Study links gene variant and vitamin D to MS risk

LONDON Thu Feb 5, 2009 9:39am EST

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LONDON (Reuters) - A certain genetic variant combined with a vitamin D deficiency when young may increase a person's chances of developing multiple sclerosis later in life, British researchers said Thursday.

The finding suggests that giving vitamin D supplements to pregnant women and young children could reduce the risk of getting the disease, they reported in the journal PLoS Genetics.

It also bolsters previous evidence implicating the so-called "sunshine" vitamin in the autoimmune disease, which affects 2.5 million people worldwide.

"Vitamin D is a safe and relatively cheap supplement with substantial potential health benefits," Sreeram Ramagopalan, a University of Oxford researcher, who worked on the study, said in a statement.

"There is accumulating evidence that it can reduce the risk of developing cancer and offer protection from other autoimmune diseases."

Multiple sclerosis is a disease of the nervous system caused by damage to the myelin sheath that protects nerve cells. It can cause symptoms ranging from vague tingling to blindness and paralysis.

Vitamin D, made when skin is exposed to sunlight and found in fatty fish like salmon, is added to milk and other foods in many countries. Evidence suggests it helps lower blood pressure, reduce inflammation and boost the immune system.

"We have known for a long time that genes and environment determine multiple sclerosis risk," George Ebers, a researcher at the University of Oxford, who worked on the study, said in a statement.

"Here we show that the main environmental risk candidate -- vitamin D -- and the main gene region are directly linked and interact.

The researchers found that proteins activated by vitamin D bind to a particular DNA sequence lying next to the DRB1 variant, which in effect switches the gene on. Too little vitamin D may cause the gene to malfunction, they said.

This means for people who carry the variant, a vitamin D deficiency during early life might impair the body's ability to delete T-cells which go on to attack the body and lead to a loss of myelin on the nerve fibers, the researchers said.

"In people with the DRB1 variant associated with multiple sclerosis, it seems that vitamin D may play a critical role," Julian Knight, a University of Oxford researcher, who worked on the study.

"If too little of the vitamin is available, the gene may not function properly."

(Reporting by Michael Kahn; Editing by Charles Dick)