An international team of researchers has identified the first gene associated with Restless Legs Syndrome (RLS), a common sleep disorder affecting tens of millions of people worldwide.
The findings will be published July 18 in the online edition of the New England Journal of Medicine and will appear in an upcoming printed edition of the journal. The work was led by scientists at Emory University and deCODE Genetics, Inc., in Reykjavik, Iceland.
Restless legs syndrome is a condition that produces an intense, often irresistible urge to move the legs and is a major cause of insomnia and sleep disruption. RLS affects approximately 10 percent of the U.S. population and about one percent of school-aged children. The discovery provides strong new evidence that RLS is a genuine syndrome, a fact which has recently been the subject of some debate.
"We now have concrete evidence that RLS is an authentic disorder with recognizable features and underlying biological basis," says David Rye, MD, PhD, professor of neurology at Emory University School of Medicine, director of the Emory Healthcare Program in Sleep, and one of the study's lead authors. "This is the most definitive link between genetics and RLS that has been reported to date. We have known for quite some time that the majority of RLS patients have a close family member with the disorder, and now we have found a gene which is clearly linked to RLS," says Dr. Rye.
The researchers report a population-attributable risk for RLS of at least 50 percent, meaning that were the gene variant not present, more than half of all RLS cases would disappear.
The variant is very common--nearly 65 percent of the population carries at least one copy of the variant. Two copies of the variant more than doubles one's risk of experiencing RLS.
According to Dr. Rye, having two copies does not ensure that one will develop symptoms of RLS. "There remain yet-to-be-identified medical, environmental or genetic factors that appear necessary to translate genetic susceptibility into RLS symptoms," he says.
RLS researchers have known for some time that anemia and low iron levels contribute to more severe RLS symptoms. The current study revealed the gene variant to be more common in Icelandic subjects deficient in iron.