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

Abstract

Introduction: The vitamin D receptor (VDR) gene is a candidate for susceptibility to autoimmune disorders.\nAim of the work: To study the frequency of vitamin D deficiency in Egyptian systemic lupus erythematosus (SLE) patients and investigate the association of BsmI and FokI VDR gene polymorphisms with disease susceptibility, activity and damage.\nPatients 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 BsmI and FokI gene polymorphisms was performed by polymerase chain reaction and restriction fragment length polymorphism for only 34 patients and 16 controls.\nResults: 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 FokI and BsmI polymorphisms between patients and controls. There was a significant relation of FokI polymorphisms with serum vitamin D level (p = 0.002), SLEDAI (p = 0.021) and SLICC (p = 0.002). BsmI polymorphisms showed significant associations with neuropsychiatric damage, low complement, fever and mucosal ulcers.\nConclusions: VDR FokI 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.