Association of TCF7L2 gene polymorphisms with type 2 diabetes mellitus in Han Chinese population: a meta-analysis

Variants of transcription factor 7-like 2 (TCF7L2) gene have been reported to be associated with type 2 diabetes mellitus (T2DM), but the available data on this relationship are inconsistent in Han Chinese populations. A meta-analysis was performed to quantitatively analyze the association of TCF7L2 gene polymorphisms with T2DM using previous case-control studies in Chinese Han populations. Several electronic databases were searched for relevant articles up to May 2012. After data collection and gene loci selection, a meta-analysis was performed to assess heterogeneity, combine results and evaluate variations. Publication bias was examined by the Egger's linear regression test. Hardy-Weinberg equilibrium (HWE) test and by omitting one study at a time were employed for the sensitivity analysis. Eighteen studies from sixteen eligible papers were included in the meta-analysis. Ten eligible studies were analyzed for rs7903146, and eight were analyzed for rs290487. We found that the rs7903146 T allele was associated with an increased risk for T2DM under a dominant model, a co-dominant model and an allele contrast model, with an OR of 1.54 (1.32, 1.79), an OR of 1.53 (1.31, 1.79) and an OR of 1.52 (1.31, 1.76), respectively. The rs290487 C allele showed no significant overall association with T2DM, yielding ORs of 1.08 (0.88, 1.32) under a dominant model, with strong evidence of heterogeneity. Similar results were also obtained in other genetic models. Sensitivity analysis confirmed the reliability and stability of this meta-analysis. The accumulated evidence suggested that the rs7903146 T allele was associated with an increased risk for T2DM, but the rs290487 C allele is not associated with T2DM in the Chinese Han population. More well-designed large studies are required for the validation of this association.