THURSDAY, Feb. 5 (HealthDay News) -- A direct interaction between vitamin D and a common genetic variant may affect a person's risk of multiple sclerosis, according to British and Canadian researchers who also said that vitamin D deficiency while in the womb and early in life may increase the risk of MS later in life.

Both genetic and environmental factors play a role in MS, a neurological condition that affects 2.5 million people worldwide. Vitamin D is a major environmental factor, and the largest genetic effect comes from the region on chromosome six containing a gene variant called DRB1*1501 and from adjacent DNA sequences.

In the general population, about one in 1,000 people will develop MS. But that increases to about one in 300 among people who have a single copy of the DRB1*1501 and about one in 100 among people with two copies of the variant.

The study found that proteins activated by vitamin D in the body bind to a particular DNA sequence lying next to the DRB1*1501 variant, which causes the gene to switch on.

The study was published in the Feb. 6 edition of PLoS Genetics.

"In people with the DRB1 variant associated with MS, it seems that vitamin D may play a critical role. If too little of the vitamin is available, the gene may not function properly," study co-author Julian Knight said in a journal news release.

The researchers believe that vitamin D deficiency in mothers or even in a previous generation may lead to altered expression of DRB1*1501 in offspring.

"Our study implies that taking vitamin D supplements during pregnancy and the early years may reduce the risk of child developing MS in later life," lead author Dr. Sreeram Ramagopalan said in the news release. "Vitamin D is a safe and relatively cheap supplement with substantial potential health benefits. There is accumulating evidence that it can reduce the risk of developing cancer and offer protection from other autoimmune diseases."

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