Two studies, both involving people from Iceland and the US, found that the disorder that causes people to impulsively move their legs, particularly during the night, can be genetic. It can also be related to low iron in the body.
In a statement, study co-author Dr. Kari Stefansson said, "This discovery demonstrates the power of genetics not only for uncovering the biological causes of disease, but also for defining diseases such as RLS and establishing them as medical conditions."
There are several medications available to treat RLS. One, called Requip and made by GlaxoSmithKline PLC, is the most popular with $500 million in sales last year.
About half of the 1,000 participants in the first study showed a variation in the human genome. Blood samples of those who said they experienced symptoms were compared to those who did not claim to have symptoms.
Co-author and Emory University neurologist Dr. David Rye said more research should be done to find the cause of RLS, especially since about 65 percent of adults carry the gene found to cause symptoms, according to the study.
"People making the argument that this can't be very common -- that's just gone," He said.
