Certain versions of two genes show up in multiple sclerosis patients more often than in people without the disease, researchers report. Although these variations modify the usual roles of the genes only in subtle ways, scientists suspect that they are part of a network of dozens of gene variants that contribute to the disease.
Multiple sclerosis (MS) clearly has a hereditary component. A person whose identical twin has MS has a nearly one-in-three chance of developing it, compared with the average risk of about 1 in 1,000.
In the 1970s, scientists found that a specific version of a gene encoding human leukocyte antigen DRB1, an immune system protein, conferred a fourfold increase in the risk of MS. But the variant fell far short of accounting for all genetic risk associated with the disease. Two studies in the United States and one in Sweden now fill in more of the picture, indicati