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

Abstract

BACKGROUND: Autoimmune hepatitis (AIH) and primary biliary cirrhosis (PBC) are two autoimmune diseases of unknown etiology. Genetic factors appear to be involved in the pathogenesis of both diseases. Vitamin D has been shown to exert multiple immunomodulatory effects, which acts through its own receptor (VDR). Polymorphisms of VDR had been implicated in several autoimmune diseases. In the present study, the association between Chinese patients with AIH, PBC and the polymorphisms in exon 2, intron 8 and exon 9 of vitamin D receptor genes was studied. METHODS: Four candidate gene loci were investigated in 49 patients with AIH, 58 patients with PBC, and 160 healthy controls. The VDR polymorphisms were assessed by FokI, BsmI, ApaI, and TaqI endonuclease digestion after specific polymerase chain reaction (PCR) amplification. RESULTS: The result show a significant difference in FokI polymorphism between AIH patients and controls (chi(2) = 5.47, P = 0.019), and a significant association in BsmI polymorphisms between PBC patients and controls (chi(2) = 6.52, P = 0.01). Furthermore the distribution of FokI, BsmI, ApaI, and TaqI gene types differed between Chinese healthy controls and Caucasian healthy controls. CONCLUSION: It is suggested that there is a genetic link of VDR polymorphisms to autoimmune liver diseases such as AIH and PBC in Chinese patients. Further studies are needed to elucidate the mechanisms by which VDR polymorphisms contribute to the lose of immune tolerance in autoimmune diseases.