Scientists funded by the National Institutes of Health have identified a gene associated with narcolepsy, a disorder that causes disabling daytime sleepiness, sleep attacks, irresistible bouts of sleep that can strike at any time, and disturbed sleep at night. The gene has a known role in the immune system, which strongly suggests that autoimmunity, in which the immune system turns against the body's own tissues, plays an important role in the disorder.
"The link between narcolepsy and autoimmunity was proposed decades ago, but efforts to verify it have failed repeatedly. Current findings leave little doubt that autoimmunity plays a role," says Merrill Mitler, Ph.D., a program director with the National Institute of Neurological Disorders and Stroke (NINDS). The study was funded principally by NINDS, with additional support from the National Institute of Mental Health (NIMH), the National Heart, Lung and Blood Institute (NHLBI), and the National Institute of Allergy and Infectious Diseases (NIAID), all components of NIH.
The new study, which appears today in Nature Genetics, focused on narcolepsy with cataplexy a sudden loss of muscle tone that can cause a person to collapse, with or without falling asleep. About 1 in 2,000 Americans have narcolepsy-cataplexy. The symptoms of narcolepsy-cataplexy have been shown to result from the death of a small group of brain cells that normally regulate the sleep-wake cycle by releasing chemicals called hypocretins.
Genetic and environmental factors both clearly play a role in narcolepsy-cataplexy. Until now, the best evidence for autoimmunity as a cause of the disorder was the discovery that nearly everyone with the disorder has unique variants of a gene called HLA-DQB1*0602. This is one of the genes that encodes HLA proteins, which dot the surface of the body's cells and help the immune system identify foreign proteins. Some researchers theorize that the HLA variants found in peop
|Contact: Daniel Stimson|
NIH/National Institute of Neurological Disorders and Stroke