Association of GSTP1 −313A/G polymorphisms and endometriosis risk: a meta-analysis of case–control studies

Abstract Objectives In view of the controversies surrounding the association of glutathione S-transferases (GST) P1 with endometriosis, a meta-analysis of GSTP1 −313A/G polymorphism with endometriosis risk was performed. Study design The relevant studies were identified through a search of PubMed, Excerpta Medica Database (Embase), Elsevier Science Direct and Chinese Biomedical Literature Database (CBM) until March 2013. The association between GSTP1 −313A/G polymorphism and endometriosis risk was pooled by odds ratios (ORs) together with their 95% confidence intervals (95% CIs). Results A total of eight case–control studies were eventually identified. We found that GSTP1-313A/G polymorphism was not associated with endometriosis risk in the overall population (A vs. G: OR = 1.02, 95% CI = 0.97–1.07, P = 0.511; AA vs. GG: OR = 1.02, 95% CI = 0.98–1.06, P = 0.359; GA vs. GG: OR = 1.03, 95% CI = 0.98–1.08, P = 0.299; AA vs. GA/GG: OR = 1.01, 95% CI = 0.96–1.07, P = 0.621; AA/GA vs. GG: OR = 1.00, 95% CI = 0.97–1.03, P = 0.972). In the sub-group analysis based on ethnicity, a significant association was found in Caucasians under the recessive model (AA vs. GA/GG: OR = 1.28, 95% CI = 1.08–1.53, P = 0.006). Conclusions GSTP1 −313A/G polymorphism may not be associated with endometriosis risk, while the observed increase in risk of endometriosis may be due to small-study bias. Considering the limited sample size and ethnicity included in our meta-analysis, an updated meta-analysis will be urgently needed when further larger and well-designed studies are published.