Association Study of Transcription Factor 7-like 2 (TCF7L2) Gene Polymorphisms and Haplotypes with Type 2 Diabetes in the South-West of Iran

Type 2 diabetes mellitus (T2DM), one of the costliest chronic diseases of our time, is a multifactorial and heterogenic disease with a complex etiology. Among all the T2DM related genes, the SNPs of the transcription factor 7-like 2 (TCF7L2) gene have been recognized as the strongest genetic risk factors for T2DM in different ethnic groups by several studies. The aim of this study was to investigate the possible association between TCF7L2 gene polymorphisms (rs290487, rs11196205, rs7903146, and rs12255372) and the risk of T2DM in a population from Khuzestan province, South-West of Iran.

In this case-control association study, we studied 146 patients with T2DM and 146 healthy subjects. Genotyping for rs290487 and rs11196205 were done by Tetra-Primer ARMS-PCR and genotyping for rs7903146 and rs12255372 were carried out using PCR-RFLP. Statistical analyses were carried out using SPSS v.25.

For rs290487 polymorphism, TT and TC genotypes were not observed in patients and controls, and all of the subjects showed only CC genotype. The C allele of rs11196205 polymorphism was associated with T2DM (OR = 1.393, 95% CI = 1.005-1.932, p-value = 0.046). Two other studied polymorphisms, rs7903146 and rs12255372, had no significant differences in the genotype and allele frequencies between the two groups. Three-variant haplotypes of TCF7L2 gene were analyzed using the PHASE software. There was no significant difference between control group and case group for haplotype distribution.

Our results suggest that there is a significant association between rs11196205 polymorphism and T2DM, but no association is observed between the three other polymorphisms (rs290487, rs7903146, and rs12255372) with T2DM in the studied population. Moreover, no risk haplotype is reported in our population.