By John Lauerman
Bloomberg News
Monday, July 30, 2007

Genes newly linked to an increased risk of multiple sclerosis have bolstered understanding of the incurable nerve disorder and may lead to added treatments, researchers said.

A screen of the human genome implicated three genes in MS and hinted that a dozen more may be involved. The findings, reported online in the New England Journal of Medicine and the journal Nature Genetics, offer new hope to the 2.5 million people worldwide with MS, a disabling disease that progressively damages the nervous system and can lead to paralysis, researchers said.

"We suspect there will be dozens, perhaps hundreds of gene variations associated with MS," David Hafler, a Harvard Medical School neurologist at Brigham and Women's Hospital in Boston, said in an interview Friday.

Earlier research found that two of the three genes were probably implicated in MS. Yesterday's reports strengthened those links, added a new one and suggested that a dozen more genes may be involved, said Hafler, who wrote the New England Journal report with researchers from Britain, Canada, and multiple U.S. institutions.

In the New England Journal study, research groups combined their efforts to screen 12,360 people with and without MS to determine which genetic variations occurred most often in people with the disease. Overall, researchers involved in three separate, though related, studies screened more than 20,000 people using new tools, called "snip chips," that detect tiny variations within the genome.

The results describe the first genes conclusively linked with MS since the 1970s, said Ursula Utz, a program director for the National Institute of Neurological Disorders and Stroke, part of the National Institutes of Health.

The New England Journal study and the two papers in Nature Genetics for the first time linked variations in a gene called IL7R with MS. Researchers were surprised because IL7R was not considered as strong a candidate as another gene, called IL2R, that was also implicated by the research.

The IL7R gene makes a molecule that reacts with interleukin-7, a chemical the body makes to slow down the immune response. A variation of the gene raises levels of the receptor within the cell body, rather than in its outer layer. That version is linked with higher MS risk, said Jonathan Haines, a Vanderbilt University Medical Center geneticist who led one of the studies in Nature Genetics.

It is unclear what triggers MS, though researchers believe it is spurred by both genetic and environmental factors.