Lack of association between vitamin D receptor gene ApaI, BsmI, and TaqI polymorphisms and primary biliary cirrhosis risk: a meta-analysis

Previous studies have reported the association between vitamin D receptor (VDR) polymorphisms and the risk of primary biliary cirrhosis (PBC), although these results remain controversial. The aim of this meta-analysis was to evaluate the association of three polymorphisms in VDR with PBC risk. The relevant studies were identified through an electronic database search carried out in September 2013. The crude odds ratio (OR) and 95 % confidence interval (CI) were calculated to assess the association between VDR polymorphisms and PBC risk. Six eligible studies which met our selection criteria were included. Overall, the ApaI, BsmI, and TaqI polymorphisms in the VDR gene were not associated with PBC risk (ApaI A vs a OR = 1.132, 95 % CI = 0.870-1.472, p = 0.355; BsmI B vs b OR = 1.148, 95 % CI = 0.697-1.891, p = 0.589; TaqI t vs T OR = 1.1432, 95 % CI = 0.709-1.841, p = 0.584). Furthermore, in subgroup analysis by ethnicity for the ApaI, BsmI, and TaqI polymorphisms, there were no significant results in either Caucasians or Asians under the allele contrast and recessive and dominant models. This meta-analysis indicated that VDR polymorphisms were not a risk factor for PBC. Larger and more carefully designed studies are needed to verify our results.