Vitamin D receptor gene polymorphism as possible risk factor in rheumatoid arthritis and rheumatoid related osteoporosis.

OBJECTIVE: To study the role of VDR polymorphisms as risk factor for RA and osteoporosis, and whether osteoporosis complicating RA is due to RA or VDR polymorphisms. METHODS: VDR gene polymorphisms ApaI, TaqI, BsmI and FokI were typed by RFLP for 128 RA patients, 30 postmenopausal osteoporotic females and 150 healthy controls. RESULTS: Significant differences were found between patients and healthy controls in the frequency of BsmI and TaqI (Pc<0.05) but no significant associations were found for FokI and ApaI polymorphisms except for aa genotype (Pc<0.001). Titers of RF were higher with aa and bb genotypes. Anti-CCP and CRP levels were higher with aa genotype and more bone loss was associated with Bb genotype. Ff genotype frequency was higher in RA patients with osteoporosis than those without osteoporosis. CONCLUSIONS: The ApaI, BsmI and TaqI polymorphisms may be a susceptibility risk factors for RA and the Ff genotype may be responsible for development of osteoporosis in RA Egyptian patients. However, the present study needs to be replicated in a large number of patients from allover the Egypt and also in multi-ethnic populations.