It was observed that carrying the GG genotype (OR = 1.8; CI = 1.1–3.0; p = 0.01) in rs10877012 in CYP27B1 was associated with higher susceptibility to hypovitaminosis D. On the other hand, for the susceptibility of RA, carrying the CT genotype (OR = 1.9; CI = 1.2–2.9; p < 0.01) in rs731236 VDR was associated with higher susceptibility to the disease. The gene discussed is CYP27B1; the disease is rheumatoid arthritis.