Clinical significance of vitamin D deficiency and receptor gene polymorphism in systemic lupus erythematosus patients

Introduction The vitamin D receptor (VDR) gene is a candidate for susceptibility to autoimmune disorders. Aim of the work To study the frequency of vitamin D deficiency in Egyptian systemic lupus erythematosus (SLE) patients and investigate the association of Bsm I and Fok I VDR gene polymorphisms with disease susceptibility, activity and damage. Patients and methods Forty-five SLE patients and 40 controls were enrolled. SLE Disease Activity Index (SLEDAI) and Systemic Lupus International Collaborating Clinics (SLICC) damage index were assessed for the patients. Serum vitamin D levels were measured in all subjects. Genotyping for the VDR Bsm I and Fok I gene polymorphisms was performed by polymerase chain reaction and restriction fragment length polymorphism for only 34 patients and 16 controls. Results The mean age of SLE patients was 28.8 ± 7.9 years and disease duration 11.3 ± 9.8 years. Vitamin D level was significantly lower in patients than control (p < 0.001) and significantly correlated with C3 and C4 levels (p < 0.001) and inversely with SLEDAI (p < 0.001), SLICC (p = 0.005), anti-ds DNA (p < 0.001) and ESR (p = 0.011). There were no significant differences in genotype and allelic frequencies of Fok I and Bsm I polymorphisms between patients and controls. There was a significant relation of Fok I polymorphisms with serum vitamin D level (p = 0.002), SLEDAI (p = 0.021) and SLICC (p = 0.002). Bsm I polymorphisms showed significant associations with neuropsychiatric damage, low complement, fever and mucosal ulcers. Conclusions VDR Fok I polymorphism in SLE patients is significantly related to low vitamin D level in SLE patients and both are associated with increasing disease activity and damage denoting important implications in this disease.