C509T and T869C polymorphisms of transforming growth factor &bgr;1 and the risk of IgA nephropathy: a meta‐analysis

Background IgA nephropathy (IgAN) is the most common primary glomerular disease. Transforming growth factor &bgr;1 (TGF&bgr;1) plays an important role in pathogenesis of IgAN. Associations between the polymorphisms of TGF&bgr;1 gene and the risk of IgAN remained inconsistent. A meta‐analysis was conducted to investigate the association between polymorphisms in the TGF&bgr;1 gene and IgAN susceptibility. Methods Databases including Pubmed, EMBASE, ISI, et al. were searched to find relevant studies. Odds ratios (ORs) with 95% confidence intervals (CIs) were used to evaluate the strength of associations. Results Ten studies involving 1770 cases and 1953 controls were included. Significant association between C509T polymorphism and IgAN risk was observed (OR 1.42, 95% CI 1.12–1.81, P=0.0004; I2=0%) in Caucasians by the overdominant model (CT vs. CC + TT), but no significant association was found (P=0.200) in Asians by the dominant model (CC + CT vs. TT). Significant association between T869C polymorphism and IgAN susceptibility was found (OR 1.21, 95% CI 1.02–1.44, P=0.030) in overall populations by the dominant model (TT + TC vs. CC). Subgroup analysis found T allele of T869C polymorphism was associated with IgAN susceptibility in Caucasians (P=0.030), but not in Asians (P=0.290). Conclusion Both heterozygotes of C509T polymorphism and T allele of T869C polymorphism in TGF&bgr;1 were associated with the risk of IgAN in Caucasians, but not in Asians.