Associations between estrogen receptor-beta polymorphisms and endometriosis risk: a meta-analysis

BACKGROUND Many epidemiological studies have suggested an association between estrogen receptor-beta (ER-β) polymorphisms with endometriosis risk. However, the results of these studies have been inconsistent. In the present study, we performed a meta-analysis to clarify the associations between the ER-β rs4986938 and rs1256049 polymorphisms and endometriosis risk. METHODS Eligible publications were retrieved from the PubMed, ISI Web of Science, and several Chinese language databases. Pooled odds ratios (ORs) with 95% confidence intervals (CIs) were calculated using a random or fixed effect model. RESULTS A total of eight studies (1100 cases/1485 controls) for the rs4986938 polymorphism and four studies (353 cases/450 controls) for the rs1256049 polymorphism were included in this meta-analysis. Regarding the rs4986938 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, study sample size, endometriosis-associated infertility, and stage of endometriosis, a significantly increased risk was observed among mixed populations (dominant model, OR=2.03, 95% CI=1.56-2.64) and among cases with endometriosis-associated infertility (dominant model, OR=1.83, 95% CI=1.26-2.67). Regarding the rs1256049 polymorphism, no obvious associations were found for all genetic models in the overall population. Subgroup analyses by ethnicity and study sample size revealed that only one study of a mixed population with small sample size showed an increased risk of endometriosis. No publication bias was found in the present study. CONCLUSIONS The results of this meta-analysis suggest that the ER-β rs4986938 and rs1256049 polymorphisms may not be associated with endometriosis risk, while the observed increased risk of endometriosis-associated infertility may be due to bias by the inclusion of small-scale studies. VIRTUAL SLIDES The virtual slide(s) for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/13000_2014_184.