Of 100K SNPs, one (rs7100927) was in moderate LD (r2 = 0.50) with TCF7L2 (rs7903146), and was associated with risk of diabetes (Cox p-value 0.007, additive hazard ratio for diabetes = 1.56) and with tFPG (GEE p-value 0.03).
However, the T allele (conferring higher risk of diabetes) at rs7903146 was associated with higher fasting proinsulin at baseline (P<0.001), higher baseline proinsulin:insulin ratio (p<0.0001) and increased proinsulin:insulin ratio over a median of 2.5 years of follow-up (P = 0.003).
Resequencing and analysis of variation in the TCF7L2 gene in African Americans suggests that SNP rs7903146 is the causal diabetes susceptibility variant.
We studied 120 individuals of whom one-half were homozygous for the diabetes-associated allele TT at rs7903146 and one-half were homozygous for the protective allele CC.
We investigated the association between the TCF7L2 rs7903146 polymorphism and incident IFG defined as fasting serum glucose levels of 100-125 mg/dL (5.6-6.9 mmol/L) in 1377 African American and 5152 Caucasian participants without diabetes and IFG at intake who participated in the Atherosclerosis Risk in Communities (ARIC) Study from 1987 to 1989 and were followed for 9 years.
Using four TCF7L2 single nucleotide polymorphisms (SNPs; including the two most associated in the previous study), we conducted a case-control study in 2,158 type 2 diabetic subjects and 2,574 control subjects and a family-based association analysis in 388 parent-offspring trios all from the U.K. All SNPs showed powerful associations with diabetes in the case-control analysis, with strongest effects at rs7903146 (allele-wise relative risk 1.36 [95% CI 1.24-1.48], P = 1.3 x 10(-11)).
TCF7L2 rs7903146 C>T polymorphism is associated with diabetes in the general population but its independent impact on cardiovascular disease is debated.
The minor allele frequency for rs7903146 was different between TCP and FCPD patients carrying the N34S SPINK1 variant but did not reach statistical significance (OR = 1.59, 95% CI = 0.93-2.70, P = 0.09), while, TCF7L2variant showed a statistically significant association between TCP and FCPD patients carrying the 26V allele (OR = 1.69, 95% CI = 1.11-2.56, P = 0.013).
For four candidate SNPs (rs780094, rs10830963, rs7903146, and rs4607517), the strength of association between genotype and glucose was significantly (P-interaction<0.05) different in those with and without prevalent diabetes, and for all five fasting glucose candidate SNPs (rs780094, rs10830963, rs560887, rs4607517, and rs13266634) the association with measured fasting glucose was more significant in the smaller sample without prevalent diabetes than in the larger combined sample of those with and without diabetes.
Analysis of TCF7L2 rs7903146 in normal controls and diabetics with or without nephropathy demonstrated that the 'T' allele is associated with both diabetes (p = 0.049) and DN (p = 0.024), but this association is not independent of T2DM.
Over an average follow-up period of 5.43 years, participants with the rs7903146 T allele or variants in the same LD block, but not those with the rs290481 G allele, were more likely to progress to diabetes (hazard ratio = 2.61, 95% confidence interval, 1.27-5.39, P = 0.009) than were non-carriers.
In this study, we aimed to confirm the effect of the TCF7L2 polymorphism rs7903146 on diabetes risk in a Brazilian population and to assess the use of this genetic marker in improving diabetes risk prediction in the general population.
We hypothesised that both a parental history of diabetes and TCF7L2 rs7903146 polymorphism, which increases susceptibility to diabetes because of impaired beta cell function, are associated with incident hypertension.
Diabetes-associated variation (T allele at rs7903146) in TCF7L2 may impair the ability of hyperglycemia to suppress glucagon (45 ± 2 vs. 47 ± 2 vs. 60 ± 5 ng/L for CC, CT, and TT, respectively, P = 0.02).
In subjects without known diabetes (n=961) recruited from the Chennai Urban Rural Epidemiology Study (CURES), OGTT, IDRS, and genotyping of rs12255372 (G/T) and rs7903146(C/T) of TCF7L2 polymorphisms were done.
Our study provides the first significant evidence of association between the TCF7L2 rs7903146 polymorphism and type 2 diabetes risk in a large African American population and also demonstrates that the diabetes risk conveyed by the rs7903146 risk allele is substantially increased in the context of some metabolic risk factors for type 2 diabetes.
Over an average period of three years, participants with the risk-conferring TT genotype at rs7903146 were more likely to have progression from impaired glucose tolerance to diabetes than were CC homozygotes (hazard ratio, 1.55; 95 percent confidence interval, 1.20 to 2.01; P<0.001).
Diabetes disease stage was marginally significantly associated with the frequency of the T variant at rs12255372 (p=0.057; adjusted p=0.017) but not at rs7903146 (p=0.5; adjusted p=0.2).
We genotyped rs7903146 in 608 individuals without diabetes and recorded biochemical data before and after <i>1</i>) one dose of glipizide (5 mg) on visit 1 and <i>2</i>) a 75-g oral glucose tolerance test (OGTT) performed after administration of metformin 500 mg twice daily over 2 days.
Concerned with predisposition for diabetes mellitus in obese children, we tested if risk genotypes TC and TT of rs7903146 are more common in obese children with increased homeostasis model assessment insulin resistance index (HOMA-IR) compared to obese controls with normal HOMA-IR.