Rheumatoid Arthritis (RA) is an autoimmune inflammatory disease that leads to local and systemic arthritis and bone loss. Exploring genetic markers of candidate genes in osteoporosis and inflammatory cytokine genes could be a useful tool for the early identification of bone loss and fracture risk in RA patients. The target of this study is the evaluation and correlation between of Single Nucleotide Polymorphisms (SNPs) of Vitamin D Receptor (VDR) and possible effects on bone loss in RA.
40 Caucasian patients with RA (26 of them with a severe bone loss) and 40 healthy donors as control samples were genotyped for the VDR SNPs (called BsmI, ApaI, TaqI and FokI). The detection method is based on Restriction Fragment Length Polymorphism (RFLP).
Genotyping profile shown no difference between RA patients and controls. Only VDR-TaqI genotype (TT vs. tt) seem to influence the bone density in females, but not in males. The mean differences of Bone Mass Density (BMD) at the lumbar spine in RA women with the tt allele were 4.7% compared to 0.1% in women with the TT allele (p < 0.05).
The results of these studies support an association between specific VDR alleles and bone loss in RA. The TaqI t and BsmI B alleles were associated with an accelerated bone loss in RA, but not with a focal bone loss. These effects of VDR genotypes and vitamin D supplementation are not unexpected, given that the central pathological feature in RA is bone and joint destruction. The VDR SNPs genotyping should be a useful tool to screen early women RA patients with the bone loss.