Study confirms narcolepsy is an autoimmune disorder

Cell Colony

Researchers at Stanford claim they have confirmed a long-standing hypothesis: narcolepsy is an autoimmune disorder.

 

Narcolepsy is a disorder which causes severe sleepiness in the daytime, poor sleep at night, and a sudden loss of muscle strength (cataplexy). In the early 1990s, Dr. Emmanuel Mignot of Stanford University found that those afflicted with narcolepsy lack proper levels of the wakefulness hormone hypocretin. It was later found that this is due to the fact that they are missing the cells in the brain which produce the hormone.

 

Because of the missing cells, Mignot believed that narcolepsy may be an autoimmune disorder, based on literature that showed a tentative link between narcolepsy and a certain type of human leukocyte antigen (HLA) gene. “The immune system uses HLAs to differentiate between "self" cells and foreign cells (and attacks those presented as foreign), and most autoimmune diseases are associated with variants of HLA. In recent studies, more than 90 percent of narcolepsy patients were shown to carry one such variant.”  [EurekAlert] In an autoimmune disease, immune cells turn against the body, against the self, and can inflict serious harm to internal organs, joints, and the brain.

 

In order to prove that narcolepsy truly was an autoimmune disorder, Mignot had to show abnormal behavior from the immune cells in those afflicted by the disease. To find the proof, Mignot embarked on an intense study of the human genome, using genetic material from over 1,800 patients worldwide.  Whole-genome scans allow for side-by-side comparison of the genes found in humans.  By using objective computer software, scientists can spot changes in the genome of those suffering from a disease.  This sort of analysis usually does not yield an exact answer, but it can point researchers in the right direction.

 

Mignot found a variation in T cells (important players in the immune system) in those suffering from narcolepsy, offering for the first time proof that the disorder is autoimmune.  How exactly the T cells and variation of HLA cause the drop in hypocretin-producing cells is not yet known, but will be the focus of further studies.  

 

The scientists hope these findings will help other researchers who are hunting for answers in other autoimmune diseases such as rheumatoid arthritis or type 1 diabetes.  "I'm sure immunologists are going to be very excited," said Mignot of the findings. "If we can work out what happens specifically in patients with narcolepsy, we'll be able to better understand the role of T cells in other autoimmune diseases that are more complicated and difficult to detect." [EurekAlert]

 

This research is published in the current issue of Nature Genetics.

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