Restless Leg Syndrome: Two Studies Prove Genetic Basis of the Disease

I have been reading about Restless Legs Syndrome (RLS) here on Associated content. I was really impressed by the article of Charlene Collins about her suffering with this RLS.

Today, I was so happy when I read a couple of scientific papers that may help people such as Charlene that suffer every day and night from this syndrome.

RLS is a poorly understood illness. Until now it is believed to be a neurological issue. A National Institutes of Health (NIH) consensus panel established in 2003 the RLS criteria for diagnosis and its epidemiology. From that study the conditions for RLS were summarized as: (a) an urge to move the limbs with or without sensations, (b) worsening at rest, (c) improvement with activity, and (d) worsening in the evening or night.

Two studies appeared independently in prestigious scientific journals: one in the New England Journal of Medicine (NEJM) and the other in the journal Nature Genetics (see sources bellow).

The first study was carried out by a team of scientists from Emory University (Atlanta, GA) and a company incorporated in Iceland (deCODE Genetics). Around 1200 people participated in the study (1000 Icelanders and 188 Americans). The study took more than four years. A genome-wide association (GWA) study and two replication studies were conducted.

Scientists in this study examined a total of 300,000 bits of DNA (that means 300,000 of single nucleotide polymorphisms, called "snips") to find differences between people having RLS or not. The results of the study are significant. They prove that the RLS is for real and not an imaginary twitching of the legs (sometimes called "Jimmy Legs") as it was popularized by one episode of famous TV sitcom "Seinfield.

A significant link between a common variant of a gene called BTBD9 (which is located on chromosome 6p21.2) and RLS and periodic limb movements in sleep was discovered. This gene snip was first found in one Icelandic sample and replicated in two further samples: another from Iceland and another from the US.

The other study, published in Nature Genetics, was carried out by a consrtium of scientists from three countries: Germany, Austria, and Canada. The team examined the genes of over 4,300 German and Canadian subjects, of which at least 1,500 had RLS. The same gene, BTBD9, was found to be related to RLS such as it is realted in Icelanders and Americans.

It seems that nationality is not a factor in RLS but instead it is a seriously biological issue unrelated to fenotypical differences in humans.

In addition to the biological and genetic basis for RLS it was found that iron defficiency may be related to RLS symptoms worsening. Both studies did not evaluated what medication is needed or treatments that can be followed to alleviate RLS symptoms.

Sources:

Stefansson et al. 2007. A Genetic Risk Factor for Periodic Limb Movements in Sleep New England Journal of Medicine. Published online July 18, 2007. URL: http://content.nejm.org/cgi/content/full/NEJMoa072743v1

Winkelmann et al,. 2007. Genome-wide association study of restless legs syndrome identifies common variants in three genomic regions. Nature Genetics Published online: 18 July 2007. URL: http://www.nature.com/ng/journal/vaop/ncurrent/abs/ng2099.html

Allen et al. 2003. Restless legs syndrome: diagnostic criteria, special considerations, and epidemiology. A report from the restless legs syndrome diagnosis and epidemiology workshop at the National Institutes of Health.". Sleep Med 4 (2): 101-19.

Charlene Collins. Restless Legs Syndrome-Associated Content. URL: http://www.associatedcontent.com/article/292362/restless_legs_syndrome.html