Association of the CAG repeat polymorphisms in androgen receptor gene with polycystic ovary syndrome: A systemic review and meta-analysis

Background: Many studies have reported the associations of polymorphic CAG repeats in androgen receptor (AR) gene with PCOS risk, but with inconsistent results. So, the aim of present meta-analysis was to clarify such inconsistence, so as to provide more conclusive results. Methods: PubMed was searched for the eligible reports published until February 2012 without language limitation. The studies reporting the relationship between CAG repeat length and PCOS were selected for the meta-analysis according to the inclusion criteria. Two reviewers independently extracted the data and evaluated the study quality. Principal findings: As for the relationship between CAG repeat length and PCOS risk, the pooled results showed that the biallelic mean was not significantly different between PCOS and controls (SMD -0.03, 95% CI -0.16-0.10, P = 0.603), and that the ORs of PCOS were not demonstrated for the individuals with the biallelic mean less than median (OR 0.96, 95% CI 0.68-135, P = 0.794), with the short CAG allele (OR 0.94, 95% CI 0.80-1.10, P = 0.424), or with the X-weighted biallelic mean (OR 0.81, 95% CI 0.46-1.41, P = 0.447). Further, as for the relationship between CAG repeat length and T levels in PCOS patients, the biallelic mean was not significantly different between PCOS patients with high T and those with low T (SMD 0.79, 95% CI -0.12-1.70, P = 0.088), while the summary correlation r indicated that the CAG biallelic mean appeared to be positively associated with T levels in PCOS (r 0.20, 95% CI 0.11-030, p = 0.000). Conclusions: This meta-analysis demonstrates no evident association between the CAG length variations in AR gene and PCOS risk, while the CAG length appears to be positively associated with T levels in PCOS patients. (C) 2013 Elsevier B.V. All rights reserved.