Vitamin D receptor gene polymorphisms and type 1 diabetes mellitus in a Korean population

Background Vitamin D receptor (VDR) has been suggested to play a role in the pathogenesis of type 1 diabetes mellitus (T1DM). There has been no case-control study examining the association between VDR polymorphisms and T1DM among Korean subjects with a low incidence of T1DM. Methods Eighty-one T1DM patients and 113 unrelated healthy controls with no history of DM or other autoimmune diseases were investigated at either Pusan National University Children's Hospital or Korea University Anam Hospital between March 2009 and September 2013. Polymerase chain reaction-restriction fragment length polymorphism was utilized to genotype single nucleotide substitutions at TaqI, BsmI, and ApaI alleles. Results All frequencies in T1DM and control subjects were in Hardy-Weinberg equilibrium, although ApaI in controls and TaqI in T1DM showed relatively weak equilibrium. TaqI and BsmI differences were significant (P = 0.045 and P = 0.012, respectively) after applying Bonferroni correction. The TT genotype carrier frequency among controls was higher than among the T1DM patients (P = 0.015; OR, 2.98; 95%CI: 1.19-7.42). T allele frequency was higher among controls than T1DM patients (P = 0.019; OR, 2.78; 95%CI: 1.15-6.72). The frequency of bb genotype carriers among controls was higher than among T1DM patients (P = 0.004; OR, 4.13; 95%CI: 1.4-12.10). The frequency of the b allele among controls was higher than that among T1DM patients (P = 0.016; OR, 3.20; 95%CI: 1.19-8.60). Conclusions T and b TaqI and BsmI alleles are protective against T1DM in Korean subjects.