Exome Sequencing and Genetic Testing for MODY

Context: Genetic testing for monogenic diabetes is important for patient care. Given the extensive genetic and clinical heterogeneity of diabetes, exome sequencing might provide additional diagnostic potential when standard Sanger sequencing-based diagnostics is inconclusive. Objective: The aim of the study was to examine the performance of exome sequencing for a molecular diagnosis of MODY in patients who have undergone conventional diagnostic sequencing of candidate genes with negative results. Research Design and Methods: We performed exome enrichment followed by high-throughput sequencing in nine patients with suspected MODY. They were Sanger sequencing-negative for mutations in the HNF1A, HNF4A, GCK, HNF1B and INS genes. We excluded common, non-coding and synonymous gene variants, and performed in-depth analysis on filtered sequence variants in a pre-defined set of 111 genes implicated in glucose metabolism. Results: On average, we obtained 45 X median coverage of the entire targeted exome and found 199 rare coding variants per individual. We identified 0–4 rare non-synonymous and nonsense variants per individual in our a priori list of 111 candidate genes. Three of the variants were considered pathogenic (in ABCC8, HNF4A and PPARG, respectively), thus exome sequencing led to a genetic diagnosis in at least three of the nine patients. Approximately 91% of known heterozygous SNPs in the target exomes were detected, but we also found low coverage in some key diabetes genes using our current exome sequencing approach. Novel variants in the genes ARAP1, GLIS3, MADD, NOTCH2 and WFS1 need further investigation to reveal their possible role in diabetes. Conclusion: Our results demonstrate that exome sequencing can improve molecular diagnostics of MODY when used as a complement to Sanger sequencing. However, improvements will be needed, especially concerning coverage, before the full potential of exome sequencing can be realized

The PPARGC1A Gly482Ser polymorphism is associated with left ventricular diastolic dysfunction in men

<p>Abstract</p> <p>Background</p> <p>The Gly482Ser polymorphism in peroxisome proliferator-activated receptor gamma coactivator-1 alpha (<it>PPARGC1A</it>) has been demonstrated to be associated with diabetes, obesity and hypertension, all of which are important risk factors for left ventricular diastolic dysfunction.</p> <p>Methods</p> <p>The <it>PPARGC1A </it>Gly482Ser polymorphism was genotyped in a community-based cohort of 499 men and 533 women, who also underwent an echocardiographic examination to determine their left ventricular diastolic function. The association between the polymorphism and the presence of diastolic dysfunction was evaluated using logistic regression models.</p> <p>Results</p> <p>The Ser allele of the <it>PPARGC1A </it>Gly482Ser polymorphism was significantly associated with a lower risk of diastolic dysfunction in men, but not in women. In a model adjusting for potential confounders (age, body mass index, leisure time physical activity, hypertension and diabetes) the results were still significant and substantial (odds ratio 0.13, 95% confidence interval 0.03–0.54, p for trend = 0.004). The results were consistent in a series of models, and they imply a multiplicative, protective effect of the Ser allele, with lower risk of diastolic dysfunction for each copy of the allele.</p> <p>Conclusion</p> <p>The Ser allele of the <it>PPARGC1A </it>Gly482Ser polymorphism was associated with decreased risk of diastolic left ventricular dysfunction in men, but not in women, in our large community-based sample. It was associated with a substantially decreased risk, even after adjustment for potential confounders. The clinical importance of the findings has to be established in further studies.</p

Allelic variations of the vitamin D receptor (VDR) gene are associated with increased risk of coronary artery disease in type 2 diabetics: the DIABHYCAR prospective study

Aim. - Vitamin D deficiency is associated with coronary artery disease (CAD), and the actions of vitamin D are mediated by binding to a specific nuclear vitamin D receptor (VDR). This study investigated the associations of VDR gene variants with CAD in two cohorts of type 2 diabetes patients.Methods. - A cohort of 3137 subjects from the prospective DIABHYCAR study (CAD incidence: 14.8%; follow-up: 4.4 +/- 1.3 years) and an independent, hospital-based population of 713 subjects, 32.3% of whom had CAD, were assessed. Three SNPs in the VDR gene were genotyped: rs1544410 (BsmI); rs7975232 (ApaI); and rs731236 (TaqI).Results. - in the DIABHYCAR cohort, an association was observed between the A allele of BsmI and incident cases of CAD (HR: 1.16, 95% CI: 1.05-1.29; P=0.002). Associations were also observed between BsmI (P = 0.01) and TaqI (P=0.04) alleles and baseline cases of CAD. the AAC haplotype (BsmI/ApaI/TaqI) was significantly associated with an increased CAD prevalence at the end of the study compared with the GCT haplotype (OR: 1.12, 95% CI: 1.02-1.28; P = 0.04). in a cross-sectional study of the independent hospital-based cohort, associations of ApaI (P=0.009) and TaqI (P=0.03) alleles with CAD were observed, with similar haplotype results (OR: 1.33, 95% CI: 1.03-1.73; P=0.03).Conclusion. - the haplotype comprising the minor allele of BsmI, major allele of ApaI and minor allele of TaqI of VDR (AAC) was associated with an increased risk of CAD in type 2 diabetes patients. This effect was independent of the effects of other known cardiovascular risk factors. (C) 2013 Published by Elsevier Masson SAS.Societe Francophone du Diabete (SFD; French Diabetes Society)Association Diabete Risque Vasculaire (ADRV; Diabetes Vascular Risk Association), FranceMinistere de l'Enseignement Superieur et de la Recherche (MESR; Ministry of Higher Education and Research), FranceCoordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)INSERM, Res Unit 695, F-75018 Paris, FranceUniv São Paulo, Fac Med, Lab Human Nutr & Metab Dis LIM, BR-01246903 São Paulo, BrazilCochin Hosp, AP HP, Dept Immunol & Diabetol, F-75014 Paris, FranceUniv Paris 05, UFR Med, F-75006 Paris, FranceUniv Paris Diderot, Sorbonne Paris Cite, UFR Med, F-75018 Paris, FranceUniversidade Federal de São Paulo, Mol Endocrinol Lab, BR-04039002 São Paulo, BrazilHop La Pitie Salpetriere, AP HP, Dept Cardiol, F-75013 Paris, FranceHop Xavier Bichat, AP HP, Dept Diabetol Endocrinol & Nutr, F-75018 Paris, FranceUniversidade Federal de São Paulo, Mol Endocrinol Lab, BR-04039002 São Paulo, BrazilCAPES: 1798-09-0Web of Scienc