Polymorphism T→C of gene CYP17 promoter and polycystic ovary syndrome risk: a meta-analysis.

The T→C polymorphism of CYP17 gene has been inconsistently associated with polycystic ovary syndrome (PCOS) risk. We examined the association by performing a meta-analysis. Two investigators independently searched the Medline, Embase, CNKI, and Chinese Biomedicine Databases. Summary odds ratios (ORs) and 95% confidence intervals (95% CIs) for CYP17 polymorphism and PCOS were calculated in a fixed-effects model and a random-effects model when appropriate. The pooled ORs were performed for co-dominant model (CC vs. TT, TC vs. TT), dominant model (CC+TC vs. TT), and recessive model (CC vs. TC+TT). Subgroup analyses were performed by ethnicity, country, Hardy-Weinberg equilibrium (HWE) in controls and study sample size. This meta-analysis included 10 case-control studies, which included 1321 PCOS cases and 1017 controls. Overall, the variant genotypes (CC and TC) were not associated with PCOS risk, compared with the wild-type TT homozygote. Similarly, no associations were found in the dominant and recessive models. Stratified analyses by ethnicity/country also detected no significant association. However, limiting the analysis to the studies within HWE, a significantly increased risk was observed (TC vs. TT, OR=1.44, 95% CI=1.10-1.88; dominant model, OR=1.41, 95% CI=1.10-1.81). Moreover, when stratifying by study sample size, a significantly elevated risk was found among small sample studies (≤200 subjects), but not among large sample studies (> 200 subjects). This meta-analysis suggests that the CYP17 T/C polymorphism may be not associated with PCOS risk, while the observed increase in risk of PCOS may be due to small-study bias.