The Autoimmune thyroid diseases (AITDs) are among the most common endocrine disorders. Vitamin D as an immunomodulator and Vitamin D receptor (VDR) gene polymorphisms may be effective in AITDs pathogenesis. The aim of this study was to evaluate the vitamin D level and VDR BsmI and TaqI polymorphisms in Iranian Azeri Turkish patients with AITDs. This case-control study included 121 adults with AITDs and 117 non-AITDs controls. Serum level of 25-hydroxyvitamin D was measured by electrochemiluminescence (ECL) immunoassay. BsmI and TaqI polymorphisms were assessed by polymerase chain reaction fragment length polymorphism technique. The serum level of 25-hydroxyvitamin D in AITDs patients were lower than controls (P=0.03). The frequencies of TT, TC, CC, T and C genotypes/alleles at TaqI (rs731236) marker were 52.1%, 34.7%, 13.2% , 69.4% and 30.6% in AITDs and 44.4%, 41.9%, 13.7%, 65.4% and 34.6% in controls, respectively. The frequencies of AA, AG, GG, A and G genotypes/alleles at BsmI (rs1544410) marker were 14%, 64.5%, 21.5% , 46.3% and 53.7% in AITDs and 26.5%, 58.1%, 15.4%, 55.6% and 44.4% in controls, respectively. BsmI (rs1544410) GG+AG genotypes and G allele were more frequent among patients with Hashimoto compared with control group (86.6% vs. 73.5% (OR: 2.34, 95% CI: 1.16-4.70, P = 0.014) and 54.29% vs. 44.44% (OR: 1.48, 95% CI: 1.02-2.15, P = 0.038), respectively). Vitamin D status can be related to AITDs pathogenesis. BsmI (rs1544410) GG+AG genotypes and G allele may play an important role in the predisposition to Hashimoto.
