Association of vitamin D receptor genetic variants with bone mineral density and inflammatory markers in rheumatoid arthritis

Background and aims: Vitamin D receptor (VDR) genetic variants are considered to have a role in the pathogenesis of rheumatoid arthritis (RA). This study examines an association of FokI, BsmI, ApaI and TaqI with RA, as well as with bone mineral density (RA with normal bone mineral density, RA-NBMD; RA with associated osteopenia, RA-OSTP; and RA with associated osteoporosis, RA-OP) and inflammatory markers. Materials and methods: VDR genetic variants were tested in 248 subjects using the PCR-RFLP method. Results: Significant differences were observed in the distribution of FokI genotypes between RA patients (p < 0.001), or subgroups (RA-NBMD, RA-OSTP, RA-OP) (p = 0.035, p = 0.02, p < 0.001, respectively) and controls. Prevalence of FokI f allele was significantly higher in RA group (p < 0.001) and subgroups (p = 0.003, p = 0.021, p < 0.001, respectively) compared to controls. An increased susceptibility to RA-OSTP was revealed in BsmI/ApaI Ba (AC) haplotype carriers (p = 0.012). A significantly higher erythrocyte sedimentation rate values were obtained in FokI FF compared to Ff + ff carriers (54.57 ± 23.73 vs. 22.83 ± 12.42; p < 0.001) within the RA-NBMD subgroup. Conclusion: The results of the study indicate an association of RA with FokI genetic variant and increased susceptibility to RA in f allele carriers, as well as to RA-OSTP in BsmI/ApaI Ba (AC) haplotype carriers.