Researchers report that vitamin D may interact with a specific genetic component called HLA-DRB1*1501 that is known to increase the risk of multiple sclerosis by three-fold.
“This study provides more direct support for the already strong epidemiological evidence implicating sunlight and vitamin D in the determination of MS risk. Given that a high frequency of vitamin D insufficiency in the general population has been observed, our data support the case for supplementation during critical time periods to reduce the prevalence of this devastating disease,” wrote lead author Sreeram Ramagopalan from the Wellcome Trust Centre for Human Genetics at the University of Oxford.
The results of the study are published in the open-access journal PLoS Genetics.
Previously, a study with 257 US military personnel with multiple sclerosis found that higher levels of vitamin D in the body may reduce the risk of developing MS by as much as 62 per cent, Harvard researchers reported in the Journal of the American Medical Association (Dec 2006, Vol. 296, pp. 2832-2838).
Multiple sclerosis (MS) is among the most common neurological diseases in young adults, affecting 350,000 individuals in the United States and 2 million worldwide. The disease is cause by a loss of nerve cells and the myelin sheath of the spinal cord that is vital to the transmission of signals around the body.
The Oxford-based researchers, in collaboration with researchers from the University of British Columbia in Canada, based their study on previous evidence that identified the Major Histocompatibility Complex (MHC) on chromosome 6, with variants to the gene HLA-DRB1, as the largest genetic effect for MS.
Using software to investigate the presence of a vitamin D response element (VDRE), which enables vitamin D to influence DNA, they looked at the HLA-DRB1*15 haplotype. Three hundred and twenty-two people with two copies of this haplotype, some with and some without MS. They were compared with 168 without this haplotype.
Dr Ramagopalan and co-workers found that vitamin D could switch gene on by binding to the VDRE in the region associated with HLA-DRB1*15.
“These studies imply direct interactions between HLA-DRB1, the main susceptibility locus for MS, and vitamin D, a strong candidate for mediating the environmental effect,” wrote the researchers.
Source: PLoS Genetics5(2): e1000369. doi:10.1371/journal.pgen.1000369“Expression of the multiple sclerosis-associated MHC class II allele HLA-DRB1*1501 is regulated by Vitamin D”Authors: S.V. Ramagopalan, N.J. Maugeri, L. Handunnetthi, Lincoln MR, Orton S-M, et al.