Vitamin D receptor polymorphisms are associated with increased susceptibility to primary biliary cirrhosis in Japanese and Italian populations

Background/Aims: Vitamin D receptor (VDR) agonists have recently been identified as potent immunomodulators capable of inhibiting Th1-mediated immune response, leading us to consider the hypothesis that functional VDR polymorphisms might contribute to enhanced risk for developing primary biliary cirrhosis (PBC), a Th1-mediated autoimmune disease. In the current study, we aimed at elucidating the genetic association of VDR polymorphisms with susceptibility to PBC in Japanese and Italian populations. Methods: We enrolled 334 PBC patients (195 Japanese and 139 Italians), as well as 334 age- and sex-matched controls (179 Japanese and 156 Italians). VDR genotyping was performed by PCR-RFLP, using BsmI, ApaI and TaqI endonucleases. Results: The genotype BB of BsmI polymorphism was significantly associated with PBC (OR = 1.80[95% CI; 1.19-2.73], p = 0.005). The association of the genotype BB was observed in Japanese (OR = 13.77, p = 0.001), and Italians (OR = 1.83, p = 0.019), respectively, although not significant in Italians after Bonferroni correction. The frequency of the B allele at the BsmI polymorphism was significantly higher in PBC patients (OR = 1.27[95% CI; 1.02-1.59], p = 0.040). Conclusions: The genotype 'BB' as well as 'B' allele at BsmI polymorphism of the VDR gene contribute to the risk of PBC development. (C) 2009 European Association for the Study of the Liver. Published by Elsevier B.V. All rights reserved.