Vitamin D receptor gene polymorphism in patients with sarcoidosis

The active form of vitamin D, 1,25-dihydroxyvitamin D(3), is known to be produced at sites of granulomatous reactions in sarcoidosis. 1, 25-dihydroxyvitamin D(3) has multiple immunomodulatory effects, and acts as a promoter of multinucleated giant cell formation. Polymorphism of the vitamin D receptor (VDR) gene has recently been shown to be related to bone mineral density, and also associated with hyperparathyroidism and risk of prostatic carcinoma. Considering that this might affect sarcoidosis, we investigated polymorphism of the VDR gene in 101 patients with sarcoidosis and 105 healthy control subjects. Their genotypes were determined using polymerase chain reaction (PCR) and restriction fragment length polymorphism. In the patients with sarcoidosis, the BB, Bb, and bb genotypes accounted for 1.0%, 37.6%, and 61.4%, whereas in healthy control subjects the figures were 1.0%, 20.0%, and 79.0%, respectively. The difference in the genotype distribution between healthy control subjects and sarcoidosis patients was significant (p < 0.05) with the frequency of the B allele being elevated (p < 0.05). From the result, we suggest that in VDR gene polymorphism the B allele might be a genetic risk factor for sarcoidosis.