean HbA1c occurred with 400 and 600 mg troglitazone therapy at month 6 (-0.8 and -1.2%, respectively) compared with placebo in this same subset. Significant (P < 0.05) decreases in triglycerides and free fatty acids occurred with troglitazone 400 and 600 mg, and increased high-density lipoprotein occurred with 600 mg troglitazone. We conclude that troglitazone monotherapy significantly improves HbA1c and fasting serum glucose, while lowering insulin and C-peptide in patients with type 2 diabetes. Troglitazone 600 mg monotherapy is efficacious for patients who are newly diagnosed and have never received pharmacological intervention for diabetes.; Non-insulin-dependent diabetes mellitus (NIDDM) is a heterogeneous disorder characterized by hyperglycemia resulting from defects in insulin secretion and action. Recent studies have found mutations in the hepatocyte nuclear factor-4 alpha gene (HNF-4alpha) in families with maturity-onset diabetes of the young (MODY), an autosomal dominant form of diabetes characterized by early age at onset and a defect in glucose-stimulated insulin secretion. During the course of our search for susceptibility genes contributing to the more common late-onset NIDDM forms, we observed nominal evidence for linkage between NIDDM and markers in the region of the HNF-4alpha/MODY1 locus in a subset of French families with NIDDM diagnosed before 45 yr of age. Thus, we screened these families for mutations in the HNF-4alpha gene. We found a missense mutation, resulting in a valine-to-isoleucine substitution at codon 393 in a single family. This mutation cosegregated with diabetes and impaired insulin secretion, and was not present in 119 control subjects. Expression studies showed that this conservative substitution is associated with a marked reduction of transactivation activity, a result consistent with this mutation contributing to the insulin secretory defect observed in this family.; Mitochondrial DNA is maternally inherited. Mitochondrial DNA mutations could contribute to the excess of maternal over paternal inheritance of non-insulin-dependent diabetes mellitus (NIDDM). We therefore investigated the relationship between this variant, insulin resistance and other risk factors in a cohort which had been well characterised with respect to diabetes. Blood DNA was screened from 251 men born in Hertfordshire 1920-1930 in whom an earlier cohort study had shown that glucose tolerance was inversely related to birthweight. The 16189 variant (T--> C transition) in the first hypervariable region of mitochondrial DNA was detected using the polymerase chain reaction and restriction digestion. DNA analysis showed that 28 of the 251 men (11%) had the 16189 variant. The prevalence of the 16189 variant increased progressively with fasting insulin concentration (p < 0.01). The association was independent of age and body mass index and was present after exclusion of the patients with NIDDM or impaired glucose tolerance. We found that insulin resistance in adult life was associated with the 16189 variant. This study provides the first evidence that a frequent mitochondrial variant may contribute to the phenotype in patients with a common multifactorial disorder.; The regulatory G-subunit of the glycogen-associated form of protein phosphatase 1 (PP1) plays a crucial part in muscle tissue glycogen synthesis and breakdown. As impaired insulin stimulated glycogen synthesis in peripheral tissues is considered to be a pathogenic factor in subsets of non-insulin-dependent diabetes mellitus (NIDDM) and obesity, the G-subunit of PP1 should be viewed as a candidate gene for inherited insulin resistance. When applying heteroduplex formation analysis and nucleotide sequencing of PP1G-subunit cDNA from 30 insulin resistant white NIDDM patients two cases were identified as heterozygous carriers of an Asp905 --> Tyr substitution. The carrier prevalence of the PP1G-subunit variant was 18% in 150 healthy subjects and 13% in 313 NIDDM subjects (chi 2 = 1.94, p = 0.16). Twenty-seven healthy subjects volunteered for a 4 h euglycaemic, hyperinsulinaemic clamp in combination with indirect calorimetry in order to elucidate the potential impact of the Tyr905 substitution on the whole body glucose metabolism. Interestingly, the Tyr905 variant was associated with altered routing of glucose: a decreased insulin stimulated non-oxidative glucose metabolism of peripheral tissues (glycogen synthesis) (p < 0.04) and an increased basal glucose oxidation rate (p < 0.04) when compared with wild type carriers. A population-based sample of 380 unrelated young healthy Caucasians was examined during a combined intravenous glucose and tolbutamide test to address whether the Asp905/Tyr905 polymorphism was associated with alterations in insulin secretion which might be secondary to the insulin resistance of skeletal muscle.(ABSTRACT TRUNCATED AT 250 WORDS); Insulin receptor (IR) and insulin-responsive glucose transporter (Glut4) represent two candidate genes involved in the development of non-insulin dependent diabetes mellitus (NIDDM); detection of molecular alterations in these genes might explain their possible contribution to NIDDM. Recently, mutations within the coding region of IR and Glut4 have identified: they include the Glut4Ile383 and IRGln1152 variants which were found at low frequencies in diabetic Caucasian populations. In this study Italian NIDDM patients and control subjects were analysed and mutated alleles were not found. Therefore in our population these variants appear to have little relevance to the genetic susceptibility to NIDDM.; Glucokinase, the major enzyme that phosphorylates glucose upon entry into liver and islet beta-cells, has been considered a prime candidate for inherited defects predisposing to NIDDM. Now that the human gene has been isolated, this question has been addressed directly. Polymorphic markers flanking the gene were identified. These markers (microsatellites) are composed of variable numbers of dinucleotide repeats that vary in size, resulting in different alleles. Variably sized alleles can be typed rapidly from genomic DNA of individuals by the PCR. Studies of inheritance of glucokinase genes have revealed significant linkage in families with early-onset NIDDM, or MODY, and mutations have been identified within the coding region of the gene in some families. These studies are extremely encouraging, as they indicate that genes can be identified even in this heterogeneous genetic disorder. This study considers the phenotypes that result from glucokinase defects and the relationship of MODY to NIDDM, and it estimates the role of glucokinase defects in NIDDM in general.; A nonsense mutation at codon 186 in exon 5 of the gene for glucokinase, an enzyme important for glucose-induced insulin secretion, was identified in a Japanese patient with late-onset non-insulin-dependent diabetes mellitus (NIDDM). All affected members of her family were heterozygous for the mutation and had late-onset NIDDM or impaired glucose tolerance, whereas unaffected members showed normal glucose tolerance. The early insulin response to oral glucose was impaired in affected relatives, but was normal in those unaffected. These findings suggest that the glucokinase mutation raises the set-point of pancreatic beta cells for glucose-induced insulin secretion, leading to abnormal glucose tolerance in some patients with late-onset NIDDM.; Type 2 diabetes mellitus is characterised by resistance of peripheral tissues to insulin and a relative deficiency of insulin secretion. To find out which is the earliest or primary determinant of disease, we used a minimum model of glucose disposal and insulin secretion based on intravenous glucose tolerance tests to estimate insulin sensitivity (SI), glucose effectiveness (ie, insulin-independent glucose removal rate, SG), and first-phase and second-phase beta-cell responsiveness in normoglycaemic offspring of couples who both had type 2 diabetes. 155 subjects from 86 families were followed-up for 6-25 years. More than 10 years before the development of diabetes, subjects who developed the disease had lower values of both SI (mean 3.2 [SD 2.4] vs 8.1 [6.7] 10(-3) I min-1 pmol-1 insulin; p < 0.0001) and SG (1.6 [0.9] vs 2.3 [1.2] 10(-2) min-1, p < 0.0001) than did those who remained normoglycaemic). For the subjects with both SI and SG below the group median, the cumulative incidence of type 2 diabetes during the 25 years was 76% (95% confidence interval 54-99). By contrast, no subject with both SI and SG above the median developed the disease. Subjects with low SI/high SG or high SI/low SG had intermediate risks. Insulin secretion, especially first phase, tended to be increased rather than decreased in this prediabetic phase and was appropriate for the level of insulin resistance. The development of type 2 diabetes is preceded by and predicted by defects in both insulin-dependent and insulin-independent glucose uptake; the defects are detectable when the patients are normoglycaemic and in most cases more than a decade before diagnosis of disease.; The coexistence of depression and type 2 diabetes mellitus (T2DM) can significantly worsen disease prognosis and lower quality of life. Emerging evidence suggests that vitamin D deficiency contributes to the progression of T2DM and is closely associated with the development of depression. The aim of this study was to investigate the effects of cholecalciferol on depression in patients with T2DM, exploring its mechanisms by analyzing its impact on C-peptide, serotonin, and neurotrophin-3 levels. A double-blind, randomized, placebo-controlled clinical trial was conducted at Cipto Mangunkusumo General Hospital, Jakarta, Indonesia, from April 2021 to September 2022. Patients with T2DM and depressive symptoms were randomly assigned to two groups: received 4000 IU of cholecalciferol daily and received a placebo for 12 weeks. Depression was assessed using the Beck Depression Inventory-II (BDI-II) before and 12 weeks after the intervention. The levels of C-peptide, serotonin, and neurotrophin-3 were measured at the end of the fourth week of intervention using the enzyme-linked immunosorbent assay (ELISA) method. Between-group comparisons were made using independent Student t- tests and Mann-Whitney U tests. Paired Student t-tests or Wilcoxon tests were applied for within-group comparisons between pre- and post-intervention. A total of 70 T2DM patients with depression were included in this study, comprising 38 patients in the cholecalciferol group and 32 in the placebo group. C-peptide levels increased significantly in the cholecalciferol group compared to the placebo group (<i>p</i> = 0.006). No significant differences were observed in serotonin and NT-3 levels between the cholecalciferol group compared to the placebo group. The cholecalciferol group had a significantly greater reduction in BDI-II scores compared to the placebo group (<i>p</i> < 0.001). This trial highlights that taking cholecalciferol might help ease mild to moderate depression symptoms in patients with T2DM by enhancing c-peptide levels, though its effects on serotonin and neurotrophin-3 are still unclear.; Genetic diagnosis of MODY is relevant for appropriate treatment. Dominantly inherited early-onset diabetes mellitus with renal cysts suggests MODY5. Scanning the non-coding regions is important for not missing a mutation in HNF1B.; A rare loss-of-function allele p.Arg138* in SLC30A8 encoding the zinc transporter 8 (ZnT8), which is enriched in Western Finland, protects against type 2 diabetes (T2D). We recruited relatives of the identified carriers and showed that protection was associated with better insulin secretion due to enhanced glucose responsiveness and proinsulin conversion, particularly when compared with individuals matched for the genotype of a common T2D-risk allele in SLC30A8, p.Arg325. In genome-edited human induced pluripotent stem cell (iPSC)-derived β-like cells, we establish that the p.Arg138* allele results in reduced SLC30A8 expression due to haploinsufficiency. In human β cells, loss of SLC30A8 leads to increased glucose responsiveness and reduced K<sub>ATP</sub> channel function similar to isolated islets from carriers of the T2D-protective allele p.Trp325. These data position ZnT8 as an appealing target for treatment aimed at maintaining insulin secretion capacity in T2D.; Protein-coding genetic variants that strongly affect disease risk can yield relevant clues to disease pathogenesis. Here we report exome-sequencing analyses of 20,791 individuals with type 2 diabetes (T2D) and 24,440 non-diabetic control participants from 5 ancestries. We identify gene-level associations of rare variants (with minor allele frequencies of less than 0.5%) in 4 genes at exome-wide significance, including a series of more than 30 SLC30A8 alleles that conveys protection against T2D, and in 12 gene sets, including those corresponding to T2D drug targets (P = 6.1 × 10<sup>-3</sup>) and candidate genes from knockout mice (P = 5.2 × 10<sup>-3</sup>). Within our study, the strongest T2D gene-level signals for rare variants explain at most 25% of the heritability of the strongest common single-variant signals, and the gene-level effect sizes of the rare variants that we observed in established T2D drug targets will require 75,000-185,000 sequenced cases to achieve exome-wide significance. We propose a method to interpret these modest rare-variant associations and to incorporate these associations into future target or gene prioritization efforts.; Type 1 diabetes (T1D) is caused by β-cell destruction, usually leading to absolute insulin deficiency. T1D is a heterogeneous disease and is divided into two subtypes according to the presence or absence of pancreatic autoantibodies: type 1A (immune mediated) and type 1B (idiopathic). Genes such as KCNJ11 or INS, which play key roles in β-cell function, provide some insight into the pathogenesis of type 1B diabetes. In this study, we screened 110 Taiwanese children (61 males and 49 females) with T1D onset before the age of 5 years for mutations of INS and KCNJ11. We identified one missense heterozygous mutation in KCNJ11 (c.989A>G, p.Y330C) and no INS mutations among 28 probands. This is the first study to screen patients with autoantibody-negative T1D diagnosed before the age of 5 years for INS and KCNJ11 mutations in Taiwan. Although KCNJ11 mutations are always reported in patients with permanent neonatal diabetes, this gene mutation can be detected after 6 months of age. Further studies in other patients with type 1B diabetes and their families are required to elucidate the contributions of the KCNJ11 mutation to the T1D phenotype.; ABCC8 C49620T polymorphism showed possible association with T2D marked by predominance of the mutant TT genotype in T2D patients. However, the relationship between TT genotype and lipid abnormalities for possible beneficial effect on people suffering from T2D is unclear.; Genetic variants near ARAP1 (CENTD2) and STARD10 influence type 2 diabetes (T2D) risk. The risk alleles impair glucose-induced insulin secretion and, paradoxically but characteristically, are associated with decreased proinsulin:insulin ratios, indicating improved proinsulin conversion. Neither the identity of the causal variants nor the gene(s) through which risk is conferred have been firmly established. Whereas ARAP1 encodes a GTPase activating protein, STARD10 is a member of the steroidogenic acute regulatory protein (StAR)-related lipid transfer protein family. By integrating genetic fine-mapping and epigenomic annotation data and performing promoter-reporter and chromatin conformational capture (3C) studies in β cell lines, we localize the causal variant(s) at this locus to a 5 kb region that overlaps a stretch-enhancer active in islets. This region contains several highly correlated T2D-risk variants, including the rs140130268 indel. Expression QTL analysis of islet transcriptomes from three independent subject groups demonstrated that T2D-risk allele carriers displayed reduced levels of STARD10 mRNA, with no concomitant change in ARAP1 mRNA levels. Correspondingly, β-cell-selective deletion of StarD10 in mice led to impaired glucose-stimulated Ca<sup>2+</sup> dynamics and insulin secretion and recapitulated the pattern of improved proinsulin processing observed at the human GWAS signal. Conversely, overexpression of StarD10 in the adult β cell improved glucose tolerance in high fat-fed animals. In contrast, manipulation of Arap1 in β cells had no impact on insulin secretion or proinsulin conversion in mice. This convergence of human and murine data provides compelling evidence that the T2D risk associated with variation at this locus is mediated through reduction in STARD10 expression in the β cell.; Transcription factors are the major gene-regulatory proteins that recognize specific nucleotide sequences and bind to them. Missense mutations in transcription factors play a significant role in misregulation of gene expression contributing to various diseases and disorders. Understanding their structural and functional impact of the disease-causing mutations becomes prime importance in treating a disease. Commonly associated defect with the mutations of hepatocyte nuclear factor 1 beta (HNF1B) protein, a transcription factor results in maturity-onset diabetes of the young-5 (MODY-5) leading to loss of function. In the study presented, we applied a series of computational strategies to analyze the effect of mutations on protein structure or function in protein-DNA complex. The mutations from publicly available databases were retrieved and subjected to an array of in silico prediction methods. Key implementation of the present study consists of a pipeline drawn using well established in silico prediction methods of different algorithms to explain the biochemical changes impaired upon mutations in the binding sites of protein-DNA complex using HNF1B. Prediction scores obtained from the in silico tools suggested H153N and A241T as the major nsSNPs involved in destabilizing the protein. Further, high-end microscopic computational study, such as molecular dynamics simulations was utilized to relate the structural and functional effects upon mutations. Although, both the mutations exhibited similar structural differences, we observed A241T with higher destabilizing effect on the protein. The presented work is a step toward understanding the genotype-phenotype relationships in transcription factor genes using fast and accurate computational approach.; In K-ATP CHI patients managed by medical treatment only, severity is reduced over time in the majority, including those with compound heterozygous and homozygous mutations in ABCC8/KCNJ11. Severity and treatment requirement should be assessed periodically in all children with K-ATP CHI on medical therapy.; Heterozygous mutations in the gene that encodes the transcription factor hepatocyte nuclear factor 1β (HNF1B) result in a multi-system disorder. HNF1B was initially discovered as a monogenic diabetes gene; however, renal cysts are the most frequently detected feature. Other clinical features include pancreatic hypoplasia and exocrine insufficiency, genital tract malformations, abnormal liver function, cholestasis and early-onset gout. Heterozygous mutations and complete gene deletions in HNF1B each account for approximately 50% of all cases of HNF1B-associated disease and may show autosomal dominant inheritance or arise spontaneously. There is no clear genotype-phenotype correlation indicating that haploinsufficiency is the main disease mechanism. Data from animal models suggest that HNF1B is essential for several stages of pancreas and liver development. However, mice with heterozygous mutations in HNF1B show no phenotype in contrast to the phenotype seen in humans. This suggests that mouse models do not fully replicate the features of human disease and complementary studies in human systems are necessary to determine the molecular mechanisms underlying HNF1B-associated disease. This review discusses the role of HNF1B in human and murine pancreas and liver development, summarizes the disease phenotypes and identifies areas for future investigations in HNF1B-associated diabetes and liver disease.; The genetic architecture of common traits, including the number, frequency, and effect sizes of inherited variants that contribute to individual risk, has been long debated. Genome-wide association studies have identified scores of common variants associated with type 2 diabetes, but in aggregate, these explain only a fraction of the heritability of this disease. Here, to test the hypothesis that lower-frequency variants explain much of the remainder, the GoT2D and T2D-GENES consortia performed whole-genome sequencing in 2,657 European individuals with and without diabetes, and exome sequencing in 12,940 individuals from five ancestry groups. To increase statistical power, we expanded the sample size via genotyping and imputation in a further 111,548 subjects. Variants associated with type 2 diabetes after sequencing were overwhelmingly common and most fell within regions previously identified by genome-wide association studies. Comprehensive enumeration of sequence variation is necessary to identify functional alleles that provide important clues to disease pathophysiology, but large-scale sequencing does not support the idea that lower-frequency variants have a major role in predisposition to type 2 diabetes.; Genetic analysis revealed mutations in 56% of the CHI patients. ABCC8 mutations are the most frequent cause of CHI in Spain. We found ten novel mutations in the KATP channel genes. The genetic diagnosis is more likely to be achieved in patients with onset within the first week of life and in those who fail to respond to diazoxide treatment.; We performed fine mapping of 39 established type 2 diabetes (T2D) loci in 27,206 cases and 57,574 controls of European ancestry. We identified 49 distinct association signals at these loci, including five mapping in or near KCNQ1. 'Credible sets' of the variants most likely to drive each distinct signal mapped predominantly to noncoding sequence, implying that association with T2D is mediated through gene regulation. Credible set variants were enriched for overlap with FOXA2 chromatin immunoprecipitation binding sites in human islet and liver cells, including at MTNR1B, where fine mapping implicated rs10830963 as driving T2D association. We confirmed that the T2D risk allele for this SNP increases FOXA2-bound enhancer activity in islet- and liver-derived cells. We observed allele-specific differences in NEUROD1 binding in islet-derived cells, consistent with evidence that the T2D risk allele increases islet MTNR1B expression. Our study demonstrates how integration of genetic and genomic information can define molecular mechanisms through which variants underlying association signals exert their effects on disease.; NA; Type 2 diabetes (T2D) is characterized by chronic hyperglycemia resulting from a deficiency in insulin signaling, because of insulin resistance and/or defects in insulin secretion; it is also associated with increases in glucagon and endogenous glucose production (EGP). Gliflozins, including dapagliflozin, are a new class of approved oral antidiabetic agents that specifically inhibit sodium-glucose co-transporter 2 (SGLT2) function in the kidney, thus preventing renal glucose reabsorption and increasing glycosuria in diabetic individuals while reducing hyperglycemia. However, gliflozin treatment in subjects with T2D increases both plasma glucagon and EGP by unknown mechanisms. In spite of the rise in EGP, T2D patients treated with gliflozin have lower blood glucose levels than those receiving placebo, possibly because of increased glycosuria; however, the resulting increase in plasma glucagon levels represents a possible concerning side effect, especially in a patient population already affected by hyperglucagonemia. Here we demonstrate that SGLT2 is expressed in glucagon-secreting alpha cells of the pancreatic islets. We further found that expression of SLC5A2 (which encodes SGLT2) was lower and glucagon (GCG) gene expression was higher in islets from T2D individuals and in normal islets exposed to chronic hyperglycemia than in islets from non-diabetics. Moreover, hepatocyte nuclear factor 4-α (HNF4A) is specifically expressed in human alpha cells, in which it controls SLC5A2 expression, and its expression is downregulated by hyperglycemia. In addition, inhibition of either SLC5A2 via siRNA-induced gene silencing or SGLT2 via dapagliflozin treatment in human islets triggered glucagon secretion through KATP channel activation. Finally, we found that dapagliflozin treatment further promotes glucagon secretion and hepatic gluconeogenesis in healthy mice, thereby limiting the decrease of plasma glucose induced by fasting. Collectively, these results identify a heretofore unknown role of SGLT2 and designate dapagliflozin an alpha cell secretagogue.; Heterozygous mutations in the gene that encodes the transcription factor hepatocyte nuclear factor 1β (HNF1B) represent the most common known monogenic cause of developmental kidney disease. Renal cysts are the most frequently detected feature of HNF1B-associated kidney disease; however, other structural abnormalities, including single kidneys and renal hypoplasia, and electrolyte abnormalities can also occur. Extra-renal phenotypes might also be observed; consequently, HNF1B-associated disease is considered a multi-system disorder. Other clinical features include early-onset diabetes mellitus, pancreatic hypoplasia, genital tract malformations, abnormal liver function and early-onset gout. Heterozygous mutations in the coding region or splice sites of HNF1B, and complete gene deletion, each account for ∼50% of all cases of HNF1B-associated disease, respectively, and often arise spontaneously. There is no clear genotype-phenotype correlation, consistent with haploinsufficiency as the disease mechanism. Data from animal models suggest that HNF1B has an important function during several stages of nephrogenesis; however, the precise signalling pathways remain to be elucidated. This Review discusses the genetics and molecular pathways that lead to disease development, summarizes the reported renal and extra-renal phenotypes, and identifies areas for future research in HNF1B-associated disease.; Hepatocyte nuclear factor 1-β (HNF1B) defects cause renal cysts and diabetes syndrome (RCAD), or HNF1B-maturity-onset diabetes of the young. However, the hepatic phenotype of HNF1B variants is not well studied. We present a female neonate born small for her gestational age [birth weight 2360 g; -2.02 standard deviations (SD) and birth length 45 cm; -2.40 SD at the 38(th) gestational week]. She developed neonatal cholestasis due to biliary atresia and required surgical intervention (portoenterostomy) when 32-d old. Following the operation, icterus resolved, but laboratory signs of liver dysfunction persisted. She had hyperechogenic kidneys prenatally with bilateral renal cysts and pancreatic hypoplasia postnatally that led to the diagnosis of an HNF1B deletion. This represents the most severe hepatic phenotype of an HNF1B variant recognized thus far. A review of 12 published cases with hepatic phenotypes of HNF1B defects allowed us to distinguish three severity levels, ranging from neonatal cholestasis through adult-onset cholestasis to non-cholestatic liver impairment, all of these are associated with congenital renal cysts and mostly with diabetes later in life. We conclude that to detect HNF1B variants, neonates with cholestasis should be checked for the presence of renal cysts, with special focus on those who are born small for their gestational age. Additionally, patients with diabetes and renal cysts at any age who develop cholestasis and/or exocrine pancreatic insufficiency should be tested for HNF1B variants as the true etiological factor of all disease components. Further observations are needed to confirm the potential reversibility of cholestasis in infancy in HNF1B mutation/deletion carriers.; The prevalence of HNF1B mutations and the relative contribution of hypomagnesemia to its symptoms are underestimated. Therefore, patients with primary renal magnesium wasting should be tested for HNF1B mutations to ensure early detection and optimal management of ADTKD-HNF1B.; HNF1B-related disease is an emerging condition characterized by an autosomal-dominant inheritance, a 50% rate of de novo mutations, and a highly variable phenotype (renal involvement, maturity-onset diabetes of the young type 5, pancreatic hypoplasia, and urogenital tract and liver test abnormalities). Given the current lack of pathognomonic characteristics and the wide overlap with other conditions, a genetic test is the diagnostic gold standard. However, pre-genetic screening is mandatory because genetic testing has substantial costs. Our aim was to develop a HNF1B score, based on clinical, imaging, and biological variables, as a pivotal tool for rational genetic testing. A score was created using a weighted combination of the most discriminative characteristics based on the frequency and specificity in published series. The HNF1B score is calculated upon 17 items including antenatal discovery, family history, and organ involvement (kidney, pancreas, liver, and genital tract). The performance of the score was assessed by a ROC curve analysis in a 433-individual cohort containing 56 HNF1B cases. The HNF1B score efficiently and significantly discriminated between mutated and nonmutated cases (AUC 0.78). The optimal cutoff threshold for the negative predictive value to rule out HNF1B mutations in a suspected individual was 8 (sensitivity 98.2%, specificity 41.1%, and negative predictive value over 99%). Thus, the HNF1B score is a simple and accurate tool to provide a more rational approach to select patients for HNF1B screening.; Loss-of-function mutations protective against human disease provide in vivo validation of therapeutic targets, but none have yet been described for type 2 diabetes (T2D). Through sequencing or genotyping of ~150,000 individuals across 5 ancestry groups, we identified 12 rare protein-truncating variants in SLC30A8, which encodes an islet zinc transporter (ZnT8) and harbors a common variant (p.Trp325Arg) associated with T2D risk and glucose and proinsulin levels. Collectively, carriers of protein-truncating variants had 65% reduced T2D risk (P = 1.7 × 10(-6)), and non-diabetic Icelandic carriers of a frameshift variant (p.Lys34Serfs*50) demonstrated reduced glucose levels (-0.17 s.d., P = 4.6 × 10(-4)). The two most common protein-truncating variants (p.Arg138* and p.Lys34Serfs*50) individually associate with T2D protection and encode unstable ZnT8 proteins. Previous functional study of SLC30A8 suggested that reduced zinc transport increases T2D risk, and phenotypic heterogeneity was observed in mouse Slc30a8 knockouts. In contrast, loss-of-function mutations in humans provide strong evidence that SLC30A8 haploinsufficiency protects against T2D, suggesting ZnT8 inhibition as a therapeutic strategy in T2D prevention.; In patients with type 2 diabetes, empagliflozin-induced glycosuria improved β cell function and insulin sensitivity, despite the fall in insulin secretion and tissue glucose disposal and the rise in EGP after one dose, thereby lowering fasting and postprandial glycemia. Chronic dosing shifted substrate utilization from carbohydrate to lipid. Trial registration. ClinicalTrials.Gov NCT01248364 (EudraCT no. 2010-018708-99). Funding. This study was funded by Boehringer Ingelheim.; Performing genetic studies in multiple human populations can identify disease risk alleles that are common in one population but rare in others, with the potential to illuminate pathophysiology, health disparities, and the population genetic origins of disease alleles. Here we analysed 9.2 million single nucleotide polymorphisms (SNPs) in each of 8,214 Mexicans and other Latin Americans: 3,848 with type 2 diabetes and 4,366 non-diabetic controls. In addition to replicating previous findings, we identified a novel locus associated with type 2 diabetes at genome-wide significance spanning the solute carriers SLC16A11 and SLC16A13 (P = 3.9 × 10(-13); odds ratio (OR) = 1.29). The association was stronger in younger, leaner people with type 2 diabetes, and replicated in independent samples (P = 1.1 × 10(-4); OR = 1.20). The risk haplotype carries four amino acid substitutions, all in SLC16A11; it is present at ~50% frequency in Native American samples and ~10% in east Asian, but is rare in European and African samples. Analysis of an archaic genome sequence indicated that the risk haplotype introgressed into modern humans via admixture with Neanderthals. The SLC16A11 messenger RNA is expressed in liver, and V5-tagged SLC16A11 protein localizes to the endoplasmic reticulum. Expression of SLC16A11 in heterologous cells alters lipid metabolism, most notably causing an increase in intracellular triacylglycerol levels. Despite type 2 diabetes having been well studied by genome-wide association studies in other populations, analysis in Mexican and Latin American individuals identified SLC16A11 as a novel candidate gene for type 2 diabetes with a possible role in triacylglycerol metabolism.; Leprechaunism and Rabson-Mendenhall syndrome are very rare and difficult to diagnose. Diagnosis is currently based mostly on clinical criteria. Clinical availability of DNA sequencing can provide an objective way of confirming or excluding the diagnosis.; Genotype to phenotype correlations were most successful in children with GLUD1, GCK, and recessive KATP mutations. Correlations were complicated by the high frequency of novel missense KATP mutations that were uncharacterized, because such defects might be either recessive or dominant and, if dominant, be either responsive or unresponsive to diazoxide. Accurate and timely prediction of phenotype based on genotype is critical to limit exposure to persistent hypoglycemia in infants and children with congenital HI.; NA; NA; NA; Genome-wide association studies (GWAS) have consistently implicated noncoding variation within the TCF7L2 locus with type 2 diabetes (T2D) risk. While this locus represents the strongest genetic determinant for T2D risk in humans, it remains unclear how these noncoding variants affect disease etiology. To test the hypothesis that the T2D-associated interval harbors cis-regulatory elements controlling TCF7L2 expression, we conducted in vivo transgenic reporter assays to characterize the TCF7L2 regulatory landscape. We found that the 92-kb genomic interval associated with T2D harbors long-range enhancers regulating various aspects of the spatial-temporal expression patterns of TCF7L2, including expression in tissues involved in the control of glucose homeostasis. By selectively deleting this interval, we establish a critical role for these enhancers in robust TCF7L2 expression. To further determine whether variation in Tcf7l2 expression may lead to diabetes, we developed a Tcf7l2 copy-number allelic series in mice. We show that a null Tcf7l2 allele leads, in a dose-dependent manner, to lower glycemic profiles. Tcf7l2 null mice also display enhanced glucose tolerance coupled to significantly lowered insulin levels, suggesting that these mice are protected against T2D. Confirming these observations, transgenic mice harboring multiple Tcf7l2 copies and overexpressing this gene display reciprocal phenotypes, including glucose intolerance. These results directly demonstrate that Tcf7l2 plays a role in regulating glucose tolerance, suggesting that overexpression of this gene is associated with increased risk of T2D. These data highlight the role of enhancer elements as mediators of T2D risk in humans, strengthening the evidence that variation in cis-regulatory elements may be a paradigm for genetic predispositions to common disease.; These results demonstrate that some dominant mutations of SUR1 can cause diazoxide-unresponsive hyperinsulinism. In vitro expression studies may be helpful in distinguishing such mutations from dominant mutations of SUR1 associated with diazoxide-responsive disease.; LKB1 is a 'master' protein kinase implicated in the regulation of metabolism, cell proliferation, cell polarity and tumorigenesis. However, the long-term role of LKB1 in hepatic function is unknown. In the present study, it is shown that hepatic LKB1 plays a key role in liver cellular architecture and metabolism. We report that liver-specific deletion of LKB1 in mice leads to defective canaliculi and bile duct formation, causing impaired bile acid clearance and subsequent accumulation of bile acids in serum and liver. Concomitant with this, it was found that the majority of BSEP (bile salt export pump) was retained in intracellular pools rather than localized to the canalicular membrane in hepatocytes from LLKB1KO (liver-specific Lkb1-knockout) mice. Together, these changes resulted in toxic accumulation of bile salts, reduced liver function and failure to thrive. Additionally, circulating LDL (low-density lipoprotein)-cholesterol and non-esterified cholesterol levels were increased in LLKB1KO mice with an associated alteration in red blood cell morphology and development of hyperbilirubinaemia. These results indicate that LKB1 plays a critical role in bile acid homoeostasis and that lack of LKB1 in the liver results in cholestasis. These findings indicate a novel key role for LKB1 in the development of hepatic morphology and membrane targeting of canalicular proteins.; Metformin is the most commonly used pharmacological therapy for type 2 diabetes. We report a genome-wide association study for glycemic response to metformin in 1,024 Scottish individuals with type 2 diabetes with replication in two cohorts including 1,783 Scottish individuals and 1,113 individuals from the UK Prospective Diabetes Study. In a combined meta-analysis, we identified a SNP, rs11212617, associated with treatment success (n = 3,920, P = 2.9 × 10(-9), odds ratio = 1.35, 95% CI 1.22-1.49) at a locus containing ATM, the ataxia telangiectasia mutated gene. In a rat hepatoma cell line, inhibition of ATM with KU-55933 attenuated the phosphorylation and activation of AMP-activated protein kinase in response to metformin. We conclude that ATM, a gene known to be involved in DNA repair and cell cycle control, plays a role in the effect of metformin upstream of AMP-activated protein kinase, and variation in this gene alters glycemic response to metformin.; It was recently reported that GCKR rs780094 was associated with fasting plasma glucose (FPG) and triglyceride (TG) levels in various ethnic populations (A allele for low FPG and high TG). An association between GCKR rs780094 and type 2 diabetes mellitus (T2DM) (A allele for low risk) has also been reported. We examined the association between GCKR rs780094 and T2DM in Japanese subjects by analyzing 488 cases and 398 controls. A meta-analysis was performed involving two previous association studies. We also analyzed the association between the single-nucleotide polymorphism and clinical parameters in the general Japanese population (n=1854). In the case-control study, the A allele of GCKR rs780094 was associated with a reduced risk of T2DM (odds ratio=0.711 (95% confidence interval=0.589-0.859), P=4.2 × 10(-4)). A meta-analysis confirmed the association of GCKR rs780094 with T2DM susceptibility. In the general Japanese population, subjects with the A/A genotype had lower levels of FPG, fasting plasma insulin and homeostasis model assessment of insulin resistance than those with the G/G genotype. Conversely, subjects with the A/A genotype had higher levels of TG than those with the G/G genotype. We replicated GCKR rs780094 as a marker of T2DM susceptibility in Japanese subjects. This suggests that GCKR rs780094 is a common variant for T2DM susceptibility in various ethnic groups.; The pancreatic beta-cell ATP-sensitive potassium (K(ATP)) channel is a multimeric protein complex composed of four inwardly rectifying potassium channel (Kir6.2) and four sulfonylurea receptor 1 (SUR1) subunits. K(ATP) channels play a key role in glucose-stimulated insulin secretion by linking glucose metabolism to membrane excitability. Many SUR1 and Kir6.2 mutations reduce channel function by disrupting channel biogenesis and processing, resulting in insulin secretion disease. To better understand the mechanisms governing K(ATP) channel biogenesis, a proteomics approach was used to identify chaperone proteins associated with K(ATP) channels. We report that chaperone proteins heat-shock protein (Hsp)90, heat-shock cognate protein (Hsc)70, and Hsp40 are associated with beta-cell K(ATP) channels. Pharmacologic inhibition of Hsp90 function by geldanamycin reduces, whereas overexpression of Hsp90 increases surface expression of wild-type K(ATP) channels. Coimmunoprecipitation data indicate that channel association with the Hsp90 complex is mediated through SUR1. Accordingly, manipulation of Hsp90 protein expression or function has significant effects on the biogenesis efficiency of SUR1, but not Kir6.2, expressed alone. Interestingly, overexpression of Hsp90 selectively improved surface expression of mutant channels harboring a subset of disease-causing SUR1 processing mutations. Our study demonstrates that Hsp90 regulates biogenesis efficiency of heteromeric K(ATP) channels via SUR1, thereby affecting functional expression of the channel in beta-cell membrane.; Copy number variants (CNVs) account for a major proportion of human genetic polymorphism and have been predicted to have an important role in genetic susceptibility to common disease. To address this we undertook a large, direct genome-wide study of association between CNVs and eight common human diseases. Using a purpose-designed array we typed approximately 19,000 individuals into distinct copy-number classes at 3,432 polymorphic CNVs, including an estimated approximately 50% of all common CNVs larger than 500 base pairs. We identified several biological artefacts that lead to false-positive associations, including systematic CNV differences between DNAs derived from blood and cell lines. Association testing and follow-up replication analyses confirmed three loci where CNVs were associated with disease-IRGM for Crohn's disease, HLA for Crohn's disease, rheumatoid arthritis and type 1 diabetes, and TSPAN8 for type 2 diabetes-although in each case the locus had previously been identified in single nucleotide polymorphism (SNP)-based studies, reflecting our observation that most common CNVs that are well-typed on our array are well tagged by SNPs and so have been indirectly explored through SNP studies. We conclude that common CNVs that can be typed on existing platforms are unlikely to contribute greatly to the genetic basis of common human diseases.; Tissue-specific transcriptional regulation is central to human disease. To identify regulatory DNA active in human pancreatic islets, we profiled chromatin by formaldehyde-assisted isolation of regulatory elements coupled with high-throughput sequencing (FAIRE-seq). We identified approximately 80,000 open chromatin sites. Comparison of FAIRE-seq data from islets to that from five non-islet cell lines revealed approximately 3,300 physically linked clusters of islet-selective open chromatin sites, which typically encompassed single genes that have islet-specific expression. We mapped sequence variants to open chromatin sites and found that rs7903146, a TCF7L2 intronic variant strongly associated with type 2 diabetes, is located in islet-selective open chromatin. We found that human islet samples heterozygous for rs7903146 showed allelic imbalance in islet FAIRE signals and that the variant alters enhancer activity, indicating that genetic variation at this locus acts in cis with local chromatin and regulatory changes. These findings illuminate the tissue-specific organization of cis-regulatory elements and show that FAIRE-seq can guide the identification of regulatory variants underlying disease susceptibility.; We provide evidence that IR in humans may be related to coordinated changes in multiple microRNAs, which act to target relevant signaling pathways. It would appear that miRNAs can produce marked changes in target protein abundance in vivo by working in a combinatorial manner. Thus, miRNA detection represents a new molecular biomarker strategy for insulin resistance, where micrograms of patient material is needed to monitor efficacy during drug or life-style interventions.; Epidemiological studies consistently show that circulating sex hormone binding globulin (SHBG) levels are lower in type 2 diabetes patients than non-diabetic individuals, but the causal nature of this association is controversial. Genetic studies can help dissect causal directions of epidemiological associations because genotypes are much less likely to be confounded, biased or influenced by disease processes. Using this Mendelian randomization principle, we selected a common single nucleotide polymorphism (SNP) near the SHBG gene, rs1799941, that is strongly associated with SHBG levels. We used data from this SNP, or closely correlated SNPs, in 27 657 type 2 diabetes patients and 58 481 controls from 15 studies. We then used data from additional studies to estimate the difference in SHBG levels between type 2 diabetes patients and controls. The SHBG SNP rs1799941 was associated with type 2 diabetes [odds ratio (OR) 0.94, 95% CI: 0.91, 0.97; P = 2 x 10(-5)], with the SHBG raising allele associated with reduced risk of type 2 diabetes. This effect was very similar to that expected (OR 0.92, 95% CI: 0.88, 0.96), given the SHBG-SNP versus SHBG levels association (SHBG levels are 0.2 standard deviations higher per copy of the A allele) and the SHBG levels versus type 2 diabetes association (SHBG levels are 0.23 standard deviations lower in type 2 diabetic patients compared to controls). Results were very similar in men and women. There was no evidence that this variant is associated with diabetes-related intermediate traits, including several measures of insulin secretion and resistance. Our results, together with those from another recent genetic study, strengthen evidence that SHBG and sex hormones are involved in the aetiology of type 2 diabetes.; Effects of susceptibility variants may depend on from which parent they are inherited. Although many associations between sequence variants and human traits have been discovered through genome-wide associations, the impact of parental origin has largely been ignored. Here we show that for 38,167 Icelanders genotyped using single nucleotide polymorphism (SNP) chips, the parental origin of most alleles can be determined. For this we used a combination of genealogy and long-range phasing. We then focused on SNPs that associate with diseases and are within 500 kilobases of known imprinted genes. Seven independent SNP associations were examined. Five-one with breast cancer, one with basal-cell carcinoma and three with type 2 diabetes-have parental-origin-specific associations. These variants are located in two genomic regions, 11p15 and 7q32, each harbouring a cluster of imprinted genes. Furthermore, we observed a novel association between the SNP rs2334499 at 11p15 and type 2 diabetes. Here the allele that confers risk when paternally inherited is protective when maternally transmitted. We identified a differentially methylated CTCF-binding site at 11p15 and demonstrated correlation of rs2334499 with decreased methylation of that site.; Common variants in the transcription factor 7-like 2 (TCF7L2) gene have been identified as the strongest genetic risk factors for type 2 diabetes (T2D). However, the mechanisms by which these non-coding variants increase risk for T2D are not well-established. We used 13 expression assays to survey mRNA expression of multiple TCF7L2 splicing forms in up to 380 samples from eight types of human tissue (pancreas, pancreatic islets, colon, liver, monocytes, skeletal muscle, subcutaneous adipose tissue and lymphoblastoid cell lines) and observed a tissue-specific pattern of alternative splicing. We tested whether the expression of TCF7L2 splicing forms was associated with single nucleotide polymorphisms (SNPs), rs7903146 and rs12255372, located within introns 3 and 4 of the gene and most strongly associated with T2D. Expression of two splicing forms was lower in pancreatic islets with increasing counts of T2D-associated alleles of the SNPs: a ubiquitous splicing form (P = 0.018 for rs7903146 and P = 0.020 for rs12255372) and a splicing form found in pancreatic islets, pancreas and colon but not in other tissues tested here (P = 0.009 for rs12255372 and P = 0.053 for rs7903146). Expression of this form in glucose-stimulated pancreatic islets correlated with expression of proinsulin (r(2) = 0.84-0.90, P < 0.00063). In summary, we identified a tissue-specific pattern of alternative splicing of TCF7L2. After adjustment for multiple tests, no association between expression of TCF7L2 in eight types of human tissue samples and T2D-associated genetic variants remained significant. Alternative splicing of TCF7L2 in pancreatic islets warrants future studies. GenBank Accession Numbers: FJ010164-FJ010174.; Low circulating levels of sex hormone-binding globulin are a strong predictor of the risk of type 2 diabetes in women and men. The clinical usefulness of both SHBG genotypes and plasma levels in stratification and intervention for the risk of type 2 diabetes warrants further examination.; Minimization of tacrolimus exposure and withdrawal of steroids considerably reduced the patient's insulin requirement, and cholestasis-related pruritus was dramatically improved by administration of ursodeoxycholic acid. Renal ultrasonography and screening for the HNF1B molecular abnormality were offered to the patient's relatives.; Over the past two years, there has been a spectacular change in the capacity to identify common genetic variants that contribute to predisposition to complex multifactorial phenotypes such as type 2 diabetes (T2D). The principal advance has been the ability to undertake surveys of genome-wide association in large study samples. Through these and related efforts, approximately 20 common variants are now robustly implicated in T2D susceptibility. Current developments, for example in high-throughput resequencing, should help to provide a more comprehensive view of T2D susceptibility in the near future. Although additional investigation is needed to define the causal variants within these novel T2D-susceptibility regions, to understand disease mechanisms and to effect clinical translation, these findings are already highlighting the predominant contribution of defects in pancreatic beta-cell function to the development of T2D.; A genotype score based on 18 risk alleles predicted new cases of diabetes in the community but provided only a slightly better prediction of risk than knowledge of common risk factors alone.; As compared with clinical risk factors alone, common genetic variants associated with the risk of diabetes had a small effect on the ability to predict the future development of type 2 diabetes. The value of genetic factors increased with an increasing duration of follow-up.; We conducted a genome-wide association study using 207,097 SNP markers in Japanese individuals with type 2 diabetes and unrelated controls, and identified KCNQ1 (potassium voltage-gated channel, KQT-like subfamily, member 1) to be a strong candidate for conferring susceptibility to type 2 diabetes. We detected consistent association of a SNP in KCNQ1 (rs2283228) with the disease in several independent case-control studies (additive model P = 3.1 x 10(-12); OR = 1.26, 95% CI = 1.18-1.34). Several other SNPs in the same linkage disequilibrium (LD) block were strongly associated with type 2 diabetes (additive model: rs2237895, P = 7.3 x 10(-9); OR = 1.32, 95% CI = 1.20-1.45, rs2237897, P = 6.8 x 10(-13); OR = 1.41, 95% CI = 1.29-1.55). The association of these SNPs with type 2 diabetes was replicated in samples from Singaporean (additive model: rs2237895, P = 8.5 x 10(-3); OR = 1.14, rs2237897, P = 2.4 x 10(-4); OR = 1.22) and Danish populations (additive model: rs2237895, P = 3.7 x 10(-11); OR = 1.24, rs2237897, P = 1.2 x 10(-4); OR = 1.36).; Congenital hyperinsulinism is a condition of dysregulated insulin secretion often caused by inactivating mutations of the ATP-sensitive K+ (KATP) channel in the pancreatic beta cell. Though most disease-causing mutations of the 2 genes encoding KATP subunits, ABCC8 (SUR1) and KCNJ11 (Kir6.2), are recessively inherited, some cases of dominantly inherited inactivating mutations have been reported. To better understand the differences between dominantly and recessively inherited inactivating KATP mutations, we have identified and characterized 16 families with 14 different dominantly inherited KATP mutations, including a total of 33 affected individuals. The 16 probands presented with hypoglycemia at ages from birth to 3.3 years, and 15 of 16 were well controlled on diazoxide, a KATP channel agonist. Of 29 adults with mutations, 14 were asymptomatic. In contrast to a previous report of increased diabetes risk in dominant KATP hyperinsulinism, only 4 of 29 adults had diabetes. Unlike recessive mutations, dominantly inherited KATP mutant subunits trafficked normally to the plasma membrane when expressed in COSm6 cells. Dominant mutations also resulted in different channel-gating defects, as dominant ABCC8 mutations diminished channel responses to magnesium adenosine diphosphate or diazoxide, while dominant KCNJ11 mutations impaired channel opening, even in the absence of nucleotides. These data highlight distinctive features of dominant KATP hyperinsulinism relative to the more common and more severe recessive form, including retention of normal subunit trafficking, impaired channel activity, and a milder hypoglycemia phenotype that may escape detection in infancy and is often responsive to diazoxide medical therapy, without the need for surgical pancreatectomy.; Some of these variants represent common type 2 diabetes-susceptibility genes in both Japanese and Europeans.; We validate the association of LIPC promoter variation with fasting serum HDL-c and present data supporting an interaction with physical activity implying an increased effect on HDL-c in vigorous physically active subjects carrying the -250 A allele. This interaction may have potential implications for public health and disease prevention.; Recently, the hematopoietically expressed homeobox (HHEX) gene, encoding a transcription factor, was identified in a large genome-wide scan in French individuals as a type 2 diabetes (T2D)-susceptibility locus. We aimed to check whether this finding could be replicated in a Dutch T2D cohort. Two common variants (rs7923837 and rs1111875) located near the HHEX gene were genotyped in 501 unrelated T2D patients and in 920 healthy controls. The major alleles of both variants were overrepresented in T2D cases compared with controls (66.7 vs 64.1%, P=0.16 for rs7923837 and 64.6 vs 60.4%, P=0.027 for rs1111875). For both polymorphisms, the risk for T2D was significantly increased in carriers of the major alleles (rs7923837: odds ratio (OR): 1.57, 95% confidence interval (CI): 1.08-2.27, P=0.017 and rs1111875: OR: 1.68, 95% CI: 1.19-2.35, P=0.003). The haplotype analysis did not reveal a risk haplotype that provided stronger evidence for association with T2D than each variant individually. Assuming a dominant genetic model, the population-attributable risks for diabetes due to the at-risk alleles of rs7923837 and rs1111875 were estimated to be 33 and 36%, respectively. These data provide evidence that variants near the HHEX gene contribute to the risk of T2D in a Dutch population.; Chronic hyperglycemia contributes to the development of diabetes-associated complications. Increases in the concentration of circulating glucose activate the hexosamine biosynthetic pathway (HBP) and promote the O-glycosylation of proteins by O-glycosyl transferase (OGT). We show that OGT triggered hepatic gluconeogenesis through the O-glycosylation of the transducer of regulated cyclic adenosine monophosphate response element-binding protein (CREB) 2 (TORC2 or CRTC2). CRTC2 was O-glycosylated at sites that normally sequester CRTC2 in the cytoplasm through a phosphorylation-dependent mechanism. Decreasing amounts of O-glycosylated CRTC2 by expression of the deglycosylating enzyme O-GlcNAcase blocked effects of glucose on gluconeogenesis, demonstrating the importance of the HBP in the development of glucose intolerance.; The GCKR rs780094 polymorphism, or another variant with which it is in tight linkage disequilibrium, is likely to increase glucokinase regulatory protein activity to induce improved glycaemic regulation at the expense of hypertriacylglycerolaemia as reflected in the present study of 16,853 Danes. We also suggest an additive effect of GCK and GCKR risk alleles on [corrected] serum insulin release.; Micro-RNAs (miRNAs) have been suggested to play pivotal roles in multifarious diseases associated with the posttranscriptional regulation of protein-coding genes. In this study, we aimed to investigate the function of miRNAs in type 2 diabetes mellitus. The miRNAs expression profiles were examined by miRNA microarray analysis of skeletal muscles from healthy and Goto-Kakizaki rats. We identified four up-regulated miRNAs, and 11 miRNAs that were down-regulated relative to normal individuals. Among induced miRNAs were three paralogs of miR-29, miR-29a, miR-29b, and miR-29c. Northern blotting further confirmed their elevated expression in three important target tissues of insulin action: muscle, fat, and liver of diabetic rats. Adenovirus-mediated overexpression of miR-29a/b/c in 3T3-L1 adipocytes could largely repress insulin-stimulated glucose uptake, presumably through inhibiting Akt activation. The increase in miR-29 level caused insulin resistance, similar to that of incubation with high glucose and insulin in combination, which, in turn, induced miR-29a and miR-29b expression. In this paper, we demonstrate that Akt is not the direct target gene of miR-29 and that the negative effects of miR-29 on insulin signaling might be mediated by other unknown intermediates. Taken together, these data reveal the crucial role of miR-29 in type 2 diabetes.; Gain-of-function mutations in the genes encoding the ATP-sensitive potassium (K(ATP)) channel subunits Kir6.2 (KCNJ11) and SUR1 (ABCC8) are a common cause of neonatal diabetes mellitus. Here we investigate the molecular mechanism by which two heterozygous mutations in the second nucleotide-binding domain (NBD2) of SUR1 (R1380L and R1380C) separately cause neonatal diabetes. SUR1 is a channel regulator that modulates the gating of the pore formed by Kir6.2. K(ATP) channel activity is inhibited by ATP binding to Kir6.2 but is stimulated by MgADP binding, or by MgATP binding and hydrolysis, at the NBDs of SUR1. Functional analysis of purified NBD2 showed that each mutation enhances MgATP hydrolysis by purified isolated fusion proteins of maltose-binding protein and NBD2. Inhibition of ATP hydrolysis by MgADP was unaffected by mutation of R1380, but inhibition by beryllium fluoride (which traps the ATPase cycle in the prehydrolytic state) was reduced. MgADP-dependent activation of K(ATP) channel activity was unaffected. These data suggest that the R1380L and R1380C mutations enhance the off-rate of P(i), thereby enhancing the hydrolytic rate. Molecular modeling studies supported this idea. Because mutant channels were inhibited less strongly by MgATP, this would increase K(ATP) currents in pancreatic beta cells, thus reducing insulin secretion and producing diabetes.; Our data from two independent cohorts indicate that the variability of the IL6 gene is significantly associated with adiposity. Such associations are less likely to be caused by polymorphism -174G>C.; Our results are consistent with others' findings that variations at TCF7L2 contribute to T2D, including Chinese. The presence of association signals spanning several LD blocks warrants further examination of extended regions to reveal the causal variant(s) for this important T2D gene.; We studied genes involved in pancreatic beta cell function and survival, identifying associations between SNPs in WFS1 and diabetes risk in UK populations that we replicated in an Ashkenazi population and in additional UK studies. In a pooled analysis comprising 9,533 cases and 11,389 controls, SNPs in WFS1 were strongly associated with diabetes risk. Rare mutations in WFS1 cause Wolfram syndrome; using a gene-centric approach, we show that variation in WFS1 also predisposes to common type 2 diabetes.; Genetic variants in the gene encoding for transcription factor-7-like 2 (TCF7L2) have been associated with type 2 diabetes (T2D) and impaired beta cell function, but the mechanisms have remained unknown. We therefore studied prospectively the ability of common variants in TCF7L2 to predict future T2D and explored the mechanisms by which they would do this. Scandinavian subjects followed for up to 22 years were genotyped for 3 SNPs (rs7903146, rs12255372, and rs10885406) in TCF7L2, and a subset of them underwent extensive metabolic studies. Expression of TCF7L2 was related to genotype and metabolic parameters in human islets. The CT/TT genotypes of SNP rs7903146 strongly predicted future T2D in 2 independent cohorts (Swedish and Finnish). The risk T allele was associated with impaired insulin secretion, incretin effects, and enhanced rate of hepatic glucose production. TCF7L2 expression in human islets was increased 5-fold in T2D, particularly in carriers of the TT genotype. Overexpression of TCF7L2 in human islets reduced glucose-stimulated insulin secretion. In conclusion, the increased risk of T2D conferred by variants in TCF7L2 involves the enteroinsular axis, enhanced expression of the gene in islets, and impaired insulin secretion.; We conducted a genome-wide association study for type 2 diabetes (T2D) in Icelandic cases and controls, and we found that a previously described variant in the transcription factor 7-like 2 gene (TCF7L2) gene conferred the most significant risk. In addition to confirming two recently identified risk variants, we identified a variant in the CDKAL1 gene that was associated with T2D in individuals of European ancestry (allele-specific odds ratio (OR) = 1.20 (95% confidence interval, 1.13-1.27), P = 7.7 x 10(-9)) and individuals from Hong Kong of Han Chinese ancestry (OR = 1.25 (1.11-1.40), P = 0.00018). The genotype OR of this variant suggested that the effect was substantially stronger in homozygous carriers than in heterozygous carriers. The ORs for homozygotes were 1.50 (1.31-1.72) and 1.55 (1.23-1.95) in the European and Hong Kong groups, respectively. The insulin response for homozygotes was approximately 20% lower than for heterozygotes or noncarriers, suggesting that this variant confers risk of T2D through reduced insulin secretion.; The role of genes in normal birth-weight variation is poorly understood, and it has been suggested that the genetic component of fetal growth is small. Type 2 diabetes genes may influence birth weight through maternal genotype, by increasing maternal glycemia in pregnancy, or through fetal genotype, by altering fetal insulin secretion. We aimed to assess the role of the recently described type 2 diabetes gene TCF7L2 in birth weight. We genotyped the polymorphism rs7903146 in 15,709 individuals whose birth weight was available from six studies and in 8,344 mothers from three studies. Each fetal copy of the predisposing allele was associated with an 18-g (95% confidence interval [CI] 7-29 g) increase in birth weight (P=.001) and each maternal copy with a 30-g (95% CI 15-45 g) increase in offspring birth weight (P=2.8x10-5). Stratification by fetal genotype suggested that the association was driven by maternal genotype (31-g [95% CI 9-48 g] increase per allele; corrected P=.003). Analysis of diabetes-related traits in 10,314 nondiabetic individuals suggested the most likely mechanism is that the risk allele reduces maternal insulin secretion (disposition index reduced by ~0.15 standard deviation; P=1x10-4), which results in increased maternal glycemia in pregnancy and hence increased offspring birth weight. We combined information with the other common variant known to alter fetal growth, the -30G-->A polymorphism of glucokinase (rs1799884). The 4% of offspring born to mothers carrying three or four risk alleles were 119 g (95% CI 62-172 g) heavier than were the 32% born to mothers with none (for overall trend, P=2x10-7), comparable to the impact of maternal smoking during pregnancy. In conclusion, we have identified the first type 2 diabetes-susceptibility allele to be reproducibly associated with birth weight. Common gene variants can substantially influence normal birth-weight variation.; NA; These results indicate that TCF7L2 might be a strong candidate for conferring susceptibility to type 2 diabetes across different ethnicities.; Polymorphisms within the transcription factor 7-like 2 gene (TCF7L2) have been associated with type 2 diabetes (T2D) in several recent studies. We characterized three of these polymorphisms (rs12255372, rs7903146 and the microsatellite DG10S478) in an admixed sample of 286 patients with T2D and 275 controls from Mexico City. We also analyzed three samples representative of the relevant parental populations: Native Americans from the state of Guerrero (Mexico), Spanish from Valencia and Nigerians (Bini from the Edo region). In order to minimize potential confounding because of the presence of population stratification in the sample, we evaluated the association of the three TCF7L2 polymorphisms with T2D by using the program admixmap to fit a logistic regression model incorporating individual ancestry, sex, age, body mass index and education. The markers rs12255372, rs7903146 and DG10S478 are in tight disequilibrium in the Mexican sample. We observed a significant association between the single-nucleotide polymorphism (SNP) rs12255372 and the microsatellite DG10S478 with T2D in the Mexican sample [rs12255372, odds ratio (OR) = 1.78, p = 0.017; DG10S478, OR = 1.62, p = 0.041]. The SNP rs7903146 shows similar trends, but its association with T2D is not as strong (OR = 1.39, p = 0.152). Analysis of the parental samples, as well as other available data, indicates that there are substantial population frequency differences for these polymorphisms: The frequencies of the T2D risk factors are more than 20% higher in European and West African populations than in East Asian and Native American populations.; A recent study found association of one microsatellite and five single nucleotide polymorphisms (SNPs) in intron 3 of the TCF7L2 gene with type 2 diabetes (T2D) in the Icelandic, Danish and American populations. The aim of the present study was to investigate if those SNPs were associated to T2D in two (family- and population-based) cohorts from northern Sweden. We genotyped four of the associated SNPs in a case-control cohort consisting of 872 T2D cases and 857 controls matched with respect to age, sex and geographical origin and in a sample of 59 extended families (148 affected and 83 unaffected individuals). Here, we report replication of association between T2D and three SNPs in the case-control (rs7901695, P=0.003; rs7901346, P=0.00002; and rs12255372, P=0.000004) and two SNPs in the family-based (rs7901695, P=0.01 and rs7901346, P=0.04) samples from northern Sweden. This replication strengthens the evidence for involvement of TCF7L2 in T2D.; Because mitochondria play pivotal roles in both insulin secretion from the pancreatic beta cells and insulin resistance of skeletal muscles, we performed a large-scale association study to identify mitochondrial haplogroups that may confer resistance against or susceptibility to type 2 diabetes mellitus (T2DM). The study population comprised 2,906 unrelated Japanese individuals, including 1,289 patients with T2DM and 1,617 controls, and 1,365 unrelated Korean individuals, including 732 patients with T2DM and 633 controls. The genotypes for 25 polymorphisms in the coding region of the mitochondrial genome were determined, and the haplotypes were classified into 10 major haplogroups (i.e., F, B, A, N9a, M7a, M7b, G, D4a, D4b, and D5). Multivariate logistic-regression analysis with adjustment for age and sex revealed that the mitochondrial haplogroup N9a was significantly associated with resistance against T2DM (P=.0002) with an odds ratio of 0.55 (95% confidence interval 0.40-0.75). Even in the modern environment, which is often characterized by satiety and physical inactivity, this haplogroup might confer resistance against T2DM.; Admixture mapping is a recently developed method for identifying genetic risk factors involved in complex traits or diseases showing prevalence differences between major continental groups. Type 2 diabetes (T2D) is at least twice as prevalent in Native American populations as in populations of European ancestry, so admixture mapping is well suited to study the genetic basis of this complex disease. We have characterized the admixture proportions in a sample of 286 unrelated T2D patients and 275 controls from Mexico City and we discuss the implications of the results for admixture mapping studies. Admixture proportions were estimated using 69 autosomal ancestry-informative markers (AIMs). Maternal and paternal contributions were estimated from geographically informative mtDNA and Y-specific polymorphisms. The average proportions of Native American, European and, West African admixture were estimated as 65, 30, and 5%, respectively. The contributions of Native American ancestors to maternal and paternal lineages were estimated as 90 and 40%, respectively. In a logistic model with higher educational status as dependent variable, the odds ratio for higher educational status associated with an increase from 0 to 1 in European admixture proportions was 9.4 (95%, credible interval 3.8-22.6). This association of socioeconomic status with individual admixture proportion shows that genetic stratification in this population is paralleled, and possibly maintained, by socioeconomic stratification. The effective number of generations back to unadmixed ancestors was 6.7 (95% CI 5.7-8.0), from which we can estimate that genome-wide admixture mapping will require typing about 1,400 evenly distributed AIMs to localize genes underlying disease risk between populations of European and Native American ancestry. Sample sizes of about 2,000 cases will be required to detect any locus that contributes an ancestry risk ratio of at least 1.5.; We recently described an association between risk of type 2diabetes and variants in the transcription factor 7-like 2 gene (TCF7L2; formerly TCF4), with a population attributable risk (PAR) of 17%-28% in three populations of European ancestry. Here, we refine the definition of the TCF7L2 type 2diabetes risk variant, HapB(T2D), to the ancestral T allele of a SNP, rs7903146, through replication in West African and Danish type 2 diabetes case-control studies and an expanded Icelandic study. We also identify another variant of the same gene, HapA, that shows evidence of positive selection in East Asian, European and West African populations. Notably, HapA shows a suggestive association with body mass index and altered concentrations of the hunger-satiety hormones ghrelin and leptin in males, indicating that the selective advantage of HapA may have been mediated through effects on energy metabolism.; These results suggest two diabetes susceptibility loci on chromosome 6q that may affect subsets of individuals with a milder form of T2DM.; In conclusion, our study suggests a potential role of the K121Q polymorphism or derived ENPP1 haplotypes in increased susceptibility to obesity and early impairment of glucose and insulin metabolism in children.; Research to date has identified several genes that are implicated in the etiology of ossification of the posterior longitudinal ligament of the spine (OPLL); however, their pathogenetic relevance remains obscure. The aim of this study is to identify susceptibility genes for OPLL through a large-scale case-control association study and to re-examine previously reported associations. A total of 109 single nucleotide polymorphisms (SNPs) in 35 candidate genes were genotyped for 711 sporadic OPLL patients and 896 controls. The differences in allelic and genotypic distribution between patients and controls were assessed using the chi (2) test with Bonferroni's correction. We also analyzed the association by separating patients into subgroups according to sex, age and the number of ossified vertebrae. The nominal P values fell below 0.05 for five SNPs in three genes. An intronic SNP in the TGF3 gene (P=0.00040) showed the most significant association. Previously reported associations of COL11A2, NPPS and TGFB1 with OPLL could not be reproduced. Further, no significant associations were detected in stratified analyses based on sex, age or the number of ossified vertebrae. TGFB3 warrants further investigation because it is located within a genomic region that has been positively linked with OPLL.; We have previously reported suggestive linkage of type 2 diabetes mellitus to chromosome 10q. We genotyped 228 microsatellite markers in Icelandic individuals with type 2 diabetes and controls throughout a 10.5-Mb interval on 10q. A microsatellite, DG10S478, within intron 3 of the transcription factor 7-like 2 gene (TCF7L2; formerly TCF4) was associated with type 2 diabetes (P = 2.1 x 10(-9)). This was replicated in a Danish cohort (P = 4.8 x 10(-3)) and in a US cohort (P = 3.3 x 10(-9)). Compared with non-carriers, heterozygous and homozygous carriers of the at-risk alleles (38% and 7% of the population, respectively) have relative risks of 1.45 and 2.41. This corresponds to a population attributable risk of 21%. The TCF7L2 gene product is a high mobility group box-containing transcription factor previously implicated in blood glucose homeostasis. It is thought to act through regulation of proglucagon gene expression in enteroendocrine cells via the Wnt signaling pathway.; We recently reported that the GG genotype of the interleukin-6 (IL-6)-174G>C promoter polymorphism is associated with clinical presentation of intracranial hemorrhage in brain arteriovenous malformation (AVM) patients. In this study, we investigated whether tissue IL-6 expression was associated with IL-6-174G>C genotype, and whether IL-6 was linked to downstream targets involved in angiogenesis and vascular instability. Our results showed that the highest IL-6 protein levels in brain AVM tissue were associated with IL-6-174GG genotype (GG: 57.7 +/- 20.2; GC: 35.6 +/- 26.6; CC: 13.9 +/- 10.2pg/mg; p = 0.001). IL-6 protein levels were increased in AVM tissue from patients with hemorrhagic presentation compared with patients without hemorrhage (55 +/- 22 vs 40 +/- 27pg/mg; p = 0.038). IL-6 messenger RNA expression strongly correlated with messenger RNA levels of IL-1beta, tumor necrosis factor-alpha, IL-8, matrix metalloproteinase-3 (MMP-3), MMP-9, and MMP-12. We further investigated the plausibility of IL-6 being an upstream cytokine responsible for initiating the angiogenic cascade by cell culture and animal experiments. IL-6 induced MMP-3 and MMP-9 expression and activity in mouse brain and increased proliferation and migration of cerebral endothelial cells. Together, our results suggest that the IL-6 genotype associated with intracranial hemorrhage modulates IL-6 expression in brain AVM tissue, which is consistent with the hypothesis that inflammatory processes induce angiogenic activity possibly contributory to brain AVM intracranial hemorrhage.; Mitochondria play an integral role in ATP production in cells and are involved in glucose metabolism and insulin secretion, suggesting that variants in the mitochondrial genome may contribute to diabetes susceptibility. In a study of Finnish families ascertained for type 2 diabetes mellitus (T2DM), we genotyped single nucleotide polymorphisms (SNPs) based on phylogenetic networks. These SNPs defined eight major haplogroups and subdivided groups H and U, which are common in Finns. We evaluated association with both diabetes disease status and up to 14 diabetes-related traits for 762 cases, 402 non-diabetic controls, and 465 offspring of genotyped females. Haplogroup J showed a trend toward association with T2DM affected status (OR 1.69, P=0.056) that became slightly more significant after excluding cases with affected fathers (OR 1.77, P=0.045). We also genotyped non-haplogroup-tagging SNPs previously reported to show evidence for association with diabetes or related traits. Our data support previous evidence for association of T16189C with reduced ponderal index at birth and also show evidence for association with reduced birthweight but not with diabetes status. Given the multiple tests performed and the significance levels obtained, this study suggests that mitochondrial genome variants may play at most a modest role in glucose metabolism in the Finnish population. Furthermore, our data do not support a reported maternal inheritance pattern of T2DM but instead show a strong effect of recall bias.; Inflammatory diseases frequently impair linear growth. Crohn's disease inhibits growth in up to one third of affected children. In rats with trinitrobenzenesulphonic acid-induced colitis, 40% of growth impairment is attributable to inflammation, with the rest being due to undernutrition. In transgenic mice without inflammation, raised IL-6 retards growth, suppressing insulin-like growth factor (IGF)-I. We hypothesized that IL-6, induced by intestinal inflammation, suppresses growth and inhibits IGF-I expression. Therefore, an anti-IL-6 Ab was given to rats with trinitrobenzene-sulphonic acid colitis. The Ab did not improve nutrient intake or decrease inflammation compared with untreated disease controls, but it significantly restored linear growth (P = 0.023) and increased IGF-I (P = 0.05). In humans, the IL-6 -174 G/C promoter polymorphism affects IL-6 transcription, with the GG genotype inducing the greatest IL-6 levels. Because IL-6 is increased in Crohn's disease, we further hypothesized that growth failure would vary with the IL-6 -174 genotype. At diagnosis, among 153 children with Crohn's disease, those with the IL-6 GG genotype were more growth-retarded than those with the GC or CC genotypes (height SD score, -0.51 vs. -0.10; P = 0.031). Also, the patients with the IL-6 GG genotype had higher circulating levels of C-reactive protein, an IL-6-induced product (36 vs. 18 mg/dl, P = 0.028). However, their risk of developing Crohn's disease was similar to other genotypes when compared with 351 healthy controls (P = 0.7). Thus, the IL-6 -174 genotype mediates growth failure in children with Crohn's disease.; Type 2 diabetes is a disorder of hyperglycemia resulting from failure of beta cells to produce adequate insulin to accommodate an increased metabolic demand. Here we show that regulation of mRNA translation through phosphorylation of eukaryotic initiation factor 2 (eIF2alpha) is essential to preserve the integrity of the endoplasmic reticulum (ER) and to increase insulin production to meet the demand imposed by a high-fat diet. Accumulation of unfolded proteins in the ER activates phosphorylation of eIF2alpha at Ser51 and inhibits translation. To elucidate the role of this pathway in beta-cell function we studied glucose homeostasis in Eif2s1(tm1Rjk) mutant mice, which have an alanine substitution at Ser51. Heterozygous (Eif2s1(+/tm1Rjk)) mice became obese and diabetic on a high-fat diet. Profound glucose intolerance resulted from reduced insulin secretion accompanied by abnormal distension of the ER lumen, defective trafficking of proinsulin, and a reduced number of insulin granules in beta cells. We propose that translational control couples insulin synthesis with folding capacity to maintain ER integrity and that this signal is essential to prevent diet-induced type 2 diabetes.; Persons with type 2 diabetes and persistent CSME have higher HbA1C at time of their disease than patients with resolved CSME. Patients with bilateral disease have more elevated HbA1C than those with unilateral disease.; A polymorphism in the inflammatory cytokine IL6, but not polymorphisms in angiogenesis-related genes, was associated with ICH presentation of BAVM. Further studies are needed to define the role of inflammatory cytokines in the pathogenesis of BAVM hemorrhage.; We conducted a genome-wide search for childhood obesity-associated traits, including BMI >/==" BORDER="0">95th percentile (PCT95), 97th percentile (PCT97), and 99th percentile (PCT99) as well as age of adiposity rebound (AAR), which corresponds to the beginning of the second rise in childhood adiposity. A set of 431 microsatellite markers was genotyped in 506 subjects from 115 multiplex French Caucasian families, with at least one child with a BMI >/==" BORDER="0">95th percentile. Among these 115 pedigrees, 97 had at least two sibs with a BMI >/==" BORDER="0">95th percentile. Fine-mapping was performed in the seven most positive loci. Nonparametric multipoint analyses revealed six regions of significant or suggestive linkage on chromosomes 2q33.2-q36.3, 6q22.31-q23.2, and 17p13 for PCT95, PCT97, or PCT99 and 15q12-q15.1, 16q22.1-q24.1, and 19p13.3-p13.11 for AAR. The strongest evidence of linkage was detected on chromosome 6q22.31 for PCT97 (maximum likelihood score: 4.06) at the marker D6S287. This logarithm of odds score meets genome-wide significance tested through simulation (empirical genome-wide P = 0.01 [0.0027-0.0254]). Six independent ge-nome scans in adults have reported quantitative trait loci on 6q linked to energy or glucose homeostasis-associated phenotypes. Possible candidate genes in this region include SIM1, MCHR2, and PC-1.; The human glycoprotein PC-1 codon Q121 allele has been correlated with insulin resistance, but not with type 2 diabetes or obesity. We investigated the prevalence of PC-1 Q121 in the Dominican Republic population (755 subjects studied) and whether this variant is associated with insulin resistance, obesity, or type 2 diabetes. The prevalence of PC-1 Q121 was high compared with that in other populations. The proportions of genotypes detected were: KK, 21.6%; KQ, 48.3%; and QQ, 30.1%. This compares to approximately 74%, 24%, and 2% in other populations. Among nonobese, nondiabetic subjects, the insulin response of KQ (P = 0.027) and QQ (P = 0.031) subjects was greater during the oral glucose tolerance test than that of KK subjects, whereas plasma glucose profiles were comparable. The Q allele was more prevalent in obese type 2 diabetics than in controls (P = 0.026; odds ratio = 1.56). Multiple regression analysis, after adjusting for age, gender, and body mass index, showed the QQ genotype to be associated with type 2 diabetes (P = 0.043; odds ratio = 2.74), but not obesity (P = 0.068). These results indicate that the PC-1 Q121 allele is exceptionally prevalent in the Dominican Republic, contributing to both insulin resistance and type 2 diabetes.; These data support the hypothesis that insulin resistance in the skeletal muscle of insulin-resistant offspring of patients with type 2 diabetes is associated with dysregulation of intramyocellular fatty acid metabolism, possibly because of an inherited defect in mitochondrial oxidative phosphorylation.; Neonatal diabetes mellitus can be transient or permanent. The severe form of permanent neonatal diabetes mellitus can be associated with pancreas agenesis. Normal pancreas development is controlled by a cascade of transcription factors, where insulin promoter factor 1 (IPF1) plays a crucial role. Here, we describe two novel mutations in the IPF1 gene leading to pancreas agenesis. Direct sequence analysis of exons 1 and 2 of the IPF1 gene revealed two point mutations within the homeobox in exon 2. Genetic analysis of the parents showed that each mutation was inherited from one parent. Mutations localized in helices 1 and 2, respectively, of the homeodomain, decreased the protein half-life significantly, leading to intracellular IPF1 levels of 36% and 27% of wild-type levels. Both mutant forms of IPF1 were normally translocated to the nucleus, and their DNA binding activity on different known target promoters was similar to that of the wild-type protein. However, transcriptional activity of both mutant IPF1 proteins, alone or in combination with HNF3 beta/Foxa2, Pbx1, or the heterodimer E47-beta 2 was reduced, findings accounted for by decreased IPF1 steady state levels and not by impaired protein-protein interactions. We conclude that the IPF1 level is critical for human pancreas formation.; Positional cloning is expected to identify novel susceptibility genes underlying complex traits, but replication of genome-wide linkage scan findings has proven erratic. To improve our ability to detect and prioritize chromosomal regions containing type 2 diabetes susceptibility genes, the GIFT consortium has implemented a meta-analysis of four scans conducted in European samples. These included the Botnia I and Botnia II scans, with respectively 58 and 353 pedigrees from Finland and Sweden, the Warren 2 scan performed in 573 multiplex sibships from the UK, and a scan of 143 families from France. The meta-analysis was implemented using the genome-search analysis method (GSMA), an exploratory data analysis technique which is robust across study designs. The analysis provided evidence for linkage of type 2 diabetes to six regions, with the strongest evidence on chromosome 17p11.2-q22 (P=0.0016), followed by 2p22.1-p13.2 (P=0.027), 1p13.1-q22 (P=0.028), 12q21.1-q24.12 (P=0.029), 6q21-q24.1 (P=0.033) and 16p12.3-q11.2 (P=0.033). Linkage analysis of the pooled raw genotype data generated maximum LOD scores in the same regions as identified by GSMA. Altogether, our results have indicated that GSMA is a valuable tool to identify chromosomal regions of interest and that accumulating evidence for linkage from small peaks detected across several samples may be more important than getting a high peak in a single sample. This meta-analysis has led to identification of a novel region on chromosome 17 linked to type 2 diabetes; this region has not been highlighted in any published scan to date but on the basis of these data justifies further exploration.; Many patients with type 2 diabetes fail to achieve or maintain the American Diabetes Association's recommended treatment goal of glycosylated hemoglobin levels. This multicenter, double-blind trial enrolled patients with type 2 diabetes who had inadequate glycemic control [glycosylated hemoglobin A(1C) (A1C), >7% and <12%) with diet and exercise alone to compare the benefits of initial therapy with glyburide/metformin tablets vs. metformin or glyburide monotherapy. Patients (n = 486) were randomized to receive glyburide/metformin tablets (1.25/250 mg), metformin (500 mg), or glyburide (2.5 mg). Changes in A1C, fasting plasma glucose, fructosamine, serum lipids, body weight, and 2-h postprandial glucose after a standardized meal were assessed after 16 wk of treatment. Glyburide/metformin tablets caused a superior mean reduction in A1C from baseline (-2.27%) vs. metformin (-1.53%) and glyburide (-1.90%) monotherapy (P = 0.0003). Glyburide/metformin also significantly reduced fasting plasma glucose and 2-h postprandial glucose values compared with either monotherapy. The final mean doses of glyburide/metformin (3.7/735 mg) were lower than those of metformin (1796 mg) and glyburide (7.6 mg). First-line treatment with glyburide/metformin tablets provided superior glycemic control over component monotherapy, allowing more patients to achieve American Diabetes Association treatment goals with lower component doses in drug-naive patients with type 2 diabetes.; The serum level of high-density lipoprotein cholesterol (HDL-c), which protects against the development of atherosclerosis, is under genetic control. However, the genetic components responsible for the serum HDL-c level are yet to be determined. A recent knockout mouse study demonstrated that hepatocyte nuclear factor-1 alpha (HNF-1 alpha) is an essential transcriptional regulator of HDL-c metabolism. In this study, the association of an HNF-1 alpha gene polymorphism, isoleucine (Ile) 27 leucine (Leu), with lipid parameters, in particular with serum HDL-c level, was studied in 356 unrelated Japanese men. Though no significant difference was observed in total cholesterol and triglyceride levels among the three genotypes, the serum HDL-c level was significantly associated with the genotype (P < 0.01, trend test). Subjects with the Ile/Ile genotype had low serum HDL-c levels, and those with the Leu/Leu genotype had high serum HDL-c levels. These results demonstrate that the HNF-1 alpha gene locus is associated with serum HDL-c level and suggest that the Ile27 allele is a risk marker for atherosclerosis.; The type 1 diabetes mellitus (T1DM) candidate gene SNP IL6-174G/C was genotyped in 253 Danish T1DM families (1129 individuals). TDT analysis demonstrated linkage in the presence of association between the IL6-174C allele and T1DM in the 416 T1DM offspring, P(tdt)=0.04. Gender conditioned TDT analyses revealed that linkage and association with T1DM were present in females exclusively; P(tdt)=6.5 x 10(-4) and P(tdt)=2.4 x 10(-4), respectively. Random transmission of the IL6-174C/G alleles was found in T1DM males, non-T1DM males and non-T1DM females; all P(tdt)>/=0.37. Heterogeneity analyses (T1DM versus non-T1DM females) excluded preferential meiotic segregation in females, P=4.6 x 10(-3), and demonstrated differences in the transmission patterns between female and male T1DM offspring, P=5.1 x 10(-3). The IL6-174 CC genotype was associated with younger age at onset of T1DM in females (P=0.002). The impact of 17beta-estradiol (E(2)) on the IL6-174G/C variants was investigated by reporter studies. The PMA stimulated activity of the T1DM risk IL6-174C variant exceeded that of the T1DM protective IL6-174G variant by approximately 70% in the absence of E(2) (P(c)=0.004), but not with E(2) present (P(c)=0.12). The PMA stimulated activity of the IL6-174G variant was repressed without E(2) present, but was derepressed by addition of E(2), P(c)=0.024. In contrast, the PMA stimulated IL6-174C activity was unaffected by E(2) as were the constitutive activities of the IL6-174G/C variants. In conclusion, higher IL6 promoter activity may confer risk to T1DM in very young females. This excess risk is negated with increasing age, possibly by the increasing E(2) levels in puberty.; Resistin, a recently discovered polypeptide, antagonizes insulin action and may play a part in the pathogenesis of insulin resistance. This study investigates whether resistin gene polymorphism can be associated with type 2 diabetes. We studied 1102 Chinese type 2 diabetes patients and 743 subjects without diabetes. The resistin 3'-untranslated region (UTR) +62G-->A polymorphism was determined by PCR. Type 2 diabetes subjects had a lower frequency of resistin gene 3'UTR +62A allele (GG:GA/AA, 83.5%:16.5%) than the controls (GG:GA/AA, 75.1%:24.9%; odds ratio, 1.524; 95% confidence interval, 1.268-1.831; P < 0.001). Unexpectedly, diabetic patients with the GG genotype had a higher prevalence of hypertension (GG:GA/AA, 49.8%:36.2%; odds ratio, 1.375; 95% confidence interval, 1.116-1.693; P = 0.001). Logistic regression analysis confirmed that the resistin gene 3'UTR +62G-->A polymorphism acts as an independent contributing factor to type 2 diabetes and hypertension. The mean systolic and diastolic blood pressure levels in diabetic subjects with the GG genotype (144 +/- 21/87 +/- 13 mm Hg) were significantly higher than those in subjects with GA/AA variants (139 +/- 21/84 +/- 14 mm Hg; P = 0.004 and P = 0.002, respectively). Multiple linear regression analysis showed resistin gene polymorphism to be an independent factor associated with systolic and diastolic blood pressures in type 2 diabetes patients. These findings suggest that resistin may play a role in the pathogenesis of type 2 diabetes and insulin resistance-related hypertension.; Obesity represents an expansion of adipose tissue (AT) mass and is closely related to insulin resistance and cardiovascular disease. Several hormonal signals have been shown to originate from AT, one of them being interleukin 6 (IL6), for which one third of circulating levels is accounted for by AT. To study the impact of the IL6 -174G/C polymorphism on obesity-related phenotypes, we genotyped a cohort of 270 French-Canadian men from the greater Quebec City area selected to cover a wide range of body fatness values. The IL6 -174G allele was more commonly observed among lean subjects (body mass index <25 kg/m(2), chi(2) = 7.27, P = 0.007 or waist-line <100 cm, chi(2) = 6.63, P = 0.01). When men were subdivided according to insulin and glucose levels at 180 min following the glucose load, using 160 pmol/l and 4.6 mmol/l, respectively, as cutoff points, the -174G allele was more frequently observed in groups with low concentrations of either insulin or glucose, P = 0.03 and P = 0.01, respectively. When comparisons between genotype groups were performed, -174G/G homozygotes presented the lowest waist circumference ( P < 0.05). In summary, this study showed that, in men, the IL6 -174G/C polymorphism is associated with some indices of body composition and parameters of glucose and insulin homeostasis.; IL-6 is a pleiotropic cytokine that plays a critical role in bone resorption. We describe two allelic variants in the IL-6 promoter, -572 and -174 G-->C, that alone and in combination influence IL-6 activity in vitro and in vivo. The association of IL-6 -572 genotypes and -572/-174 G-->C haplotypes with serum C-reactive protein (CRP), serum and urinary C-terminal cross-linking of type I collagen (a marker of bone resorption), and osteocalcin (a marker of bone formation) was investigated in a cohort of healthy postmenopausal women (n = 495; mean age +/- SD, 72 +/- 5.7 yr). Among IL-6 -572 genotypes, CRP was 37% higher (P = 0.02) and urinary C-terminal cross-linking of type I collagen was 20% higher (P = 0.01) in the presence of the C allele, whereas serum osteocalcin was not different. IL-6 -572/-174 haplotypes (G/C, G/G, and C/G) were significantly associated with all biochemical markers, and additive effects of the two polymorphic loci were found. Thus, there was a significant increase in the level of CRP (up to +79%; P = 0.007) and bone resorption markers (up to +32%; P = 0.017) with a decreasing number (from four to one) of IL-6 protective alleles -572G and -174C. In addition, there was a trend for lower age-adjusted bone mineral density at the lumbar spine in subjects with less IL-6 protective alleles (up to -9.6%; P = 0.037; P = 0.08 after further adjustment for weight). In conclusion, we describe two functional polymorphisms in the IL-6 gene regulatory region associated with IL-6 activity in postmenopausal women, both systemically (CRP) and locally in bone. As such, IL-6 polymorphisms are able to influence the risk of osteoporosis as well as other chronic disorders involving IL-6 activity.; Mutations in transcription factors expressed in the pancreatic beta-cell are a major cause of maturity-onset diabetes of the young (MODY). They have also been found in patients diagnosed with type 1 and type 2 diabetes mellitus, which may highlight the difficulty in diagnosing these forms of diabetes or perhaps indicate a direct role in the development of multiple forms of diabetes. We have screened the hepatocyte nuclear factor-1 beta (HNF-1 beta/MODY5) gene for mutations in a group of 126 unrelated Japanese patients with type 2 diabetes and a family history of at least one first degree relative with diabetes. We identified one patient with a nonsense mutation (R276X) and another with a missense mutation (S465R). These mutations were present in the heterozygous state and were not found in 132 nondiabetic subjects (264 normal alleles). We identified a second patient with the S465R mutation on screening a second group of 272 randomly selected type 2 diabetic patients but not in another 122 nondiabetic subjects. Functional studies indicated that R276X-HNF-1 beta was inactive and S465R-HNF-1 beta exhibited a 22% reduction in activity compared with the wild-type protein. The S465R mutation may function in a dominant-negative manner. The subject with the R276X mutation had MODY5 misdiagnosed as common type 2 diabetes. He was diagnosed with diabetes at 13 yr of age and also had small kidneys with multiple bilateral renal cysts and decreased urinary concentrating ability. The two subjects with the S465R mutation had typical late-onset type 2 diabetes and no evidence of kidney disease. We have identified two novel mutations in human HNF-1 beta gene. The prevalence of MODY5 among our population of Japanese diabetes patients with a strong positive family of disease is 0.8%. The S465R mutation was found in 0.5% of our patients with common type 2 diabetes and thus may be a rare genetic risk factor contributing to the development of type 2 diabetes rather than MODY5.; Variants in mitochondrial DNA (mtDNA) could be associated with type 2 diabetes because ATP plays a critical role in the production and release of insulin. Diabetes can be precipitated both by mtDNA mutations and by exposure to mitochondrial poisons. The risk of inheriting diabetes from an affected mother is greater than that from an affected father, but this is not explained by maternally inherited diabetes and/or deafness (MIDD) caused by the 3243G : C mtDNA point mutation, which accounts for less than 0.5% of cases of diabetes. A common mtDNA variant (the 16189 variant) is positively correlated with blood fasting insulin, but there are no definitive studies demonstrating that it is associated with diabetes. We demonstrated a significant association between the 16189 variant and type 2 diabetes in a population-based case-control study in Cambridgeshire, UK (n=932, odds ratio=1.61 (1.0-2.7, P=0.048), which was greatly magnified in individuals with a family history of diabetes from the father's side (odds ratio=infinity; P<0.001).; The genetic background that predisposes the Japanese population to type 2 diabetes is largely unknown. Therefore, we conducted a 10-cM genome-wide scan for type 2 diabetes traits in the 359 affected individuals from 159 families, yielding 224 affected sib-pairs of Japanese origin. Nonparametric multipoint linkage analyses performed in the whole population showed one suggestive linked region on 11p13-p12 (maximum logarithm of odds score [MLS] 3.08, near Pax6) and seven potentially linked regions (MLS >1.17) at 1p36-p32, 2q34, 3q26-q28, 6p23, 7p22-p21, 15q13-q21, and 20q12-q13 (near the gene for hepatocyte nuclear factor-4alpha [HNF-4alpha]). Subset analyses according to maximal BMI and early age at diagnosis added suggestive evidence of linkage with type 2 diabetes at 7p22-p21 (MLS 3.51), 15q13-q21 (MLS 3.91), and 20q12-q13 (MLS 2.32). These results support previous indication for linkage found on chromosome 3q, 15q, and 20q in other populations and identifies two new potential loci on 7p and 11p that may confer genetic risk for type 2 diabetes in the Japanese population.; To evaluate whether genetic variability at the IL-6 gene (IL-6) is associated with hyperandrogenism, we studied four common polymorphisms in the IL-6 promoter (-597G-->A, -572G--> C, -373A(n)T(n), -174G-->C) in 85 hyperandrogenic patients and 25 healthy women. We found 5 different haplotypes when considering the 3 biallelic polymorphisms at positions -597, -572, and -174 of IL-6 (relative frequencies in parentheses): GGG (0.505), AGC (0.377), GGC (0.059), GCG (0.055), and GCC (0.005). The frequencies of the GGG haplotype were 0.559 in patients and 0.320 in controls, whereas those of the AGC haplotype were 0.318 in patients and 0.580 in controls (chi(2) = 12.145; P < 0.02). The -597G-->A and -174G-->C polymorphisms were in linkage disequilibrium (chi(2) = 152.220; P < 0.00001), and were associated with patient or control status. -597G and -174G alleles were more frequent in patients in homozygosity or considering subjects homozygous and heterozygous for G alleles as a whole (P < 0.05 for all analyses). In healthy women G alleles at -597 and -174 were associated with statistically significant higher circulating levels of IL-6 and basal cortisol, 11-deoxycortisol, and 17-hydroxyprogesterone and a tendency (P < 0.10) for higher total T concentrations compared with -597A and -174C alleles. On the contrary, neither the -572G-->C nor the -373A(n)T(n) polymorphism was related to hyperandrogenism or influenced any clinical or biochemical variable. In conclusion, our present results suggest that the -597G-->A and -174G-->C polymorphisms in IL-6 are involved in the pathogenesis of hyperandrogenic disorders.; Ossification of the posterior longitudinal ligament (OPLL) of the spine is a disease that causes paralysis by compressing the spinal cord. Based on the fact that the nucleotide pyrophosphatase (Npps) gene is responsible for ectopic ossification in ttw, an OPLL model mouse, the possibility was explored whether the human NPPS gene is associated with susceptibility to and severity of OPLL. First, we screened for single-nucleotide polymorphisms (SNPs) in the human NPPS locus using selected 25 OPLL patients with young onset (< 35 years old) or severe ossification (> 10 ossified vertebrae), and identified three novel SNPs in the locus. A case-control association study between 180 OPLL patients and 265 non-OPLL controls showed that one of these SNPs, IVS15-14T --> C substitution, was more frequently observed in OPLL patients (p = 0.022), especially in those with severe ossification (p < 0.0001) and young onset (p = 0.002), than in controls. A stratified study with the number of ossified vertebrae in OPLL patients revealed that IVS15-14T --> C substitution (p = 0.013) as well as young onset (p = 0.046) and female sex (p = 0.006) were associated with severe ossification. We conclude that the IVS15-14T --> C substitution in the human NPPS gene is associated not only with susceptibility to, but also with severity of OPLL.; We report a total of 23 novel mutations of the SLC2A2 ( GLUT2) gene in 49 patients with a clinical diagnosis of Fanconi-Bickel syndrome (FBS). Molecular genetic analysis has now been performed in more than 50% of the 109 FBS cases from 88 families that we have been able to locate world-wide since the original report in 1949. In these 49 patients, 33 different SLC2A2 mutations (9 missense, 7 nonsense, 10 frameshift, 7 splice-site) have been detected. Thus, our results confirm that mutations of SLC2A2 are the basic defect in patients with FBS. Mutations of SLC2A2 were detected in historical FBS patients in whom some of the characteristic clinical features (hepatorenal glycogen accumulation, glucose and galactose intolerance, fasting hypoglycemia, a characteristic tubular nephropathy) and the effect of therapy were described for the first time. Mutations were also found in patients with atypical clinical signs such as intestinal malabsorption, failure to thrive, the absence of hepatomegaly, or renal hyperfiltration. No single prevalent SLC2A2 mutation was responsible for a significant number of cases. In a high percentage (74%) of FBS patients, the mutation is homozygous, so we conclude that the prevalence of SLC2A2 mutations is relatively low in most populations. No mutational hot spots within SLC2A2 or even within homologous sequences among the genes for facilitative glucose transporters were detected.; Disruption of the insulin receptor substrate-2 was shown to cause type 2 diabetes in mice. This could be largely attributed to abnormal beta-cell development. In humans, a prevalent polymorphism in insulin receptor substrate-2 (Gly1057Asp) was not found be associated with type 2 diabetes in linkage and association studies. We tested the hypothesis that an extreme challenge of the beta cell might reveal subtle abnormalities in carriers of this polymorphism undetected by conventional insulin secretion tests. Therefore, in addition to assessing beta-cell function by oral glucose tolerance testing (n = 318, normal glucose tolerance), we measured the secretory response to maximal stimulation by hyperglycemia (10 mM), glucagon-like peptide-1, and arginine administered in an additive fashion (n = 77, nondiabetic). The allelic frequency of the Asp allele was approximately 37%. Neither the beta-cell function indices from the oral glucose tolerance test nor the secretory response during the hyperglycemic clamp differed measurably between carriers and controls. Moreover, maximal plasma C-peptide concentrations in response to the combined glucose, glucagon-like peptide-1, and arginine stimulus was not different between Gly/Gly (10,745 +/- 1,186 pmol/liter) and X/Asp (10,800 +/- 490 pmol/liter, P = 0.99). In conclusion, our findings strongly suggest that the Gly1057Asp polymorphism in insulin receptor substrate-2 is not associated with beta-cell dysfunction. The normal maximal insulin secretory response makes it unlikely that this common polymorphism results in abnormal beta-cell development.; NA; We investigated the significance of the variants of the IRS-2 gene in patients with type 2 diabetes. The entire coding part of the IRS-2 gene was screened by single-strand conformation polymorphism analysis in 40 Chinese and 40 Finnish patients with late-onset type 2 diabetes. The association of the variants of the IRS-2 gene with type 2 diabetes was studied in 85 Finnish diabetic patients and 82 Finnish control subjects and in 100 Chinese diabetic patients and 85 Chinese control subjects. The four variants predicting structural changes in the insulin receptor substrate (IRS)-2 protein included an insertion of AAC (Asn) in the Asn repeat sequence centered around codons 29-36 (allele frequencies of 0 vs. 0.6% and 1.5 vs. 0%), the Ala157Thr substitution (0 vs. 0% and 0.5 vs. 0%), the Leu647Val substitution (0.6 vs. 0% and 0 vs. 0%), and the Gly1057Asp polymorphism (31 vs. 31% and 35 vs. 30%) (P = NS for all comparisons). Furthermore, six silent variants were observed (CGC147CGG, CCC155CCG, GCC156GCT, AGT723AGC, TGT816TGC, and CCC829CCT). The Gly1057Asp polymorphism was not associated with insulin resistance or impaired insulin secretion in Finnish subjects with normal glucose tolerance (n = 295) or impaired glucose tolerance (n = 38). These data indicate that structural variants of the IRS-2 gene were uncommon in Finnish and Chinese patients with type 2 diabetes. Thus, the variants in the coding part of the IRS-2 gene are unlikely to have a major role in the development of type 2 diabetes in Finnish or Chinese subjects.; It has been shown recently that troglitazone exerts an anti-inflammatory effect, in vitro, and in experimental animals. To test these properties in humans, we investigated the effect of troglitazone on the proinflammatory transcription factor nuclear factor-kappaB and its inhibitory protein IkappaB in mononuclear cells (MNC) and plasma soluble intracellular adhesion molecule-1, monocyte chemoattractant protein-1, plasminogen activator inhibitor-1, and C-reactive protein. We also examined the effect of troglitazone on reactive oxygen species generation, p47(phox) subunit expression, 9-hydroxyoctadecadienoic acid (9-HODE), 13-HODE, o-tyrosine, and m-tyrosine in obese patients with type 2 diabetes. Seven obese patients with type 2 diabetes were treated with troglitazone (400 mg/day) for 4 weeks. Blood samples were obtained at weekly intervals. Nuclear factor-kappaB binding activity in MNC nuclear extracts was significantly inhibited after troglitazone treatment at week 1 and continued to be inhibited up to week 4. On the other hand, IkappaB protein levels increased significantly after troglitazone treatment at week 1, and this increase persisted throughout the study. Plasma monocyte chemoattractant protein-1 and soluble intracellular adhesion molecule-1 concentrations did not decrease significantly after troglitazone treatment, although there was a trend toward inhibition. Reactive oxygen species generation by polymorphonuclear cells and MNC, p47(phox) subunit protein quantities, plasminogen activator inhibitor-1, and C-reactive protein levels decreased significantly after troglitazone intake. 13-HODE/linoleic acid and 9-HODE/linoleic acid ratios also decreased after troglitazone intake. However, o-tyrosine/phenylalanine and m-tyrosine/phenylalanine ratios did not change significantly. These data show that troglitazone has profound antiinflammatory effects in addition to antioxidant effects in obese type 2 diabetics; these effects may be relevant to the recently described beneficial antiatherosclerotic effects of troglitazone at the vascular level.; We assessed the prevalence of families with both type 1 and type 2 diabetes in Finland; and we studied, in patients with type 2 diabetes, the association between a family history of type 1 diabetes, glutamic acid decarboxylase (GAD) antibodies (GADab), and type 1 diabetes-associated human leukocyte antigen (HLA) DQB1-genotypes. Further, in mixed type 1/type 2 diabetes families, we investigated whether sharing an HLA haplotype with a family member with type 1 diabetes influenced the manifestation of type 2 diabetes. Among 695 families ascertained through the presence of more than 1 patient with type 2 diabetes, 100 (14%) also had members with type 1 diabetes. Type 2 diabetic patients from the mixed families had, more often, GADab (18% vs. 8%, P < 0.0001) and DQB1*0302/X genotype (25% vs. 12%, P = 0.005) than patients from families with only type 2 diabetes; but they had a lower frequency of DQB1*02/0302 genotype, compared with adult-onset type 1 patients (4% vs. 27%, P < 0.0001). In the mixed families, the insulin response to oral glucose load was impaired in patients who had HLA class II risk haplotypes, either DR3(17)-DQA1*0501-DQB1*02 or DR4*0401/4-DQA1*0301-DQB1*0302, compared with patients without such haplotypes (P = 0.016). This finding was independent of the presence of GADab. We conclude that type 1 and type 2 diabetes cluster in the same families. A shared genetic background with a patient with type 1 diabetes predisposes type 2 diabetic patients both to autoantibody positivity and, irrespective of antibody positivity, to impaired insulin secretion. The findings support a possible genetic interaction between type 1 and type 2 diabetes mediated by the HLA locus.; Type 2 diabetes mellitus is a complex phenotype that is frequently associated with central obesity and insulin resistance. Recently, a protein named resistin, encoded by RSTN (OMIM #605565), was identified in adipose tissue. Serum resistin was elevated in obese and diabetic mice, and administration of resistin to normal mice was found to interfere with glucose tolerance and insulin action. Because of these functions, resistin is a candidate gene for diabetes and obesity. Through the use of DNA sequencing, we thus developed amplification primers for rapid screening of the RSTN gene that encodes resistin. No putative mutations were found, but two noncoding single-nucleotide polymorphisms (SNPs) were identified, and these were found to vary in frequency across various ethnic groups. The identification of amplification primers and SNPs provides tools to investigate resistin for association with other phenotypes.; Fibroblast growth factor (FGF) signalling has been implicated in patterning, proliferation and cell differentiation in many organs, including the developing pancreas. Here we show that the FGF receptors (FGFRs) 1 and 2, together with the ligands FGF1, FGF2, FGF4, FGF5, FGF7 and FGF10, are expressed in adult mouse beta-cells, indicating that FGF signalling may have a role in differentiated beta-cells. When we perturbed signalling by expressing dominant-negative forms of the receptors, FGFR1c and FGFR2b, in the pancreas, we found that that mice with attenuated FGFR1c signalling, but not those with reduced FGFR2b signalling, develop diabetes with age and exhibit a decreased number of beta-cells, impaired expression of glucose transporter 2 and increased proinsulin content in beta-cells owing to impaired expression of prohormone convertases 1/3 and 2. These defects are all characteristic of patients with type-2 diabetes. Mutations in the homeobox gene Ipf1/Pdx1 are linked to diabetes in both mouse and human. We also show that Ipf1/Pdx1 is required for the expression of FGFR1 signalling components in beta-cells, indicating that Ipf1/Pdx1 acts upstream of FGFR1 signalling in beta-cells to maintain proper glucose sensing, insulin processing and glucose homeostasis.; Despite recent advances in the molecular genetics of type 2 diabetes, the majority of susceptibility genes in humans remain to be identified. We therefore conducted a 10-cM genomewide search (401 microsatellite markers) for type 2 diabetes-related traits in 637 members of 143 French pedigrees ascertained through multiple diabetic siblings, to map such genes in the white population. Nonparametric two-point and multipoint linkage analyzes-using the MAPMAKER-SIBS (MLS) and MAXIMUM-BINOMIAL-LIKELIHOOD (MLB) programs for autosomal markers and the ASPEX program for chromosome X markers-were performed with six diabetic phenotypes: diabetes and diabetes or glucose intolerance (GI), as well as with each of the two phenotypes associated with normal body weight (body-mass index<27 kg/m(2)) or early age at diagnosis (<45 years). In a second step, high-resolution genetic mapping ( approximately 2 cM) was performed in regions on chromosomes 1 and 3 loci showing the strongest linkage to diabetic traits. We found evidence for linkage with diabetes or GI diagnosed at age <45 years in 92 affected sib pairs from 55 families at the D3S1580 locus on chromosome 3q27-qter using MAPMAKER-SIBS (MLS = 4.67, P=.000004), supported by the MLB statistic (MLB-LOD=3.43, P=.00003). We also found suggestive linkage between the lean diabetic status and markers APOA2-D1S484 (MLS = 3. 04, P=.00018; MLB-LOD=2.99, P=.00010) on chromosome 1q21-q24. Several other chromosomal regions showed indication of linkage with diabetic traits, including markers on chromosome 2p21-p16, 10q26, 20p, and 20q. These results (a) showed evidence for a novel susceptibility locus for type 2 diabetes in French whites on chromosome 3q27-qter and (b) confirmed the previously reported diabetes-susceptibility locus on chromosome 1q21-q24. Saturation on both chromosomes narrowed the regions of interest down to an interval of <7 cM.; Type 2 diabetes mellitus is a complex disorder encompassing multiple metabolic defects. We report results from an autosomal genome scan for type 2 diabetes-related quantitative traits in 580 Finnish families ascertained for an affected sibling pair and analyzed by the variance components-based quantitative-trait locus (QTL) linkage approach. We analyzed diabetic and nondiabetic subjects separately, because of the possible impact of disease on the traits of interest. In diabetic individuals, our strongest results were observed on chromosomes 3 (fasting C-peptide/glucose: maximum LOD score [MLS] = 3.13 at 53.0 cM) and 13 (body-mass index: MLS = 3.28 at 5.0 cM). In nondiabetic individuals, the strongest results were observed on chromosomes 10 (acute insulin response: MLS = 3.11 at 21.0 cM), 13 (2-h insulin: MLS = 2.86 at 65.5 cM), and 17 (fasting insulin/glucose ratio: MLS = 3.20 at 9.0 cM). In several cases, there was evidence for overlapping signals between diabetic and nondiabetic individuals; therefore we performed joint analyses. In these joint analyses, we observed strong signals for chromosomes 3 (body-mass index: MLS = 3.43 at 59.5 cM), 17 (empirical insulin-resistance index: MLS = 3.61 at 0.0 cM), and 19 (empirical insulin-resistance index: MLS = 2.80 at 74.5 cM). Integrating genome-scan results from the companion article by Ghosh et al., we identify several regions that may harbor susceptibility genes for type 2 diabetes in the Finnish population.; We performed a genome scan at an average resolution of 8 cM in 719 Finnish sib pairs with type 2 diabetes. Our strongest results are for chromosome 20, where we observe a weighted maximum LOD score (MLS) of 2.15 at map position 69.5 cM from pter and secondary weighted LOD-score peaks of 2.04 at 56.5 cM and 1.99 at 17.5 cM. Our next largest MLS is for chromosome 11 (MLS = 1.75 at 84.0 cM), followed by chromosomes 2 (MLS = 0.87 at 5.5 cM), 10 (MLS = 0.77 at 75.0 cM), and 6 (MLS = 0.61 at 112.5 cM), all under an additive model. When we condition on chromosome 2 at 8.5 cM, the MLS for chromosome 20 increases to 5.50 at 69.0 cM (P=.0014). An ordered-subsets analysis based on families with high or low diabetes-related quantitative traits yielded results that support the possible existence of disease-predisposing genes on chromosomes 6 and 10. Genomewide linkage-disequilibrium analysis using microsatellite marker data revealed strong evidence of association for D22S423 (P=.00007). Further analyses are being carried out to confirm and to refine the location of these putative diabetes-predisposing genes.; Kaposi sarcoma (KS) is an angioproliferative inflammatory condition that occurs commonly in patients infected with human immunodeficiency virus (HIV). Inflammatory cytokines and growth factors promote the development of KS. Because physiologically important cytokine polymorphisms modulate host inflammatory responses, we investigated the association between KS and common regulatory polymorphisms in 5 proinflammatory cytokine genes encoding interleukin (IL) IL-1alpha, IL-1beta, tumor necrosis factor (TNF) alpha, TNF-beta, and IL-6 and in the IL-1 receptor antagonist (IL1RN). We also examined the contribution of stromal-derived factor 1 and chemokine receptor 5 (Delta32) polymorphisms to KS development. The population consisted of 115 HIV-infected men with KS and 126 deceased HIV-infected men without KS. The only strong association was observed between an IL6 promoter polymorphism (G-174C) and susceptibility to KS in HIV-infected men (P =.0035). Homozygotes for IL6 allele G, associated with increased IL6 production, were overrepresented among patients with KS (P =.0046), whereas allele C homozygotes were underrepresented (P =.0062). Substantial in vitro evidence indicates that IL-6 contributes to the pathogenesis of KS. Our results show that IL6 promoter genotypes associated with altered gene expression are risk factors for development of KS. Identification of a genetic risk factor for development of KS has important clinical implications for prevention and therapy.; Genetic association studies are viewed as problematic and plagued by irreproducibility. Many associations have been reported for type 2 diabetes, but none have been confirmed in multiple samples and with comprehensive controls. We evaluated 16 published genetic associations to type 2 diabetes and related sub-phenotypes using a family-based design to control for population stratification, and replication samples to increase power. We were able to confirm only one association, that of the common Pro12Ala polymorphism in peroxisome proliferator-activated receptor-gamma(PPARgamma) with type 2 diabetes. By analysing over 3,000 individuals, we found a modest (1.25-fold) but significant (P=0.002) increase in diabetes risk associated with the more common proline allele (85% frequency). Moreover, our results resolve a controversy about common variation in PPARgamma. An initial study found a threefold effect, but four of five subsequent publications failed to confirm the association. All six studies are consistent with the odds ratio we describe. The data implicate inherited variation in PPARgamma in the pathogenesis of type 2 diabetes. Because the risk allele occurs at such high frequency, its modest effect translates into a large population attributable risk-influencing as much as 25% of type 2 diabetes in the general population.; Genetic analysis of the diabetic GK rat has revealed several diabetes susceptibility loci. Congenic strains have been established for the major diabetes locus, Niddm1, by transfer of GK alleles onto the genome of the normoglycemic F344 rat. Niddm1 was dissected into two subloci, physically separated in the congenic strains Niddm1b and Niddm1i, each with at least one disease susceptibility gene. Here we have mapped Niddm1b to 1 cM by genetic and pathophysiological characterization of new congenic substrains for the locus. The gene encoding insulin-degrading enzyme (IDE:) was located to this 1 cM region, and the two amino acid substitutions (H18R and A890V) identified in the GK allele reduced insulin-degrading activity by 31% in transfected cells. However, when the H18R and A890V variants were studied separately, no effects were observed, demonstrating a synergistic effect of the two variants on insulin degradation. No effect on insulin degradation was observed in cell lysates, indicating that the effect is coupled to receptor-mediated internalization of insulin. Congenic rats with the IDE: GK allele displayed post-prandial hyperglycemia, reduced lipogenesis in fat cells, blunted insulin-stimulated glucose transmembrane uptake and reduced insulin degradation in isolated muscle. Analysis of additional rat strains demonstrated that the dysfunctional IDE: allele was unique to GK. These data point to an important role for IDE: in the diabetic phenotype in GK.; In this study, we have compared resistance to insulin-mediated glucose disposal and plasma concentrations of nitric oxide (NO) and cyclic-GMP in healthy volunteers with (n = 35) or without (n = 27) at least one sibling and one parent with type 2 diabetes. The 62 volunteers were further divided into groups of those with normal glucose tolerance or impaired glucose tolerance. Insulin-mediated glucose disposal was quantified by determining the insulin sensitivity index (ISI) in response to a low-dose, constant infusion of insulin (25 mU/kg x h) and glucose (4 mg/kg x min) for 150 min. The mean (+/-SEM) ISI [(mL kg(-1) min(-1)/pmol/L) x 10(3)] was significantly greater in those without a family history (30.3 +/- 2.3) as compared with nondiabetic volunteers with a family history of type 2 diabetes, whether they had normal glucose tolerance (17.0 +/- 7.2) or impaired glucose tolerance (9.5 +/- 1.4). In addition, basal NO levels, evaluated by the measurement of its stable end products [i.e. nitrite and nitrate levels (NO2-/ NO3-)], were significantly higher, and cyclic-GMP levels, its effector messenger, were significantly lower in those with a family history, irrespective of their degree of glucose tolerance, when compared with healthy volunteers without a family history of type 2 diabetes. Furthermore, when the 62 volunteers were analyzed as one group, there was a negative correlation between ISI and NO2-/NO3- levels (r = -0.35; P < 0.005) and a positive correlation between ISI and cyclic-GMP levels (r = 0.30; P < 0.02). These results have shown that alterations of the NO/cyclic-GMP pathway seem to be an early event in nondiabetic individuals with a family history of type 2 diabetes and these changes are correlated with the degree of insulin resistance.; Among the Oji-Cree of northern Ontario, we previously identified a novel variant in the HNF1A gene, namely G319S, that was strongly associated with type 2 diabetes. However, the majority of subjects with diabetes did not have the HNF1A S319 variant, suggesting that there might be other genetic determinants of diabetes susceptibility. In the course of sequencing candidate genes in diabetic subjects who were homozygous for HNF1A G319/G319, we found that some of them had the PPARG A12 variant. After genotyping PPARG in the entire adult Oji-Cree population, we found that: 1) PPARG A12 was strongly associated with type 2 diabetes in women, but not men; 2) among women, the odds of being affected for carriers of PPARG A12 compared with noncarriers was 2.3 (95% confidence interval, 1.4-3.8); and 3) among women, affected carriers of PPARG A12 had a significantly earlier age-of-onset and/or age-at-diagnosis compared with noncarriers. When taken together with the previously reported association of diabetes with HNF1A in both men and women, the gender-specific association with PPARG A12 confirms that type 2 diabetes is etiologically complex in the Oji-Cree and that at least two genes are involved in determining susceptibility to the disease in these people.; Type 2 diabetes is a polygenic and genetically heterogeneous disease . The age of onset of the disease is usually late and environmental factors may be required to induce the complete diabetic phenotype. Susceptibility genes for diabetes have not yet been identified. Islet-brain-1 (IB1, encoded by MAPK8IP1), a novel DNA-binding transactivator of the glucose transporter GLUT2 (encoded by SLC2A2), is the homologue of the c-Jun amino-terminal kinase-interacting protein-1 (JIP-1; refs 2-5). We evaluated the role of IBi in beta-cells by expression of a MAPK8IP1 antisense RNA in a stable insulinoma beta-cell line. A 38% decrease in IB1 protein content resulted in a 49% and a 41% reduction in SLC2A2 and INS (encoding insulin) mRNA expression, respectively. In addition, we detected MAPK8IP1 transcripts and IBi protein in human pancreatic islets. These data establish MAPK8IP1 as a candidate gene for human diabetes. Sibpair analyses performed on i49 multiplex French families with type 2 diabetes excluded MAPK8IP1 as a major diabetogenic locus. We did, however, identify in one family a missense mutation located in the coding region of MAPK8IP1 (559N) that segregated with diabetes. In vitro, this mutation was associated with an inability of IB1 to prevent apoptosis induced by MAPK/ERK kinase kinase 1 (MEKK1) and a reduced ability to counteract the inhibitory action of the activated c-JUN amino-terminal kinase (JNK) pathway on INS transcriptional activity. Identification of this novel non-maturity onset diabetes of the young (MODY) form of diabetes demonstrates that IB1 is a key regulator of 3-cell function.; Several lines of evidence indicate that interleukin-6 (IL-6) is involved not only in the hepatic acute phase response but also in adipose tissue metabolism, lipoprotein lipase activity, and hepatic triglyceride secretion. A polymorphism in the IL-6 gene, associated with differences in IL-6 transcription rate, has been recently described. We aimed to study whether this IL-6 gene polymorphism leads to differences in fasting and postglucose load plasma lipids in healthy subjects. Subjects with G at position -174 of the IL-6 gene were similar in age, sex, body mass index, and waist to hip ratio in comparison with carriers of the C allele. However, G carriers showed almost twice plasma triglycerides (1.5 +/- 0.9 vs. 0.90 +/- 0.37 mmol/L; P = 0.01), very low-density lipoprotein (VLDL)-triglycerides (0.97 +/- 0.69 vs. 0.42 +/- 0.2 mmol/L; P = 0.002), higher fasting (881 vs. 458 micromol/L; P = 0.01), and postglucose load free fatty acids (299 vs. 90.5 micromol/L; P = 0.03), slightly lower high-density lipoprotein-2 cholesterol (0.25 +/- 0.14 vs. 0.39 +/- 0.26 mmol/L; P = 0.058), and similar cholesterol and LDL-cholesterol levels than carriers of the C allele. Serum IL-6 levels correlated positively with fasting triglycerides, VLDL-triglycerides, and postload free fatty acids (r = 0.61, 0.65 and 0.60, respectively; P < 0.001) and negatively with high-density lipoprotein-cholesterol (r = -0.42, P < 0.05). A tendency toward higher serum IL-6 levels was observed among G carriers (9.9 +/- 6.9 vs. 6.85 +/- 1.7 pg/mL; P = 0.09). The -174G construct was recently reported to show higher expression of IL-6 in He La cells and was associated with higher plasma IL-6 levels than the -174C allele. Thus, the results of the present study suggest that subjects with the G allele, associated to higher IL-6 secretion, are prone to lipid abnormalities. Whether this polymorphism contributes to lipid alterations associated with other metabolic disorders awaits additional studies.; No genetic variability was found in the IRS-2 promoter. A rare IRS-2 variant at codon 647 has been identified in Type II diabetic patients. The prevalent codon 1057 polymorphism had no consistent effect on insulin secretion or insulin sensitivity. [Diabetologia (1999) 42: 1244-1249]; OPLL (ossification of the posterior longitudinal ligament of the spine) is a common form of human myelopathy with a prevalence of as much as 4% in a variety of ethnic groups. To clarify the genetic factors that predispose to OPLL, we have studied ttw (tiptoe walking), a mouse model that presents ectopic ossification of the spinal ligaments similar to OPLL and have found that the ttw phenotype is caused by the nonsense mutation of the gene encoding nucleotide pyrophosphatase (NPPS), a membrane-bound glycoprotein thought to produce inorganic pyrophosphate, a major inhibitor of calcification and mineralization. To investigate a possible role of NPPS in the etiology of OPLL, we have examined its genetic variations in OPLL patients. A total of 323 OPLL patients was screened by means of polymerase chain reaction/single-strand conformation polymorphism analysis covering all the exons and their surrounding introns, plus about 1.5-kb of the promoter region. We identified ten nucleotide variations in the NPPS gene; five of the alterations caused amino-acid substitutions, and two of them were found specifically in OPLL patients. Subsequently, we performed an association study using these variations and found a significant association of an allele, viz., a deletion of T at a position 11 nucleotides upstream from the splice acceptor site of intron 20 (IVS20-11delT), with OPLL; the proportion of the individuals having this deletion was significantly higher (P = 0.0029) in OPLL patients than in controls, indicating that those who have this variation may be more susceptible to the abnormal ossification of the spinal ligaments. Thus, our study suggests that NPPS plays an important role in the etiology of human OPLL.; Considerable evidence supports a major inherited component of type 2 diabetes. We initially conducted a genome-wide scan with 440 microsatellite markers at 10-cM intervals in 19 multigenerational families of Northern European ancestry with at least two diabetic siblings. Initial two-point analyses of these families directed marker typing of 23 additional families. Subsequently, all available marker data on the total of 42 families were analyzed using both parametric and nonparametric multipoint methods to test for linkage to type 2 diabetes. One locus on chromosome 1q21-1q23 met genome-wide criteria for significant linkage under a model of recessive inheritance with a common diabetes allele (logarithm of odds [LOD] = 4.295). Both pedigree-based nonparametric linkage (NPL) analysis and affected sib pair (MAPMAKER/SIBS) nonparametric methods also showed the highest genome-wide scores at this region, near markers CRP and APOA2, but failed to meet levels of genome-wide significance. The risk of type 2 diabetes to siblings of a diabetic person when compared with the population (lambdaS) was estimated from MAPMAKER/SIBS to be 2.8 in these 42 families. Simulation studies using study data confirmed a genome-wide significance level of P<0.05 (95% CI 0.005-0.0466). However, analysis of 20 similarly ascertained but smaller families failed to confirm this linkage. The LOD score with 50% heterogeneity for all 62 families considered together was only 2.25, with an estimated lambdaS of 1.87. Our data suggest a novel diabetes susceptibility locus near APOA2 on chromosome 1 in a region with many transcribed genes.; Both defective insulin secretion and insulin resistance have been reported in relatives of type 2 diabetic subjects. We tested 120 members of 26 families with a type 2 diabetic sibling pair with a tolbutamide-modified, frequently sampled i.v. glucose tolerance test to determine the insulin sensitivity index (S(I)) and acute insulin response to glucose (AIRglucose). A measure of beta-cell compensation for insulin sensitivity was calculated as the product S(I) x AIRglucose, based on the demonstrated hyperbolic relationship between insulin sensitivity and insulin secretion. A percentile score for this compensation was assigned based on published values. Of the 120 family members, 26 had previously diagnosed impaired glucose tolerance on oral testing, and 94 had normal glucose tolerance tests. As a group, family members showed a significantly lower S(I) x AIRglucose than a similar, previously reported, control population, even when impaired glucose tolerance members were excluded. We performed a multivariate analysis of diabetes status, S(I), AIRglucose and to estimate the heritability of each trait and the genetic and environmental correlations between traits. We estimated the heritability of S(I) x AIRglucose to be 67 +/- 3% when all members were included and 70 +/- 4% when only normal glucose tolerance members were considered. Both AIRglucose and S(I) were also familial, albeit with lower heritabilities (38 +/- 1% and 38 +/- 2%, respectively, for all family members). Both S(I) x AIRglucose and S(I) showed strong negative genetic correlations with diabetes (-85 +/- 3% and -87 +/- 2%, respectively, all family members), whereas AIRglucose did not correlate with diabetes. We conclude that insulin secretion, as measured by S(I) x AIRglucose, is decreased in nondiabetic members of familial type 2 diabetic kindreds, that S(I) x AIRglucose in these high risk families is highly heritable, and that the same polygenes may determine diabetes status and a low S(I) x AIRglucose. Our data suggest that insulin secretion, when expressed as an index normalized for insulin sensitivity, is more familial than either insulin sensitivity or first phase insulin secretion alone and may be a very useful trait for identifying genetic predisposition to type 2 diabetes.; The aim of the study was 1) to establish the prevalence of GAD antibodies (GADab) in a population-based study of type 2 diabetes in western Finland, 2) to genetically and phenotypically characterize this subgroup, and 3) to provide a definition for latent autoimmune diabetes in adults (LADA). The prevalence of GADab was 9.3% among 1,122 type 2 diabetic patients, 3.6% among 558 impaired glucose tolerance (IGT) subjects, and 4.4% among 383 nondiabetic control subjects. Islet antigen 2 antibodies (IA2ab) or islet cell antibodies were detected in only 0.5% of the GADab- patients. The GADab+ patients had lower fasting C-peptide concentrations (median [interquartile range]: 0.46 [0.45] vs. 0.62 [0.44] nmol/l, P = 0.0002) and lower insulin response to oral glucose compared with GADab- patients. With respect to features of the metabolic syndrome, the GADab+ patients had lower systolic (140 [29.1] vs. 148 [26.0] mmHg, P = 0.009) and diastolic (79.2 [17.6] vs. 81.0 [13.1] mmHg, P = 0.030) blood pressure values, as well as lower triglyceride concentrations (1.40 [1.18] vs. 1.75 [1.25] mmol/l, P = 0.003). GADab+ men had a lower waist-to-hip ratio compared with GADab- patients. Compared with GADab- patients and control subjects, the GADab+ patients had an increased frequency HLA-DQB1*0201/0302 (13 vs. 4%; P = 0.002) and other genotypes containing the *0302 allele (22 vs. 12%; P = 0.010). However, the frequency of these high-risk genotypes was significantly lower in GADab+ type 2 patients than in type 1 diabetes of young or adult onset (0201/0302 or 0302/X: 36 vs. 66 vs. 64%, P < 0.001). The GADab+ type 2 group did not differ from control subjects with respect to genotypes containing the protective DQB1-alleles *0602 or *0603, nor with respect to the type 1 high-risk genotype in the IDDM1 (Hph1 +/+). We conclude that GADab+ patients differ from both GADab- type 2 diabetic patients and type 1 diabetic patients with respect to beta-cell function, features of the metabolic syndrome, and type 1 diabetes susceptibility genes. Further, we propose that LADA be defined as GADab positivity (>5 relative units) in patients older than 35 years at onset of type 2 diabetes.; Genetic factors influence the development of type II diabetes mellitus, but genetic loci for the most common forms of diabetes have not been identified. A genomic scan was conducted to identify loci linked to diabetes and body-mass index (BMI) in Pima Indians, a Native American population with a high prevalence of type II diabetes. Among 264 nuclear families containing 966 siblings, 516 autosomal markers with a median distance between adjacent markers of 6.4 cM were genotyped. Variance-components methods were used to test for linkage with an age-adjusted diabetes score and with BMI. In multipoint analyses, the strongest evidence for linkage with age-adjusted diabetes (LOD = 1.7) was on chromosome 11q, in the region that was also linked most strongly with BMI (LOD = 3.6). Bivariate linkage analyses strongly rejected both the null hypothesis of no linkage with either trait and the null hypothesis of no contribution of the locus to the covariation among the two traits. Sib-pair analyses suggest additional potential diabetes-susceptibility loci on chromosomes 1q and 7q.; During active disease, patients with systemic-onset juvenile chronic arthritis (S-JCA) demonstrate a rise and fall in serum interleukin-6 (IL-6) that parallels the classic quotidian fever. To investigate the possibility that this cytokine profile results from a difference in the control of IL-6 expression, we examined the 5' flanking region of the IL-6 gene for polymorphisms. A G/C polymorphism was detected at position -174. In a group of 383 healthy men and women from a general practice in North London, the frequency of the C allele was 0.403 (95% confidence interval 0.37-0.44). In comparison, 92 patients with S-JCA had a different overall genotype frequency, especially those with onset of disease at < 5 yr of age. This was mainly due to the statistically significant lower frequency of the CC genotype in this subgroup. When comparing constructs of the 5' flanking region (-550-+61 bp) in a luciferase reporter vector transiently transfected into HeLa cells, the -174C construct showed 0.624+/-0.15-fold lower expression than the -174G construct. After stimulation with LPS or IL-1, expression from the -174C construct did not significantly change after 24 h, whereas expression from the -174G construct increased by 2.35+/-0.10- and 3.60+/-0.26-fold, respectively, compared with the unstimulated level. Plasma levels of IL-6 were also measured in 102 of the healthy subjects, and the C allele was found to be associated with significantly lower levels of plasma IL-6. These results suggest that there is a genetically determined difference in the degree of the IL-6 response to stressful stimuli between individuals. The reduced frequency of the potentially protective CC genotype in young S-JCA patients may contribute to its pathogenesis. Similarly the individual's IL-6 genotype may be highly relevant in other conditions where IL-6 has been implicated, such as atherosclerosis.; Ossification of the posterior longitudinal ligament of the spine (OPLL) is a common form of human myelopathy caused by a compression of the spinal cord by ectopic ossification of spinal ligaments. To elucidate the genetic basis for OPLL, we have been studying the ttw (tiptoe walking; previously designated twy) mouse, a naturally occurring mutant which exhibits ossification of the spinal ligaments very similar to human OPLL (refs 3,4). Using a positional candidate-gene approach, we determined the ttw phenotype is caused by a nonsense mutation (glycine 568 to stop) in the Npps gene which encodes nucleotide pyrophosphatase. This enzyme regulates soft-tissue calcification and bone mineralization by producing inorganic pyrophosphate, a major inhibitor of calcification. The accelerated bone formation characteristic of ttw mice is likely to result from dysfunction of NPPS caused by predicted truncation of the gene product, resulting in the loss of more than one-third of the native protein. Our results may lead to novel insights into the mechanism of ectopic ossification and the aetiology of human OPLL.; Type 2 diabetes mellitus is a common chronic disease that is thought to have a substantial genetic basis. Identification of the genes responsible has been hampered by the complex nature of the syndrome. Abnormalities in insulin secretion and insulin action predict the development of type 2 diabetes and are, themselves, highly heritable traits. Since fewer genes may contribute to these precursors of type 2 diabetes than to the overall syndrome, such genes may be easier to identify. We, therefore, undertook an autosomal genomic scan to identify loci linked to prediabetic traits in Pima Indians, a population with a high prevalence of type 2 diabetes. 363 nondiabetic Pima Indians were genotyped at 516 polymorphic microsatellite markers on all 22 autosomes. Linkage analyses were performed using three methods (single-marker, nonparametric multipoint [MAPMAKER/SIBS], and variance components multipoint). These analyses provided evidence for linkage at several chromosomal regions, including 3q21-24 linked to fasting plasma insulin concentration and in vivo insulin action, 4p15-q12 linked to fasting plasma insulin concentration, 9q21 linked to 2-h insulin concentration during oral glucose tolerance testing, and 22q12-13 linked to fasting plasma glucose concentration. These results suggest loci that may harbor genes contributing to type 2 diabetes in Pima Indians. None of the linkages exceeded a LOD score of 3.6 (a 5% probability of occurring in a genome-wide scan). These findings must, therefore, be considered tentative until extended in this population or replicated in others.; Like obese humans, Zucker diabetic fatty (ZDF) rats exhibit early beta cell compensation for insulin resistance (4-fold beta cell hyperplasia) followed by decompensation (>50% loss of beta cells). In prediabetic and diabetic ZDF islets, apoptosis measured by DNA laddering is increased 3- and >7-fold, respectively, compared with lean ZDF controls. Ceramide, a fatty acid-containing messenger in cytokine-induced apoptosis, was significantly increased (P < 0.01) in prediabetic and diabetic islets. Free fatty acids (FFAs) in plasma are high (>1 mM) in prediabetic and diabetic ZDF rats; therefore, we cultured prediabetic islets in 1 mM FFA. DNA laddering rose to 19.6% vs. 4.6% in lean control islets, preceded by an 82% increase in ceramide. C2-Ceramide without FFA induced DNA laddering, but fumonisin B1, a ceramide synthetase inhibitor, completely blocked FFA-induced DNA laddering in cultured ZDF islets. [3H]Palmitate incorporation in [3H]ceramide in ZDF islets was twice that of controls, but [3H]palmitate oxidation was 77% less. Triacsin C, an inhibitor of fatty acyl-CoA synthetase, and troglitazone, an enhancer of FFA oxidation in ZDF islets, both blocked DNA laddering. These agents also reduced inducible nitric oxide (NO) synthase mRNA and NO production, which are involved in FFA-induced apoptosis. In ZDF obesity, beta cell apoptosis is induced by increased FFA via de novo ceramide formation and increased NO production.; Interleukin 1beta (IL-1beta)-induced beta cell cytotoxicity has been implicated in the autoimmune cytotoxicity of insulin-dependent diabetes mellitus. These cytotoxic effects may be mediated by nitric oxide (NO). Since long-chain fatty acids (FFA), like IL-1beta, upregulate inducible nitric oxide synthase and enhance NO generation in islets, it seemed possible that islets might be protected from IL-1beta-induced damage by lowering their lipid content. We found that IL-1beta-induced NO production varied directly and islet cell viability inversely with islet triglyceride (TG) content. Fat-laden islets of obese rats were most vulnerable to IL-1beta, while moderately fat-depleted islets of food-restricted normal rats were less vulnerable than those of free-feeding normal rats. Severely lipopenic islets of rats made chronically hyperleptinemic by adenoviral leptin gene transfer resisted IL-1beta cytotoxicity even at 300 pg/ml, the maximal concentration. Troglitazone lowered islet TG in cultured islets from both normal rats and obese, leptin-resistant rats and reduced NO production and enhanced cell survival. We conclude that measures that lower islet TG content protect against IL-1beta-induced NO production and cytotoxicity. Leptin or troglitazone could provide in vivo protection against insulin-dependent diabetes mellitus.; The onset of NIDDM in obese Zucker diabetic fatty (fa/fa) rats is preceded by a striking increase in the plasma levels of free fatty acids (FFAs) and by a sixfold rise in triglyceride content in the pancreatic islets. The latter finding provides clear evidence of elevated tissue levels of long-chain fatty acyl CoA, which can impair beta-cell cell function. To determine if the triglyceride accumulation is entirely the passive consequence of high plasma FFA levels or if prediabetic islets have an increased lipogenic capacity that might predispose to NIDDM, the metabolism of long-chain fatty acids was compared in islets of obese prediabetic and nonprediabetic Zucker diabetic fatty (ZDF) rats and of lean Wistar and lean ZDF rats. When cultured in 1 or 2 mmol/l FFA, islets of both female and male obese rats accumulated, respectively, 7 and 15 times as much triglyceride as islets from lean rats exposed to identical FFA concentrations. The esterification of [14C]palmitate and 9,10-[3H]palmitate was increased in islets of male obese rats and could not be accounted for by defective oxidation of 9,10-[3H]-palmitate. Glycerol-3-PO4 acyl-transferase (GPAT) activity was 12 times that of controls. The mRNA of GPAT was increased in islets of obese rats. We conclude that, in the presence of comparable elevations in FFA concentrations, the islets of obese prediabetic rats have a higher lipogenic capacity than controls. This could be a factor in their high risk of diabetes.; Non-insulin-dependent diabetes mellitus (NIDDM) is considered a polygenic disorder in which insulin resistance and insulin secretory defect are the major etiologic factors. Homozygous mice with insulin receptor substrate-1 (IRS-1) gene knockout showed normal glucose tolerance associated with insulin resistance and compensatory hyperinsulinemia. Heterozygous mice with beta cell glucokinase (GK) gene knockout showed impaired glucose tolerance due to decreased insulin secretion to glucose. To elucidate the interplay between insulin resistance and insulin secretory defect for the development of NIDDM, we generated double knockout mice with disruption of IRS-1 and beta cell GK genes by crossing the mice with each of the single gene knockout. The double knockout mice developed overt diabetes. Blood glucose levels 120 min after intraperitoneal glucose load (1.5 mg/g body wt) were 108 +/- 24 (wild type), 95 +/- 26 (IRS-1 knockout), 159 +/- 68 (GK knockout), and 210 +/- 38 (double knockout) mg/dl (mean +/- SD) (double versus wild type, IRS-1, or GK; P < 0.01). The double knockout mice showed fasting hyperinsulinemia and selective hyperplasia of the beta cells as the IRS-1 knockout mice (fasting insulin levels: 0.38 +/- 0.30 [double knockout], 0.35 +/- 0.27 [IRS-1 knockout] versus 0.25 +/- 0.12 [wild type] ng/ml) (proportion of areas of insulin-positive cells to the pancreas: 1.18 +/- 0.68%; P < 0.01 [double knockout], 1.20 +/- 0.93%; P < 0.05 [IRS-1 knockout] versus 0.54 +/- 0.26% [wild type]), but impaired insulin secretion to glucose (the ratio of increment of insulin to that of glucose during the first 30 min after load: 31 [double knockout] versus 163 [wild type] or 183 [IRS-1 knockout] ng insulin/mg glucose x 10(3)). In conclusion, the genetic abnormalities, each of which is nondiabetogenic by itself, cause overt diabetes if they coexist. This report provides the first genetic reconstitution of NIDDM as a polygenic disorder in mice.; NIDDM is a polygenic disease characterized by insulin resistance in muscle, fat, and liver, followed by a failure of pancreatic beta cells to adequately compensate for this resistance despite increased insulin secretion. Mice double heterozygous for null alleles in the insulin receptor and insulin receptor substrate-1 genes exhibit the expected approximately 50% reduction in expression of these two proteins, but a synergism at a level of insulin resistance with 5- to 50-fold elevated plasma insulin levels and comparable levels of beta cell hyperplasia. At 4-6 months of age, 40% of these double heterozygotes become overtly diabetic. This NIDDM mouse model in which diabetes arises in an age-dependent manner from the interaction between two genetically determined, subclinical defects in the insulin signaling cascade demonstrates the role of epistatic interactions in the pathogenesis of common diseases with non-Mendelian genetics.; The Ca(2+)-sensitive and mitochondrial enzyme FAD-linked glycerophosphate dehydrogenase (m-GDH) represents an essential component of the pancreatic B-cell glucose-sensing device. This report deals with the first identified case of mutation in the calcium-binding domain of the m-GDH gene in a patient with type-2 diabetes and his glucose-intolerant half sister. Single strand conformation polymorphism analysis indeed revealed an abnormal mobility of the 32P-labelled polymerase chain reaction product in these two subjects. The corresponding base pair mutations and amino acid changes were documented. In the diabetic proband, the relative extent of the Ca(2+)-induced activation of m-GDH in CD3+ T-lymphocytes was lower than in his brother with a normal m-GDH gene sequence.; To determine whether metformin or troglitazone can delay the onset of diabetes in the Zucker diabetic fatty (ZDF) rat, lean control, fatty, and ZDF rats received metformin, troglitazone, or no treatment from 6 to 12 wk of age. Glucose, insulin, triglyceride (TG), and free fatty acid (FFA) levels and glucose stimulated insulin secretion by the perfused pancreas were measured. Metformin-treated rats gained significantly less weight. Both drugs prevented hyperglycemia by 12 wk in diabetic rats and significantly reduced TG and FFA levels. Insulin secretion at low glucose was elevated in untreated fatty and diabetic animals, and the increment in diabetic animals produced by glucose perfusion was attenuated compared with lean and fatty rats. Both drugs reduced basal insulin secretion in fatty and diabetic rats and improved glucose responsiveness in diabetic rats. Metformin and troglitazone delay the onset of diabetes in the ZDF rat. The significantly improved insulin secretory response of the pancreas undoubtedly contributes to the improved glucose tolerance.; Non-insulin dependent diabetes mellitus (NIDDM) is a major public health problem, but its aetiology remains poorly understood. We have performed a comprehensive study of the genetic basis of diabetes in the Goto-Kakizaki (GK) rat, the most widely used animal model of non-obese NIDDM. The genetic dissection of NIDDM using this model has allowed us to map three independent loci involved in the disease. In addition, we identify a major factor affecting body weight, but not glucose tolerance, on chromosome 7 and map a further 10 regions that are suggestive for linkage. We conclude that NIDDM is polygenic and fasting hyperglycaemia and postprandial hyperglycaemia clearly have distinct genetic bases.; Goto-Kakizaki (GK) rats are a well characterized model for non-insulin dependent diabetes mellitus (NIDDM). We have used a combination of physiological and genetic studies to identify quantitative trait loci (QTLs) responsible for the control of glucose homeostasis and insulin secretion in a F2 cohort bred from spontaneously diabetic GK rats. The genetic dissection of NIDDM allowed us to map up to six independently segregating loci predisposing to hyperglycaemia, glucose intolerance or altered insulin secretion, and a seventh locus implicated in body weight. QTLs implicated in glucose tolerance and adiposity map to the same region of rat chromosome 1, and may indicate the influence of a single locus. Our study demonstrates that distinct combinations of genetic loci are responsible for different physiological characteristics associated with the diabetic phenotype in the GK rat, and it constitutes an important step for directing the search for the genetic factors involved in human NIDDM.; NA; Hyperinsulinemia, loss of glucose-stimulated insulin secretion (GSIS), and peripheral insulin resistance coexist in non-insulin-dependent diabetes mellitus (NIDDM). Because free fatty acids (FFA) can induce these same abnormalities, we studied their role in the pathogenesis of the NIDDM of obese Zucker diabetic fatty (ZDF-drt) rats from 5 weeks of age (before the onset of hyperglycemia) until 14 weeks. Two weeks prior to hyperglycemia, plasma FFA began to rise progressively, averaging 1.9 +/- 0.06 mM at the onset of hyperglycemia (P < 0.001 vs. controls). At this time GSIS was absent and beta-cell GLUT-2 glucose transporter was decreased. The triacylglycerol content of prediabetic islets rose to 10 times that of controls and was correlated with plasma FFA (r = 0.825; P < 0.001), which, in turn, was correlated with the plasma glucose concentration (r = 0.873; P < 0.001). Reduction of hyperlipacidemia to 1.3 +/- 0.07 mM by pair feeding with lean littermates reduced all beta-cell abnormalities and prevented hyperglycemia. Normal rat islets that had been cultured for 7 days in medium containing 2 mM FFA exhibited increased basal insulin secretion at 3 mM glucose, and first-phase GSIS was reduced by 68%; in prediabetic islets, first-phase GSIS was reduced by 69% by FFA. The results suggest a role for hyperlipacidemia in the pathogenesis of NIDDM; resistance to insulin-mediated antilipolysis is invoked to explain the high FFA despite hyperinsulinemia, and sensitivity of beta cells to hyperlipacedemia is invoked to explain the FFA-induced loss of GSIS.; Glut2, the facilitative glucose transporter isoform expressed in pancreatic beta cells, is believed to play a role in glucose-stimulated insulin secretion. Two polymorphisms that result in amino acid substitutions have been reported in the human Glut2 gene (Tanizawa, Y., Riggs, A. C., Chiu, K. C., Janssen, R. C., Bell, D. S. H., Go, R. P. C., Roseman, J. M., Acton, R. T., and Permutt, M. A. (1994) Diabetologia 37, 420-427). A threonine 110-->isoleucine substitution was present at equal frequency in diabetic and control populations, and a valine 197-->isoleucine substitution was discovered in a single allele of a patient with non-insulin-dependent diabetes. The effect of these amino acid changes on glucose transport activity was tested by expression of the mutant proteins in Xenopus oocytes. The polymorphism at threonine 110 had no effect on the expression of Glut2 protein or the uptake of 2-deoxyglucose. Remarkably, however, the highly conservative valine 197-->isoleucine amino acid change abolished transport activity of the Glut2 transporter expressed in Xenopus oocytes. This represents the first known dysfunctional mutation in a human facilitative glucose transporter protein. The presence of this mutation in a diabetic patient suggests that defects in Glut2 expression may be causally involved in the pathogenesis of non-insulin-dependent diabetes.; Insulin regulates essential pathways for growth, differentiation, and metabolism in vivo. We report a physiologically relevant system for dissecting the molecular mechanisms of insulin signal transduction related to glucose transport. This is an extension of our recently reported method for transfection of DNA into rat adipose cells in primary culture. In the present work, cDNA coding for GLUT4 with an epitope tag (HA1) in the first exofacial loop is used as a reporter gene so that GLUT4 translocation can be studied exclusively in transfected cells. Insulin stimulates a 4.3-fold recruitment of transfected epitope-tagged GLUT4 to the cell surface. Cells cotransfected with the reporter gene and the human insulin receptor gene show an increase in cell surface GLUT4 in the basal state (no insulin) to levels comparable to those seen with maximal insulin stimulation of cells transfected with the reporter gene alone. In contrast, cells overexpressing a naturally occurring tyrosine kinase-deficient mutant insulin receptor (Met1153-->Ile) show no increase in the basal cell surface GLUT4 and no shift in the insulin dose-response curve relative to cells transfected with the reporter gene alone. These results demonstrate that insulin receptor tyrosine kinase activity is essential in insulin-stimulated glucose transport in adipose cells.; The purpose of these experiments was to test the hypothesis that impaired glucose-stimulated insulin secretion in NIDDM is due to mutations in the islet beta cell/liver glucose transporter (GLUT 2) gene. Using oligonucleotide primers flanking each of the 11 exons, the structural portion of the gene was studied by PCR-SSCP analysis. DNA from African-American females (n = 48), who had gestational diabetes but developed overt NIDDM after delivery, was studied. Each SSCP variant was sequenced directly from genomic DNA. Two amino acid substitutions from the previously reported sequence were found, one in exon 3 and the other in exon 4B. Four additional silent mutations in the coding region, and six intron mutations outside the splice junction consensus sequences, were also identified. The mutation GTC x ATC in exon 4B substituted Val197 to Ile197. This amino acid substitution was found in only one NIDDM patient in a single allele, and was not found in 52 control subjects. This residue exists in the fifth membrane spanning domain, and Val at this position is conserved in mouse and rat GLUT 2, and human GLUT 1 to GLUT 4. The other codon change in exon 3, ACT x ATT, substituted Thr110 to Ile110 in the second membrane spanning domain. To determine the frequency of this non-conservative amino acid substitution, a PCR-LCR assay was developed. This assay was simple and highly specific for detection of this single nucleotide substitution. The allelic frequency of the ATT (Ile110) in NIDDM patients (39.6%, n = 48) and that in controls (47.1%, n = 52) did not differ (p = 0.32, Fisher's exact test).(ABSTRACT TRUNCATED AT 250 WORDS); NA; NA; Members of three families with maturity onset diabetes of youth (MODY) and seven with "common" type 2 diabetes were typed for six DNA markers (H-RAS, INS, HBBC, PTH, CALC1, CAT) on the short arm of chromosome 11. Using conventional pairwise linkage analysis, close linkage in the MODY families was excluded for all six markers. By multipoint analysis and a genetic map of the short arm of chromosome 11, MODY was excluded from a region of at least 35 and up to 60 centiMorgans (cM) on the short arm of chromosome 11. Multipoint analysis in the type 2 families also excludes linkage to the INS, H-RAS region of at least 3 and up to 30 cM. This study using multipoint linkage analysis in non-insulin dependent diabetes provides strong evidence against a role for mutations in or around the insulin gene in the causation of MODY or type 2 diabetes in the families studied.; The intracellular domain of the insulin receptor possesses activity as a tyrosine-specific protein kinase. The receptor tyrosine kinase is stimulated by insulin binding to the extracellular domain of the receptor. Previously, we have identified a patient with a genetic form of insulin resistance who is heterozygous for a mutation substituting Ile for Met1153 in the tyrosine kinase domain of the receptor near the cluster of the three major autophosphorylation sites (Tyr1158, Tyr1162, and Tyr1163). In this investigation, the Ile1153 mutant receptor was expressed by transfection of mutant cDNA into NIH-3T3 cells. The mutation impairs receptor tyrosine kinase activity and also inhibits the ability of insulin to stimulate 2-deoxyglucose uptake and thymidine incorporation. These data support the hypothesis that the receptor tyrosine activity plays a necessary role in the ability of the receptor to mediate insulin action in vivo. Furthermore, expression of the Ile1153 mutant receptor exerted a dominant negative effect to inhibit the ability of endogenous murine receptors for insulin and insulin-like growth factor I to mediate their actions upon the cell. This observation is consistent with previous suggestions that mutant receptors dimerize with wild type receptors, thereby creating hybrid molecules which lack biological activity. The dominant negative effect of the mutant receptor may explain the dominant mode of inheritance of insulin resistance caused by the Ile1153 mutation. Finally, the mutation inhibits the ability of insulin to stimulate receptor endocytosis. This may explain the normal number of insulin receptors on the surface of the patient's cells in vivo. Despite the presence of markedly elevated levels of insulin in the patient's plasma, the receptors were resistant to down-regulation.; A population of 103 patients with non-insulin-dependent diabetes mellitus (NIDDM) was screened for mutations in the tyrosine kinase domain of the insulin receptor gene. Patient genomic DNAs corresponding to exons 17-21 of the insulin receptor gene have been amplified by polymerase chain reaction and analyzed by denaturing gradient gel electrophoresis (DGGE). One patient was identified with an altered pattern of mobility of exon 20 in the DGGE assay. Direct sequence of amplified DNA showed a single nucleotide substitution in the codon 1152 (CGG-- greater than CAG), resulting in the replacement of Arg with Gln. Two bands appeared in the sequence of exon 20 of the insulin receptor (nucleotide position 3584), indicating that this patient was heterozygous for the mutation. Insulin binding to intact erythrocytes from the patient was in the normal range. Although autophosphorylation of the purified insulin receptor also seemed normal, its kinase activity toward the exogenous substrate poly Glu:Tyr (4:1) was undetectable. This mutation may impair insulin receptor kinase and contribute to insulin resistance in this patient.; Based on the sequence of cDNA encoding the intracellular domain of the insulin receptor beta-subunit, we recently defined a heterozygous point mutation causing a Ser for Trp substitution at position 1200 in the tyrosine kinase domain of a patient (BI-2) with the type A syndrome of insulin resistance. We have now sequenced the remainder of BI-2's insulin receptor cDNA-coding region and find no additional alterations in the encoded proreceptor protein. The nucleotide sequence of cDNA encoding the portion of the beta-subunit which includes Trp1200 was normal in BI-2's unaffected mother. Hybridization of a mutant allele-specific oligonucleotide to polymerase chain reaction-amplified cDNA confirmed the presence of the mutant allele in the proband and excluded it in her unaffected sister and mother, 18 normal control subjects, and six other subjects with insulin resistance. To determine whether this mutation had functional consequences for receptor signalling, we reconstructed it into a full-length insulin receptor cDNA expression vector. Chinese hamster ovary cells were transfected with mutant cDNA, and the expressed insulin receptors were compared to receptors expressed by cells transfected with wild-type receptor cDNA. Both mutant and wild-type receptors were properly processed into receptor alpha- and beta-subunits, were expressed on the cell surface, and displayed similar insulin-binding affinity. In contrast, insulin-stimulated autophosphorylation of the mutant receptors was severely impaired, whether assessed in intact cells or with a partially purified receptor preparation.(ABSTRACT TRUNCATED AT 250 WORDS); If a single gene produced insulin resistance, with environmental effects creating some additional variance, insulin action might be distributed as a mixture of two normal distributions if the gene is dominant or recessive or as a mixture of three normal distributions if the gene is codominant. To estimate maximal insulin-stimulated glucose uptake rates (MaxMs), hyperinsulinemic-euglycemic clamps were performed on 245 nondiabetic Pima Indians (126 men, 119 women). Five models (for 1, 2, 3, 4, or 5 components each, normally distributed with a common variance) were fitted to the frequency distribution of MaxM by iterative maximum-likelihood estimation. The three-component model fit the data significantly better than a single normal distribution (chi 2 = 14.3 with 4 df P less than .01) or a mixture of two normal distributions (chi 2 = 9.9 with 2 df, P less than .01). Mixtures of four or five normal distributions did not fit the data significantly better than a mixture of three normal distributions. The first component of the distribution comprised 23%, the second 48%, and the third 29% of the total distribution. Similarly, the frequency distributions of fasting plasma insulin concentrations and a principal component score derived from MaxM and fasting insulin were best fitted by a mixture of three normal distributions. These results are consistent with the hypothesis that among Pimas, insulin resistance is determined by a single gene with a codominant mode of inheritance. Segregation analyses of studies performed in pedigrees are indicated to prove or disprove this genetic hypothesis.; Liver function improved after a two-week hypocaloric protein-rich diet and metabolic surgery in patients with obesity and T2DM. These data suggest that a two-week diet for this group of patients prior to abdominal surgery could improve a presumably impaired liver function.; ARISE-HF, NCT04083339.; We reveal a plasma miRNA signature for DM that includes loss of endothelial miR-126. These findings might explain the impaired peripheral angiogenic signaling in patients with DM.; MiR-125a is over-expressed in liver in hyperglycaemic GK rats relative to normoglycaemic BN rats, and our array data also suggest miR-125a is over-expressed in adipose tissue. We demonstrate the use of in-silico tools to provide the basis for further investigation of the potential role of miR-125a in T2D. In particular, the enrichment of predicted miR-125a target genes among differentially expressed genes has identified likely target genes and indicates that integrating global miRNA and mRNA expression data may give further insights into miRNA-mediated regulation of gene expression.; The biological mechanism of a recent discovered association of type 2 diabetes with the ACAA-insertion/deletion polymorphism at the 3'UTR of the IGF2R gene has remained unclear. A very recently emerging novel polymorphic control layer by microRNAs (miRNAs) makes it possible to elucidate this issue. In this study, a prediction by web tools MicroInspector and miRanda demonstrated that DNA sequence polymorphism (DSPs) ACAA-insertion/deletion in IGF2R 3'UTR is located within the hsa-miR-657 and hsa-miR-453 binding sites. And luciferase reporter assay revealed that hsa-miR-657 acts directly at the 3'UTR of the IGF2R. Furthermore, ACAA-deletion exerted a further repression compared with ACAA-insertion, indicating that hsa-miR-657 regulates IGF2R gene expression in a polymorphic control manner. Importantly, we also demonstrated that hsa-miR-657 can translationally regulate the IGF2R expression levels in Hep G2 cells. Thus, our findings testify the possibility that the ACAA-insertion/deletion polymorphism may result in the change of IGF2R expression levels at least in part by hsa-miR-657-mediated regulation, contributing to the elucidation for the pathogenesis of type 2 diabetes and raise the possibility that miRNAs or in combination with functional DNA sequence polymorphism may be valuable in the treatment of human type 2 diabetes. |
