RLS: Genes linked to restless legs

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Deseret News (Salt Lake City)

Genes linked to restless legs

by Mike Stobbe Associated Press

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 and not an

imaginary disorder.

New studies published this week in two top medical journals are

being called the first to identify specific genes responsible for

restless legs syndrome symptoms.

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., who was

diagnosed with it. So was her 43-year-old daughter.

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

the heavily advertised Requip, made by GlaxoKline PLC. Sales of

Requip hit about $500 million last year. Shaw takes the aqua-colored

pill and says it's the only thing that's helped her.

The first study looked at blood samples from more than 1,000

Icelanders and Americans, comparing the DNA of leg twitchers to the

DNA of people without the symptom. Scientists found a certain

variation in the human genome that, they say, probably accounts for

50 percent of restless legs cases.

They also found that the variation was associated with lower iron

levels, echoing -- but not explaining -- a relationship noted in

earlier research.

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.

More research is needed to develop a full explanation of the causes

of restless legs syndrome. The New England Journal study indicates

as many as 65 percent of adults carry the gene variation that can

lead to symptoms, said Dr. Rye, an Emory University

neurologist who was another co-author.

" People making the argument that this can't be very common -- that's

just gone, " said Rye, who himself has restless legs.

Others disagreed.

The syndrome is diagnosed through symptoms like periodic limb

movements in sleep, but lots of people may have limb movements

without having the condition, noted Dr. Woloshin, a Dartmouth

Medical School researcher who has argued the diagnosis is overhyped.

He argues that the best evidence puts the U.S. prevalence of

restless legs at under 3 percent, less than common estimates of 10

percent.