Association between transforming growth factor-β1 T869C polymorphism and rheumatoid arthritis: a meta-analysis

Objective. The results of studies on association between TGF-beta 1 T869C polymorphism and susceptibility to RA are controversial. The absence of a replication of linkage might be due to different ethnicities. The aim of this study was to perform a preliminary investigation on the effect size of TGF-beta 1 T869C polymorphism on RA susceptibility through a meta-analysis. Methods. Case-control studies on the association of TGF-beta 1 T869C with RA were searched up to March 2009, and the genotype frequencies in the control group were found to be consistent with the Hardy-Weinberg equilibrium. The effect summary odds ratio (OR) and 95% CIs were obtained. Publication bias was tested by funnel plot with Egger's regression test, and heterogeneity was assessed. Results. Seven studies comprising 1122 cases and 1132 controls were included. Heterogeneity was observed (chi(2) = 17.16; P = 0.009). Under the random effects model, the common OR was 1.38 (95% Cl 0.95, 2.01; P = 0.09). In the subgroup meta-analysis, there was an association between TGF-beta 1 T869C polymorphism and RA in the people of Asian descent (OR = 1.93; 95% Cl 1.42, 2.62; P< 0.0001), but not in the people of non-Asian descent (OR = 0.88; 95% Cl 0.65, 1.19; P = 0.41). There was no evidence of publication bias according to Funnel plot and Egger's regression test (a = 4.778; P = 0.14). Conclusions. There was heterogeneity between studies, and no clear evidence of an association on a worldwide population was observed. Subgroup analysis results suggest that TGF-beta 1 T869C might play a role in RA susceptibility for Asians but not for non-Asians. Further studies are required for definite conclusions.