Estrogen receptor-alpha gene PvuII (T/C) and XbaI (A/G) polymorphisms and endometriosis risk: A meta-analysis

Estrogen receptor-alpha (ER-alpha) polymorphisms have been hypothesized to be associated with the risk of endometriosis (EMT) development by many epidemiological studies, however, the available results were conflicting. To derive a more precise estimation of association between the ER-alpha PvuII (T/C) and XbaI (A/G) polymorphisms and risk of EMT, we performed a meta-analysis. Summary odds ratios (ORs) and 95% confidence intervals (95% CIs) for ER-alpha polymorphisms and EMT were calculated in a fixed-effects model and a random-effects model when appropriate. This meta-analysis included 20 case-control studies with 1752 cases and 1742 controls for PvuII polymorphism and 15 case-control studies with 1349 cases and 1411 controls for Xbal polymorphism. For PvuII T/C polymorphism, no obvious associations were found for all genetic models when all studies were pooled into the meta-analysis. In the subgroup analyses by ethnicity, country, HWE in controls and study sample size, a significantly increased risk was observed among Caucasians (recessive model, OR=2.56, 95% CI=1.06-6.16) and among studies without the HWE (recessive model, OR=1.85, 95% CI=120-2.84). For XbaI A/G polymorphism. also no obvious associations were found for all genetic models. In the subgroup analyses by ethnicity, country. HWE in controls and study sample size, still no obvious associations were found. No publication bias was found in the present study. This meta-analysis suggests that ER-alpha gene PvuII (T/C) and Xbal (A/G) polymorphisms may not be associated with EMT risk, while the observed increase in risk of EMT may be due to small-study bias. (C) 2012 Elsevier B.V. All rights reserved.