Vitamin D receptor polymorphisms and 25-hydroxyvitamin D in a group of Sicilian multiple sclerosis patients

Multiple sclerosis (MS) is an auto-immune disease whose etiology remains controversial. Both genetic and environmental factors are thought to be involved in the risk of developing the disease. The purpose of our study was to assess the association of Vitamin D receptor (VDR) polymorphisms with MS and to investigate the interaction of these polymorphisms with vitamin D levels. A total of 179 Sicilian subjects, including 104 MS patients and 75 healthy controls, were studied. The most common VDR polymorphisms (Fok-I, Bsm-I, Taq-I and Apa-I) were genotyped by polymerase chain reaction (PCR) followed by restriction fragment length polymorphism (RFLP) analyses in both groups and serum 25-hydroxyvitamin D [25(OH)D] levels were determined in MS patients by high-performance liquid chromatography (HPLC). The distribution of genotype and allele frequencies of the four VDR polymorphisms did not differ significantly between MS patients and healthy controls, and were unrelated to the forms and the course of MS. Low serum levels of 25(OH)D were observed in MS patients but no association was observed between VDR and 25(OH)D levels except for Fok-I. Moreover, MS patients with FF and Ff genotype had a significantly lower serum levels of 25(OH)D compared with ff carriers (P < 0.05 FF vs Ff and Ff vs ff). Our findings showed no association between VDR polymorphisms and risk of MS. Interestingly, F allele could confer a genetic predisposition to lower 25(OH)D levels.