Association between the (TAAAA)n SHBG polymorphism and PCOS: a systematic review and meta-analysis

Human sex hormone-binding globulin (SHBG) is a specific plasma transport glycoprotein for sex steroid hormones, and serum SHBG levels were decreased in polycystic ovary syndrome (PCOS) patients. To clarify the conflicting data in the literature concerning the association between PCOS and the (TAAAA)n SHBG polymorphism, and influence of the (TAAAA)n SHBG polymorphism on serum SHBG levels of PCOS patients, a systematic review and meta-analysis was performed in this study. Literature search was conducted through PubMed, EMBASE and China National Knowledge Infrastructure. Five studies were included, representing 1595 individuals. No statistically significant associations were found between the (TAAAA)n SHBG allele and genotype with PCOS risk. Moreover, because the influence of the (TAAAA)n SHBG polymorphism on serum SHBG levels of PCOS patients in studies included in our review was investigated in different way to classify the alleles, we were unable to perform a meta-analysis and hence could not draw any conclusions. In conclusion, this study indicates that there is insufficient evidence to demonstrate a conclusive association between the (TAAAA)n SHBG polymorphism with the risk of PCOS, which needs to be further confirmed by further studies.