Gender-dependent associations of CDKN2A/2B, KCNJ11, POLI, SLC30A8, and TCF7L2 variants with type 2 diabetes in (North African) Tunisian Arabs

We investigated the impact of gender on T2DM association with confirmed susceptibility loci. CDKN2A/2B rs10811661, KCNJ11 rs5219, and TCF7L2 rs7903146 were associated with T2DM in females, while POLI rs488846 was associated with T2DM among males; the association of SLC30A8 rs13266634 and TCF7L2 rs4506565, rs12243326, and rs12255372 with T2DM was gender-independent.     

Transcription factor 7-like 2 (TCF7L2) gene polymorphism rs7903146 is associated with stroke in type 2 diabetes patients with long disease duration

Associations between TCF7L2 SNP and diabetic complications and diabetes-related factors were investigated. Subjects with rs7903146 variant had significantly higher prevalence of stroke (24.1% vs. 11.1%; P = 0.039) among subjects exhibiting a long disease duration (≥10 years). In conclusion, the TCF7L2 SNP variant may confer a higher risk of stroke in diabetic patients.     

Association of TCF7L2 rs7903146 Gene Polymorphism with the Risk of NAFLD and CAD in the Chinese Han Population

Background and Aims: Coronary artery disease (CAD) is a major cause of morbidity and mortality in patients with non-alcoholic fatty liver disease (NAFLD). Previous studies have suggested that TCF7L2 rs7903146 was related to the risk of developing NAFLD but the conclusions are not consistent and no related study has been conducted in Chinese populations. The aim of this study was to investigate the association between TCF7L2 rs7903146 and the risk of developing NAFLD and CAD in a Chinese Han population.Methods: TCF7L2 rs7903146 genotypes were measured by the MALDI-TOF-MS from 143 NAFLD patients, 159 CAD patients, 131 NAFLD + CAD patients, and 212 healthy controls. The demographic data and serum lipid profiles of all subjects were collected. The distributions of genotype and allele frequency in each group were also tested. Logistic regression was used to investigate the risk of TCF7L2 rs7903146 with NAFLD and CAD. All statistical analyses were conducted using SPSS 23.0.Results: There were no significant differences in the distributions of TCF7L2 rs7903146 genotype and allele frequency in each of the two groups, and the TCF7L2 rs7903146 CT + TT genotype did not increase the risk of developing NAFLD, CAD, and NAFLD + CAD. Except for body mass index in the control group, the differences of clinical parameters between the TCF7L2 rs7903146 T allele carriers and non-carriers in each group were not significant. In the non-obese group, the TCF7L2 rs7903146 CT + TT genotype was a protective factor for the development of NAFLD in the non-obese subjects (odds ratio=0.359, 95% confidence interval: 0.134-0.961, p = 0.041).Conclusions: TCF7L2 rs7903146 was not associated with the risk of developing NAFLD, CAD, and NAFLD + CAD in the Chinese Han population. In the non-obese population, the TCF7L2 rs7903146 CT + TT genotype was a protective factor against the development of NAFLD.     

Association between plasma levels of proprotein convertase subtilisin/kexin type 9 (PCSK9) and lipids with rs7903146 polymorphisms of the TCF7L2 gene in diabetic patients

The rs7903146 polymorphism of TCF7L2 gene is known as the strongest genetic risk factor for type 2 diabetes mellitus (T2DM). The polymorphism is in association with clinical profile of T2DM patients. PCSK9 is a serine protease that promotes LDLR degradation and regulates circulating levels of lipids. The association of this polymorphism with PCSK9 and metabolic profile of diabetic and healthy subjects was investigated. This cross-sectional study was performed on 132 T2DM patients and the same number of healthy subjects. All the participants were genotyped for the rs7903146 single nucleotide polymorphism by the PCR-RFLP method. Metabolic profile including plasma levels of PCSK9, triglycerides, total cholesterol, non-HDL cholesterol, LDL cholesterol, HDL cholesterol, fasting plasma glucose, and HBA1C was measured. PCSK9, total cholesterol, and LDL-C levels were lower in the diabetic patients as compared to the healthy subjects. There were also direct and significant associations between PCSK9 and TG, TC, LDL-C, and non HDL-C in the subjects. Values of plasma glucose, HbA1c, PCSK9, TC, and LDL-C were higher in patients with TT genotype, but the differences were not statistically significant for all. A positive Spearman correlation was found between PCSK9 levels and the genotypes in all the participants. The results confirm the association of rs7903146 in the TCF7L2 gene with metabolic parameters and PCSK9. The T allele was associated with higher lipid and PCSK9 levels.

     

Contribution of common variants of ENPP1, IGF2BP2, KCNJ11, MLXIPL,PPARγ, SLC30A8 and TCF7L2 to the risk of type 2 diabetes in Lebanese and Tunisian Arabs

BackgroundWhile several type 2 diabetes mellitus (T2DM) susceptibility loci identified through genome-wide association studies (GWAS) have been replicated in many populations, their association in Arabs has not been reported. For this reason, the present study looked at the contribution of ENNP1 (rs1044498), IGF2BP2 (rs1470579), KCNJ11 (rs5219), MLXIPL (rs7800944), PPARγ (rs1801282), SLC30A8 (rs13266634) and TCF7L2 (rs7903146) SNPs to the risk of T2DM in Lebanese and Tunisian Arabs.MethodsStudy subjects (case/controls) were Lebanese (751/918) and Tunisians (1470/838). Genotyping was carried out by the allelic discrimination method.ResultsIn Lebanese and Tunisians, neither ENNP1 nor MLXIPL was associated with T2DM, whereas TCF7L2 was significantly associated with an increased risk of T2DM in both the Lebanese [P < 0.001; OR (95% CI): 1.38 (1.20–1.59)] and Tunisians [P < 0.001; OR (95% CI): 1.36 (1.18–1.56)]. Differential associations of IGF2BP2, KCNJ11, PPARγ and SLC30A8 with T2DM were noted in the two populations. IGF2BP2 [P = 1.3 × 10^?5; OR (95% CI): 1.66 (1.42–1.94)] and PPARγ [P = 0.005; OR (95% CI): 1.41 (1.10–1.80)] were associated with T2DM in the Lebanese, but not Tunisians, while KCNJ11 [P = 8.0 × 10^?4; OR (95% CI): 1.27 (1.09–1.47)] and SLC30A8 [P = 1.6 × 10^?5; OR (95% CI): 1.37 (1.15–1.62)] were associated with T2DM in the Tunisians, but not Lebanese, after adjusting for gender and body mass index.ConclusionT2DM susceptibility loci SNPs identified through GWAS showed differential associations with T2DM in two Arab populations, thus further confirming the ethnic contributions of these variants to T2DM susceptibility.     

TCF7L2基因单核苷酸多态性与汉族2型糖尿病遗传易感性关系的研究

目的探讨TCF7L2基因单核苷酸多态性与汉族人2型糖尿病遗传易感性的关系。方法无血缘关系江苏地区汉族人1535例,分为2型糖尿病组（T2DM）、糖耐量减低组（IGT）和正常糖耐量组（NGT）,LDR法检测TCF7L2基因rs7903146（C／T）及rs12255372（G／T）单核苷酸多态性。结果（1）T2DM、IGT组rs7903146位点T等位基因频率均高于NGT组,但差异无统计学意义;（2）糖代谢异常组rs7903146位点CT基因型频率及T等位基因频率则显著高于NGT组（P均〈0．05）,T等位基因参与糖代谢异常发生的相对风险为1．589,人群归因危险度为2．1％。结论TCF7L2基因单核苷酸多态分布存在明显的种族异质性,rs7903146位点T突变可能是中国汉族人群糖代谢异常发生的遗传因素之一。     

Pleiotropic effects of TCF7L2 gene variants and its modulation in the metabolic syndrome: from the LIPGENE study

Aims/hypothesisVariants of the TCF7L2 gene predict the development of type 2 diabetes mellitus (T2DM). We investigated the associations between gene variants of TCF7L2 and clinical features of the metabolic syndrome (MetS) (an entity often preceeding T2DM), and their interaction with non-genetic factors, including plasma saturated fatty acids (SFA) concentration and insulin resistance (IR).MethodsFasting lipid profiles, insulin sensitivity, insulin secretion, anthropometrics, blood pressure and 10 gene variations of the TCF7L2 gene were determined in 450 subjects with MetS.ResultsSeveral single nucleotide polymorphisms (SNP) showed phenotypic associations independent of SFA or IR. Carriers of the rare T allele of rs7903146, and of three other SNPs in linkage disequilibrium with rs7903146, had lower blood pressure and insulin secretion. High IR and the presence of the T-allele of rs7903146 acted synergistically to define those with reduced insulin secretion. Carriers of the minor allele of rs290481 exhibited an altered lipid profile, with increased plasma levels of apolipoprotein B, non-esterified fatty acids, cholesterol and apolipoprotein B in triglyceride rich lipoproteins, and LDL cholesterol. Carriers of the minor allele of rs11196224 that had higher plasma SFA levels showed elevated procoagulant/proinflammatory biomarkers, impaired insulin secretion and increased IR, whereas carriers of the minor allele of rs17685538 with high plasma SFA levels exhibited higher blood pressure.Conclusions/interpretationSNP in the TCF7L2 gene are associated with differences in insulin secretion, blood pressure, blood lipids and coagulation in MetS patients, and may be modulated by SFA in plasma or IR.     

<Emphasis Type="Italic">TCF7L2</Emphasis> single nucleotide polymorphisms,cardiovascular disease and all-cause mortality: the Atherosclerosis Risk in Communities (ARIC) study

Aims/hypothesis We hypothesised that TCF7L2 single nucleotide polymorphisms (SNPs) are associated with cardiovascular disease (CVD) and that the associations differ in diabetic and non-diabetic persons. Methods Our analysis included black and white participants from the Atherosclerosis Risk in Communities study who were free of prevalent CVD at baseline and had been genotyped for rs7903146, rs12255372, rs7901695, rs11196205 and rs7895340 (n = 13,369). Cox proportional hazard regression was used to estimate the associations between polymorphisms and incident events; logistic and linear regression were used for associations with baseline risk factor levels. Results TCF7L2 SNPs were not significantly associated with incident coronary heart disease, ischaemic stroke, CVD, prevalent peripheral artery disease (PAD) or all-cause mortality in the full cohort or when stratified by race. Conclusions/interpretation In the whole cohort, TCF7L2 SNPs were not associated with incident CVD, all-cause mortality or prevalent PAD. This result suggests that the increased health risk associated with rs7903146 genotype is specific to diabetes.     

MicroRNA genetic variations: association with type 2 diabetes

MicroRNAs are small single-stranded molecules that have emerged as important genomic regulators in different pathways. Different studies have shown that they are implicated in the metabolism and glucose homeostasis, and therefore, they could also be involved in the pathogenesis of metabolic disorders such as type 2 diabetes (T2DM). The aim of this study was to verify whether genetic variations in candidate microRNA (miRNA or miR) genes could contribute to T2DM susceptibility. We have selected 13 miRNAs as candidate loci according to literature data and to a computational analysis. MicroRNA genes were analyzed by direct sequencing in a cohort of 163 Italian T2DM patients and 185 healthy controls. We identified 6 novel variants never described before and 9 SNPs already described in databases. Five newly identified variants were found only in the cases group. We performed a case/control association study to test the associations of particular alleles/genotypes of identified SNPs with the disease. Two polymorphisms were associated with T2DM susceptibility: in particular, the G allele of rs895819 in hsa-mir-27a has shown a significantly protective effect (OR = 0.58 and P = 0.008), while the G allele of rs531564 in hsa-mir-124a appears to be a risk allele (OR = 2.15, P = 0.008). This is the first report indicating that genetic polymorphisms in miRNA regions could contribute to T2DM susceptibility.