Vitamin D status and CYP27B1‐1260 promoter polymorphism in Tunisian patients with systemic lupus erythematosus

AIM: An association between serum vitamin D (Vit D) levels and systemic lupus erythematosus (SLE) has been reported by several studies that suggested the involvement of genetically determined characteristics of enzymes of vitamin D metabolism. Our study aimed to evaluate the relationship between 25 hydroxyvitamin D (25[OH]D) level, the most representative metabolite of VitD status, and polymorphism of the cytochrome P450, CYP27B1 gene, which influence vitamin D metabolism, and serum levels, in SLE Tunisian patients. MATERIAL AND METHODS: A cross‐sectional study has been conducted in SLE patients (supplemented and not supplemented patients), matched to healthy controls by age and gender. The 25[OH]D serum level was measured by chemiluminescence assay and CYP27B1‐1260 genetic polymorphism was carried out using PCR‐RFLP methods. Statistical analysis was made using Shesis and SPSS.20 Software. RESULTS: Controls and Vit D not supplemented patients’ groups presented the highest percentage of hypovitaminosis D. A significant difference in the mean level of circulating 25[OH]D between Vit D supplemented SLE patients and controls was observed (23.91 ng/ml and 7.18 ng/ml, respectively p = 3.4 10(5)). Our results showed a correlation of high 25[OH]D level with complement component 3 levels and prednisolone drug. Moreover, the analysis of CYP27B1‐1260 polymorphism in SLE patients and controls revealed a nonsignificant allelic or genotypic association. CONCLUSION: Despite the sunny climate, the high prevalence of Vit D deficiency is common in Tunisia. This hypovitaminosis D feature may affect the Vit D levels in our SLE patients but a direct association with the disease or with the genetically determined features remains unclear. More studies are needed to establish thresholds and susceptibility genes according to the characteristics of each population.