Gene linked to narcolepsy identified

May 4th, 2009 - 5:15 pm ICT by ANI  

London, May 4 (ANI): Researchers have identified a gene linked to narcolepsy, a disorder that causes disabling daytime sleepiness, sleep attacks, irresistible bouts of sleep and disturbed sleep at night.

The gene is known for its 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 research team has found a gene called HLA-DQB1*0602.

This is one of the genes that encodes HLA proteins, which mark the surface of the body’s cells and help the immune system identify foreign proteins.

“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,” Nature quoted Dr Merrill Mitler, a program director with the National Institute of Neurological Disorders and Stroke (NINDS) as saying.

During the study, the researchers focused on narcolepsy with cataplexy - a sudden loss of muscle tone that can cause a person to collapse, with or without falling asleep.

This is due to the death of a small group of brain cells that normally regulate the sleep-wake cycle by releasing chemicals called hypocretins.

Some researchers believe that the HLA variants found in people with narcolepsy-cataplexy predispose them to an autoimmune reaction that destroys their hypocretin-producing cells.

In addition, people with narcolepsy-cataplexy are also more likely to have unique variants of the TCRA gene, which encodes a receptor protein on the surface of T cells.

The findings revealed that narcolepsy-cataplexy is linked to autoimmunity and involves T-cells. The research could lead to new approaches to prevention and treatment. One possibility may be preventing the disorder by stopping the effects of the autoimmune process.

“If we can define the changes in the T cell receptor associated with narcolepsy-cataplexy, we might be able to develop drugs that block the protein’s abnormal activity and prevent the onset of the disorder,” said Dr Emmanuel Mignot, director of the Center for Narcolepsy at Stanford University School of Medicine in Palo Alto, Calif., and a Howard Hughes Medical Institute investigator.

In people with the HLA variants that predispose to narcolepsy-cataplexy, there is about a 20-fold higher frequency of the disorder if variants in the TCRA gene are present.

The study appears in Nature Genetics. (ANI)

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