Vitamin D status and CYP27B 1‐1260 promoter polymorphism in Tunisian patients with systemic lupus erythematosus

Abstract 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.