Vitamin D receptor gene polymorphisms influence susceptibility to type 1 diabetes mellitus in the Taiwanese population

OBJECTIVE Vitamin D and its receptor have been suggested to play a role in the pathogenesis of type 1 diabetes mellitus, We have therefore studied the influence of vitamin D receptor (VDR) gene polymorphisms on susceptibility to type 1 diabetes, and rates of glutamic acid decarboxylase (GAD(65)) autoantibody and islet cell autoantibody (ICA(512)) positivity. SUBJECTS AND MEASUREMENTS One hundred and fifty-seven type 1 diabetic patients and 248 unrelated normal controls were recruited for this study. Genomic DNA was extracted from peripheral blood leucocytes, All type 1 diabetic patients and controls were genotyped using polymerase chain reaction (PCR) and restriction fragment length polymorphism (RFLP), for three restriction sites in the VDR gene, Bsml, Apal and Taql, The chi(2) test was used to compare the frequency of the VDR gene polymorphisms in patients and normal controls. The association of VDR gene polymorphisms in type 1 diabetes with the presence of GAD(65) and ICA(512) autoantibodies were also examined using the chi(2) test. RESULTS The allele frequency of the Bsml and Apal polymorphisms, but not Taql polymorphism, differed between patients and controls (Bsml P=0.015; Apal P=0.018; Taql P=0.266). However, after correction for the three different polymorphisms tested, only the Bsml was significant (pc = 0.045). CONCLUSIONS Vitamin D receptor gene polymorphisms were associated with type 1 diabetes in a Taiwanese population. However, functional studies are needed to establish the role of the vitamin D receptor in the pathogenesis of type 1 diabetes mellitus.