Transcription factor 7-like 2 (TCF7L2) gene polymorphisms are strong predictors of type 2 diabetes among nonobese diabetics in the Turkish population

Background/aim: Type 2 diabetes (T2D) is a multifactorial disease, determined by environmental and genetic factors. Currently, the transcription factor 7-like 2 (TCF7L2) gene shows the strongest association with T2D. In this study, we investigated whether TCF7L2 gene polymorphisms are associated with T2D in a Turkish population. Materials and methods: Using PCR-RFLP and PCR-SSCP, we genotyped six intronic polymorphisms in the TCF7L2 gene, commonly associated with T2D, in 169 individuals with diabetes and 119 healthy controls. Results: We found that rs7903146 C → T substitution in intron 3 (OR: 1.9, P = 0.005) and rs12255372 G → T substitution in intron 4 (OR: 2.1, P = 0.002) were significantly associated with T2D while other SNPs were not associated (P > 0.05). We determined no association between TCF7L2 gene polymorphisms and fasting glucose, fasting insulin, HbA1c, or HOMA-IR levels (P > 0.05), except for rs7903146 C → T substitution, which was significantly associated with the fasting glucose level (P = 0.003). Conclusion: Our results indicate that, in the Turkish population, the T allele of the rs7903146 (C → T) and rs12255372 (G → T) polymorphisms in the TCF7L2 gene is an independent risk factor for the development of T2D.