RESUMO
BACKGROUND: Multiple sclerosis (MS) is an autoimmune demyelinating disease affecting mostly young adult females with multifactorial etiology. Recent studies suggested that adequate vitamin D levels may lower the risk of developing MS. OBJECTIVES: Our aim was to explore the relationship between vitamin D receptor (VDR) polymorphism, HLA-DR locus genotype, and serum vitamins D and A levels in the Lebanese population. METHODS: Fifty MS patients were recruited for this study. The control group consisted of 48 healthy and 51 patients with other neurological disorders (non-MS). Biochemical analysis included serum 25 hydroxyvitamin D (25OHD) and vitamin A. Molecular analysis targeted VDR genotypes (ApaI, TaqI and BsmI) and low resolution HLA typing for DRB1 locus. RESULTS: Healthy and non-MS groups had comparable parameters and were combined into one control group. No significant differences were found between MS and control groups for VDR genotypes. The frequency of HLA-DRB1*15 was significantly higher in MS patients (22%) compared to controls (8%) (p=0.018). Odds ratio for MS in the presence of DRB1*15 allele was 3.21 (p=0.018). Cosegregation with A (ApaI) and b (BsmI) alleles did not influence the risk for MS. 25OHD levels were significantly higher in MS patients compared to controls (p=0.002), due to more frequent oral supplementation (p=0.005). Vitamin A levels were comparable between the two groups. When all parameters were included in a logistic regression model adjusted for supplementation, only HLA-DRB1*15 (OR=3.42; p=0.027) contributed significantly to MS risk. CONCLUSION: There was no association between serum vitamin D or A or VDR genotypes and MS. HLA-DRB1*15 was the major factor imposing more than 3 folds greater risk for developing MS among Lebanese.