Vitamin D Receptor () Genetic Variants: Relationship of Genotypes with Expression and Clinical Disease Activity in Systemic Lupus Erythematosus Patients.

Vitamin D (VD) deficiency is more frequent in systemic lupus erythematosus (SLE) patients than in control subjects (CS); genetic variants in the VD receptor () could contribute to the clinical disease activity. This study was aimed to determine the association of the variants (rs2228570), (rs1544410), (rs7975232), and (rs731236) with susceptibility to the disease, VD status, mRNA expression, and clinical disease activity in SLE patients. A cross-sectional study was conducted in 194 SLE and 196 CS Mexican women. Immunoassays quantified serum calcidiol and calcitriol. Genotyping was performed by allelic discrimination assays and mRNA expression by qPCR. The variant was not in linkage disequilibrium with , and variants. SLE patient carriers of the TT genotype showed higher clinical disease activity scores. Notably, the mRNA expression was higher in SLE patients vs. CS, in active vs. inactive SLE patients, and in participants of both study groups with vitamin D deficiency, higher calcitriol levels, and TT genotype carriers. In conclusion, the TT genotype was related to high expression and clinical disease activity in systemic lupus erythematosus patients.