Genetic association of vitamin D receptor polymorphisms with primary biliary cirrhosis and autoimmune hepatitis

Autoimmune hepatitis (AIH) and primary biliary cirrhosis (PBC) are immune-mediated chronic inflammatory diseases of the liver of unknown etiology. Genetic factors appear to be involved in the pathogenesis of both diseases. 1,25-Dihydroxyvitamin D-3 has been implicated as an immunomodulator, which acts through its own receptor (VDR). Polymorphisms of the VDR have been linked to a variety of autoimmune diseases. In this study VDR polymorphisms were analyzed in 123 patients with AIH, 74 patients with PBC, and 214 controls. VDR polymorphisms were assessed by BsmI, TaqI, ApaI, and Fok endonuclease digestion after specific polymerase chain reaction (PCR) amplification. We found a significant association between the BsmI polymorphisms in PBC patients in comparison with controls (chi (2) = 9.49, P = .009). Furthermore we detected a significant association of the Fok polymorphims in AIH patients in comparison to controls (chi (2) = 9.71, P = .008) indicating a genetic link of VDR polymorphisms to autoimmune liver diseases such as PBC and AM in German patients. These findings contribute to the knowledge of the complex events determining immunologic tolerance in the liver. Further studies are needed to elucidate the mechanisms by which the vitamin D receptor contributes to the development of autoimmune diseases.