Narcolepsy Caused by Autoimmune Disease
Narcolepsy affects one in 2000 individuals. Stanford researchers have found that narcolepsy is caused by a single immune cell. Autoimmune disease has long been suspected as the cause of narcolepsy, and the new study demonstrates for the first time that a variation of a T-cell gene causes narcolepsy.
Howard Hughes Medical Institute investigator, Emmanuel Mignot, MD, PhD says, "For a long time, people have suspected narcolepsy had something to do with the immune system - that it was killing cells that produce hypocretin” - a protein that regulates sleep and wakefulness. Until now there was no direct proof that narcolepsy is caused by an autoimmune disease.
Dr. Mignot first identified hypocretin as missing in people with narcolepsy ten years ago, and later findings that narcoleptics lack brain cells that produce hypocretin. Mignot now found out narcolepsy is an autoimmune disease.
Researchers analyzed hundreds of thousands of genetic variations to find the T-cell gene variance that causes narcolepsy. T-cells play an important role in immunity. The scientist isolated 800 individuals who had narcolepsy from a group of 1800 with the same HLA (human leukocyte antigen) gene variant. When they looked further, they found those 800 people had the specific gene variation producing narcolepsy, leading to the findings that narcolepsy occurs because of autoimmunity.
Dr. Mignot says, “Our discovery clearly shows narcolepsy is an autoimmune disease.” HLA is important for immune function as are T-cells. Dr. Mignot speculates that HLA and T-cells may interact to produce the autoimmune dysfunction responsible for narcolepsy, by killing hypocretin cells, but plans more studies. Further understanding may lead to early identification of individuals predisposed to narcolepsy.
The findings that narcolepsy is an autoimmune disease should help researchers find ways to treat other autoimmune diseases, such as multiple sclerosis and juvenile diabetes.