<Emphasis Type="Italic">TCF7L2</Emphasis> and therapeutic response to sulfonylureas in patients with type 2 diabetes

Background  

Variants in the TCF7L2 have been shown to be associated with an increased risk for type 2 diabetes (T2D). Since the association with diabetes could be explained by effects on insulin secretion, we investigated whether patients with diabetes risk alleles at rs7903146 might have an altered hypoglycaemic response to sulfonylureas (SUs).     

Weak or no association of <Emphasis Type="Italic">TCF7L2</Emphasis> variants with Type 2 diabetes risk in an Arab population

Background  

The rs7903146 and rs12255372 variants of TCF7L2 have been strongly associated with type 2 diabetes (T2D) risk in most populations studied to date. Meta-analysis of 27 different studies has resulted in a global OR of 1.46 [1.42–1.51] (rs7903146 variant). Thus far, despite a high incidence of T2D, the role of this variant in Arabs has not been established.     

<Emphasis Type="Italic">TCF7L2</Emphasis> rs7903146 variant does not associate with smallness for gestational age in the French population

Background  

In adults, the TCF7L2 rs7903146 T allele, commonly associated with type 2 diabetes (T2D), has been also associated with a lower body mass index (BMI) in T2D individuals and with a smaller waist circumference in subjects with impaired glucose tolerance.     

Implication of genetic variants near <Emphasis Type="Italic">SLC30A8, HHEX,CDKAL1, CDKN2A/B,IGF2BP2, FTO,TCF2</Emphasis>, <Emphasis Type="Italic">KCNQ1</Emphasis>, and <Emphasis Type="Italic">WFS1</Emphasis> in Type 2 Diabetes in a Chinese population

Background  

Recently, several genome-wide and candidate gene association studies have identified many novel genetic loci for type 2 diabetes (T2D); among these genes, CDKAL1, IGF2BP2, SLC30A8, CDKN2A/B, HHEX, FTO, TCF2, KCNQ1, and WFS1 are the most important. We aimed to determine the effects of these genetic loci associated with T2D in the Chinese Han population of China.     

Type 2 diabetes gene TCF7L2 polymorphism is not associated with fetal and postnatal growth in two birth cohort studies

Background  

An inverse association between birth weight and the risk of developing type 2 diabetes (T2D) in adulthood has been reported. This association may be explained by common genetic variants related to insulin secretion and resistance, since insulin is the most important growth factor in fetal life. The objective of this study was to examine whether T2D gene polymorphism TCF7L2 rs7903146 is associated with growth patterns from fetal life until infancy.     

A Validation Study of Type 2 Diabetes‐related Variants of the TCF7L2, HHEX,KCNJ11, and ADIPOQ Genes in one Endogamous Ethnic Group of North India

The aim of this study was to validate the single nucleotide polymorphisms (SNPs) of four candidate genes (TCF7L2, HHEX, KCNJ11, and ADIPOQ) related to type 2 diabetes (T2D) in an endogamous population of north India; the Aggarwal population, having 18‐clans. This endogamous population model was heavily supported by recent land mark work and we also verified the homogeneity of this population by clan‐based stratification analysis. Two SNPs (rs4506565; rs7903146) in TCF7L2 were found to be significant (p‐value = 0.00191; p‐value = 0.00179, respectively), and odds ratios of 2.1 (dominant‐model) and 2.0 (recessive‐model) respectively, were obtained for this population. The TTT haplotype in the TCF7L2 gene was significantly associated with T2D. Waist‐Hip ratio (WHR), systolic blood pressure (SBP), and age were significant covariates for increasing risk of T2D. Single‐SNP, combined‐SNPs and haplotype analysis provides clear evidence that the causal mutation is near to or within the significant haplotype (TTT) of the TCF7L2 gene. In spite of a culturally‐learned sedentary lifestyle and fat‐enriched dietary habits, WHR rather than body‐mass‐index emerged as a robust predictor of risk for T2D in this population.     

The longitudinal association of common susceptibility variants for type 2 diabetes and obesity with fasting glucose level and BMI

Background  

Variation in the effects of genetic variants on physiological traits over time or with age may alter the trajectories of these traits. However, few studies have investigated this possibility for variants associated with type 2 diabetes or obesity, and these show little consensus. We aimed to characterise the possible longitudinal associations of common diabetes-susceptibility variants in the KCNJ11, PPARG, TCF7L2, IGF2BP2, CDKAL1, SLC30A8 and HHEX gene loci, with fasting glucose level; and of an obesity-associated variant in the FTO gene, with body mass index (BMI).     

Implication of the Pro12Ala polymorphism of the <Emphasis Type="Italic">PPAR-gamma 2</Emphasis>gene in type 2 diabetes and obesity in the French population

Background  

The Pro12Ala Single Nucleotide Polymorphism (SNP) of the Peroxisome Proliferator-Activated Receptor gamma 2 (PPAR-gamma 2) has been associated with insulin resistance and type 2 diabetes (T2D) and also inconsistently with obesity. The aim of this study was to evaluate the impact of this SNP with regards to T2D and childhood and adult obesity in the French Caucasian population.     

Use of genomic panels to determine risk of developing type 2 diabetes in the general population: a targeted evidence-based review

This evidence review addresses whether type 2 diabetes genomic risk panels improve health outcomes (e.g., reduce rates of developing type 2 diabetes) in low- or high-risk adults; two clinical scenarios promulgated by commercial companies offering such testing. Evidence for the analytic validity of available genomic profiles was inadequate. Clinical validity ranged from inadequate to convincing for 30 variants identified on five type 2 diabetes genomic panels and by genome-wide association studies. Eight common variants were identified for general population use; evidence credibility based on published criteria was strong for two variants, moderate for two variants, and weak for four variants. TCF7L2 had the largest per-allele odds ratio of 1.39 (95% confidence interval 1.33–1.46). Models combining the best four, best eight, and all 30 variants used summary effect sizes, reported genotype frequencies, and assumed independent effects. Areas under the curve were 0.547, 0.551, and 0.570, respectively. In high-risk populations, per-allele odds ratios for TCF7L2 alone were similar to those of the general population. TCF7L2, in combination with other variants, yielded minimal improvement in risk reclassification. Evidence on TCF7L2 clinical validity was adequate. Three studies addressed the clinical utility of intervention effectiveness, stratified by TCF7L2 genotype; none found significant interactions. Clinical utility evidence was inadequate. In addition to analytic validity and clinical utility knowledge gaps, additional gaps were identified regarding how to inform, produce, and evaluate models combining multiple variants.Genet Med 2013:15(8):600–611     

Evaluating the association of common <Emphasis Type="Italic">PBX1</Emphasis>variants with type 2 diabetes

Background  

PBX1 is a biological candidate gene for type 2 diabetes at the 1q21-q24 susceptibility locus. The aim of this study was to evaluate the association of common PBX1 variants with type 2 diabetes in French Caucasian subjects.     

Founder mutations in <Emphasis Type="Italic">BRCA1/2</Emphasis> are not frequent in Canadian Ashkenazi Jewish men with prostate cancer

Background  

Relatives of BRCA1 and BRCA2 mutation carriers have long been proposed by epidemiological studies to have an increased risk of developing prostate cancer. In the Ashkenazi Jewish (AJ) population, the existence of 3 frequent founder mutations, 185delAG and 5382insC in BRCA1 and 6174delT in BRCA2 greatly facilitates screening for carriers.     

No association between variation in the <Emphasis Type="Italic">NR4A1</Emphasis> gene locus and metabolic traits in white subjects at increased risk for type 2 diabetes

Background  

The nuclear receptor NR4A1 is implicated in metabolic regulation in insulin-sensitive tissues, such as liver, adipose tissue, and skeletal muscle. Functional loss of NR4A1 results in insulin resistance and enhanced intramuscular and hepatic lipid content. Therefore, we investigated in a cohort of white European subjects at increased risk for type 2 diabetes whether genetic variation within the NR4A1 gene locus contributes to prediabetic phenotypes, such as insulin resistance, ectopic fat distribution, or β-cell dysfunction.     

Association analysis of <Emphasis Type="Italic">PON2</Emphasis> genetic variants with serum paraoxonase activity and systemic lupus erythematosus

Background  

Low serum paraoxonase (PON) activity is associated with the risk of coronary artery disease, diabetes and systemic lupus erythematosus (SLE). Our prior studies have shown that the PON1/rs662 (p.Gln192Arg), PON1/rs854560 (p.Leu55Met), PON3/rs17884563 and PON3/rs740264 SNPs (single nucleotide polymorphisms) significantly affect serum PON activity. Since PON1, PON2 and PON3 share high degree of structural and functional properties, in this study, we examined the role of PON2 genetic variation on serum PON activity, risk of SLE and SLE-related clinical manifestations in a Caucasian case-control sample.     

Common genetic variants of the ion channel transient receptor potential membrane melastatin 6 and 7 (TRPM6 and TRPM7), magnesium intake, and risk of type 2 diabetes in women

Background  

Ion channel transient receptor potential membrane melastatin 6 and 7 (TRPM6 and TRPM7) play a central role in magnesium homeostasis, which is critical for maintaining glucose and insulin metabolism. However, it is unclear whether common genetic variation in TRPM6 and TRPM7 contributes to risk of type 2 diabetes.