Association between vitamin-D receptor gene FokI polymorphism and Graves disease among Taiwanese Chinese

1,25(OH)(2)D-3, exerting its biological effects through the vitamin-D receptor (VDR), plays a role in the modulation of the human immune system. The aim of this study was to test for the presence of an association between VDR gene polymorphism and the susceptibility to Graves' disease (GD) for Taiwanese Chinese. Using a polymerase chain reaction (PCR)-based restriction analysis, we screened the VDR exon 2 start codon T/C (VDR-Fokl) polymorphism to determine the genotypes for 88 GD patients and 90 normal controls. From the genotype analysis, GD patients featured a greater proportion of the CC genotype (44.3%) and a smaller proportion of the TT genotype (12.5%) than was the case for normal controls (CC: 23.3% and TT: 28.9%: chi-souared test, P=0.003). The odds ratios (ORs) for the risk of the CC genotype's appearance compared with the corresponding values for the TT and TIC genotypes, for the GD patient group, were, 4.39 (95% confidence interval [CI]: 1.82-10.61) and 2.10 (95% CI: 1.06-4.18), respectively. With respect to the allelic analysis, we observed significantly increased C-allele (65.9%) and decreased T-allele (34.1%) frequencies among GD patients compared to normal controls (C: 47.2% and T: 52.8%; chi-squared test, P= 0.002). The OR for the risk of appearance of the C allele in the GD-patient group was 1.93 (95% CI: 1.27-2.95). In conclusion, the VDR-Fokl T/C polymorphism might be able to be used as a genetic marker to predict the likelihood of GD development.