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Restless leg syndrome may have genetic roots

Similar findings in separate studies

ATLANTA -- Scientists have linked certain genes to restless legs syndrome, suggesting the twitching condition described as "jimmy legs" in a "Seinfeld" episode is biologically based.

New studies published this week in two top medical journals are being called the first to identify specific genes responsible for the symptoms of restless legs syndrome, or RLS.

Research in the New England Journal of Medicine linked a common gene variation to nighttime leg-twitching. It involved people in Iceland and the United States.

A second study in Nature Genetics identified the same gene variation and two others in Germans and Canadians with restless legs syndrome.

"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," said Dr. Kari Stefansson in a prepared statement.

Stefansson is a prominent Icelandic scientist who co authored the New England Journal study.

Restless legs syndrome is a neurological condition characterized by an irresistible urge to move the legs. Sufferers say it often hits at night, preventing them from sleeping. "It feels like something crawling inside your legs, biting on you," said Betty Shaw, a 68-year-old florist in Covington, Ga.

The condition gained cultural status through an oft-quoted episode of the sitcom "Seinfeld," in which the character Kramer is disturbed that his girlfriend has "the jimmy legs" and kicks in bed.

It's commonly treated with two government-approved drugs, including Requip, made by GlaxoSmithKline PLC.

The first study looked at blood samples from more than 1,000 Icelanders and Americans, comparing the DNA of leg twitchers with the DNA of people without the symptoms. Scientists found a certain variation in the human genome that, they said, probably accounts for 50 percent of cases.

The second study compared the DNA of 400 people with a family history of the syndrome with the DNA of 1,600 who did not. It found variations in three areas of the genome that each were responsible for a 50 percent increase in the risk for the syndrome.

Dr. Steven Woloshin, a Dartmouth Medical School researcher, said the diagnosis is overhyped.

The new research doesn't pin down what the condition is, who has it, or what medication is needed, he wrote in an e-mail.