Aug. 10, 2011 -- The number of genes linked to multiple sclerosis (MS) is now up to 57, following a large international study of more than 9,000 people with the disease.
The genetic mapping of the disorder, a chronic disease affecting the central nervous system, is moving at a swift pace, says researcher Alastair Compston, MD, PhD, professor of neurology at the University of Cambridge, U.K.
"We have moved from three [genes linked] in 2007 to 57 now," he tells WebMD.
The new research confirms 23 genes that were suspected to be linked with MS and adds another 34, he says. Of that 34, 29 are definite and five are probable. The new findings also provide support for the belief that MS begins with an abnormal response of the body's immune system, he says.
"If we look at the genes which are implicated by these 57 hits, they tell a remarkably coherent story, because 80% of them are all genes which drive the body's immune response,” Compston says. “They are immunological genes."
Experts have debated whether MS is a degenerative disease that triggers immune system inflammation or whether the process is the reverse. "Based on this research, the inflammation comes first," Compston says.
For MS patients, he tells WebMD, the findings suggest that treatments that do not focus on immunological origins don't make much sense.
About 400,000 Americans have MS, according to the National Multiple Sclerosis Society. The disease attacks the sheath that insulates nerves, called myelin.
The severity of symptoms varies greatly. Some people have mild symptoms, such as numbness in the limbs. Others have much more severe symptoms, such as balance problems, loss of vision, and paralysis.
In 1970, Compston says, one gene was identified with a susceptibility to MS. "In 2007, we were up to three."
Only in the last three or four years, Compston says, have his group of researchers and others inched the number up past 20, and now, up to 57.
Genes Linked to MS: New Findings
The new study, a genome-wise association study, involved 9,772 MS patients and a comparison group of 17,376 people who did not have MS. The patients and the comparison group came from 15 countries, including the U.S. In all, 23 research groups collaborated.
Most experts now believe that MS involves an abnormal immune system response. They also think environmental factors play a role. Among the possible environmental factors are infectious causes and migration patterns. People born in one area that has a high risk of MS and move as a young child to another area with lower risk have been found to acquire a lower risk, for instance.