Association Study of Two Polymorphisms in Vitamin D Pathway with Multiple Sclerosis in the Moroccan Population

Multiple sclerosis (MS) is a demyelinating disease in which the insulating covers of nerve cells in the brain and spinal cord are damaged. It is the most common non-traumatic cause of neurologic disability in young and middle-aged adults and is characterized by a complex pathogenesis in which demyelinating lesions, axonal degeneration and gradual accumulation of sclerotic plaques are mainly responsible for this handicap.

Hypovitaminosis D is reported through the literature to be involved in autoimmune diseases such as multiple sclerosis (MS). In the last decade, numerous studies have investigated the association of single nucleotide polymorphisms (SNPs) with MS, including rs2248359 (CYP24A1) and rs703842 (CYP27B1) that are involved in vitamin D metabolic pathway. However, results were conflicting, probably due to ethnic differences between the studied populations.

In this context, the present study aimed to analyze the association between these two SNPs (rs2248359 (CYP24A1) and rs703842) and MS within the Moroccan population. rs2248359 and rs703842 were genotyped in 113 patients and 146 healthy controls. To assess their association with the disease risk, the authors compared the genotypic and allelic frequencies between the study groups. They also explored their possible influence on certain clinical features (age at onset, type, disability status and severity score) and with vitamin D3 serum level (DSL) by comparing mean values of these variables between the different genotypes. 

The results showed that no statistically significant differences in the distribution of both SNPs were found between patients and controls. A trend has emerged concerning the minor G allele of rs703842 which appears to have a protective effect on developing MS, but this result remained slightly below significance. Also, the two polymorphisms had no impact on the clinical features tested and the DSL. 

In conclusion, there was no convincing evidence that rs2248359 (CYP24A1) and rs703842 (CYP27B1) were associated with MS risk, some clinical features (age at onset, MS type, EDSS score and MSSS) or DSL within the Moroccan population. These findings require further confirmation from large independent studies.

Article by Asmae Skalli, et al, from Morocco.

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