The Influence of Vitamin D Receptor Gene Polymorphisms in Spondyloarthritis.

Spondyloarthritis (SpA) is an inflammatory rheumatic disease related to low bone mineral density. Because vitamin D plays an important role in bone metabolism and immune system modulation, the aim of this study was to evaluate the influence of polymorphisms in vitamin D receptor genes () in the development of SpA. In this case-control study, a total of 244 patients with SpA and 197 individuals with no SpA were included. Among the patients, 174 had ankylosing spondylitis (AS) and 66 had psoriatic arthritis (PsA). Genotyping of I (rs2228570 C > T), I (rs1544410 C > T), I (rs7975232 A > C), and I (rs731236 T > C) was performed using PCR-RFLP, while genotyping of was performed using PCR-SSP. Serum levels for hydroxy (OH) vitamin D and the clinical activity index of the disease (BASDAI) were also evaluated. SNPStats and OpenEpi software were used for statistical analysis. The I allele and I genotype were less frequent in PsA compared with controls. The I genotype was associated with a protecting factor for PsA in females, and I was associated with a protecting factor for the disease in positive patients. Notwithstanding, the I genotype was a risk factor for SpA and AS in males. The I genotype was associated with a better clinical activity in PsA. When considering the covariates, vitamin D sufficiency, and gender, the I genotype was associated with a risk factor in males with SpA and AS compared with females with this same genotype. In conclusion, the I rs7975232 polymorphism was associated with PsA, and the I rs2228570 polymorphism was associated with better clinical PsA activity. I and I were associated with SpA and AS when considering gender and vitamin D sufficiency.