association of esrα gene pvu ii t>c, xbai a>g and btgi g>a polymorphisms with knee osteoarthritis susceptibility: a systematic review and meta-analysis based on 22 case-control studies

Background: many studies have reported the association of estrogen receptor α gene (esrα) esrα pvuii t>c, xbai a>g and btgi g>a polymorphisms with knee osteoarthritis (koa) risk, but the results remained controversial. in order to drive a more precise estimation, the present systematic review and meta-analysis was performed to investigate the association between esrα polymorphisms and koa susceptibility. methods: eligible articles were identified by search of databases including pubmed, isi web of knowledge and google scholar up to march 1, 2017. data were extracted by two independent authors and pooled odds ratio (or) with 95% confidence interval (ci) was calculated. results: a total of 22 case-control studies in eleven publications with 6,575 koa cases and 7,459 controls were included in the meta-analysis. by pooling all the studies, either esrα pvuii t>c and xbai a>g polymorphisms was not associated with koa risk in the overall population. however, esrα btgi g>a was significantly associated with koa risk under all five genetic models. in the subgroup analysis by ethnicity, a significant association was observed between esrα pvuii t>c polymorphism and koa risk in asians under heterozygote model. in addition, significant association was found between esrα xbai a>g polymorphism and koa in caucasians under allelic, homozygote, dominant and recessive models. conclusion: the present meta-analysis suggests that esrα btgi g>a rather than esrα pvuii t>c and xbai a>g polymorphisms is associated with an increased koa risk in overall population. moreover, we have found that esrα pvuii t>c and xbai a>g polymorphisms associated with koa susceptibility by ethnicity backgrounds.