Public release date: 31-May-2012 [ | E-mail | Share ]

Contact: Holly Korschun hkorsch@emory.edu 404-727-3990 Emory University

Scientists have discovered that mutations in the gene BTBD9, which is linked with restless legs syndrome (RLS) in humans, disturb sleep in fruit flies. The mutant flies wake up more often during sleep periods, which resembles a key feature of human RLS.

The same mutations in BTBD9 also reduce levels of the neurotransmitter dopamine in the flies. Some kind of deficiency in dopamine signaling is thought to lie behind RLS in humans.

The results are published in the journal Current Biology.

"Flies and humans are distant from each other on the evolutionary tree, yet the same gene seems to be regulating a fundamental process in both organisms and affecting how soundly they sleep," says senior author Subhabrata Sanyal, PhD, assistant professor of cell biology at Emory University School of Medicine.

People with RLS experience unpleasant sensations in their legs and urges to move them, interfering with the ability to sleep. Genetics plays a major role in RLS, and most people with RLS have a close family member with the disorder. A variant in the BTBD9 gene accounts for about half of the risk for RLS in the population, according to multiple genetic studies (http://1.usa.gov/LqrO5L).

While medications exist to treat RLS, in some patients they are ineffective or have side effects. Researchers don't have a good understanding of what is going wrong in the nervous system in people affected by RLS, or what the BTBD9 gene does. Studying the fly version of BTBD9 could shed light on the basic biology and eventually lead to improved treatments for humans.

Postdoctoral fellow Amanda Freeman, the first author of the paper, examined flies' sleep behavior by putting individual flies into tubes with infrared sensors, which can detect when a fly moves across the middle of the tube. If a fly doesn't cross the beam for five minutes, it's considered asleep. She found that the BTBD9 mutant flies woke up more often during the night.

Disabling BTBD9 also makes flies more mobile while awake. Mutant flies confined in a tube move back and forth more often, leading Freeman and Sanyal to dub the mutant flies "wanderlust."

Read more:
Restless legs syndrome in fruit flies: Mutation in fly version of a human RLS gene disturbs sleep