First new MS genes in 20 years
After decades of dead ends, scientists have identified two genes that may raise the risk of multiple sclerosis, lending insight into the causes of this debilitating neurological disease.
The findings, released in two medical journals, represent the first genes conclusively linked to multiple sclerosis, or MS, in more than 20 years, experts say.
In a large-scale study appearing online in the New England Journal of Medicine, teams of international researchers scanned the human genome of more than 12,000 people for MS risk factors.
The study uncovered two new gene suspects, both thought to play a role in autoimmune disease.
Until now, the only genetic link identified with MS was the major histocompatibility complex, or MHC, a large cluster of genes essential to the immune system.
Neither of the newly discovered genes appears to be as instrumental to developing the disease as MHC, but the research is important because it lends insight into other genetic factors that raise a person's risk of multiple sclerosis.
"Having this genetic road map will be of incredible importance in developing new therapies," says Professor David Hafler of Harvard Medical School, who worked on the genome study.
The role of one of the gene suspects in MS, a variant of the interleukin-7 or IL-7 receptor, was confirmed in two papers published online in the journal Nature Genetics.
The gene helps control the activity of regulatory T cells, which suppress the activation of the body's immune system.
"This discovery brings us into a whole new pathway that could have a very important role in understanding the fundamental mechanisms that trigger MS," says Professor Stephen Hauser at University of California San Francisco, who worked on the studies in both journals.
While the studies used different methods, they both pointed the finger at the IL-7 receptor gene.
One of the Nature Genetics studies, led by Dr Jonathan Haines of Vanderbilt University Medical Center examined variants in three genes suspected to have a role in the disease.
It found variants in IL-7 receptors were consistently more common in MS patients than in healthy people.
Researchers observed a similar association in a separate study in the journal by Professor Jan Hillert of the Karolinska Institute in Stockholm and colleagues, who looked at a large collection of people from Scandinavia.
The other gene identified by the whole genome scan, the IL-2 receptor, has been linked to two other autoimmune diseases: type 1 diabetes and autoimmune thyroid disease.
"The story here is the commonality of autoimmune disease," Hafler says.
Researchers believe both environmental and genetic factors play a role in the development of MS, a disease of the central nervous system that attacks and destroys insulation along nerve fibres.
MS affects more than 2.5 million people globally who have a range of symptoms from mild muscle weakness to complete paralysis.