Common variants of transcription factor 7-like 2 (TCF7L2) are associated with reduced insulin secretion in women with polycystic ovary syndrome

Abstract

Common variants of the transcription factor 7-like 2 (TCF7L2) gene were identified as one of the few genetic polymorphisms with powerful effects on the risk of type 2 diabetes (T2D). Given the genetic overlap between polycystic ovary syndrome (PCOS) and T2D, the present study was undertaken to investigate whether the TCF7L2 variants are also associated with PCOS. We analyzed single nucleotide polymorphisms (SNPs) rs11196218 and rs290487 of the TCF7L2 gene, which showed robust associations with T2D in Chinese population, in 430 PCOS patients and 360 control subjects by pyrosequencing, and also assessed the effect of genotype on clinical and biochemical traits in the PCOS group. We found no evidence for association between SNP rs11196218 and PCOS. The SNP rs290487 showed marginal differences in genotype frequencies between the PCOS and control group, with the minor C allele being the at-risk allele for PCOS. In PCOS women, the C allele carriers of rs290487 had higher levels of 2h blood glucose but lower insulinogenic index than noncarriers, suggesting impaired insulin secretion. Our data suggested that the TCF7L2 variants may confer an increased risk for early impairment of glucose homeostasis in PCOS.