Japanese researchers found a genetic variant which could be responsible for narcolepsy. Narcolepsy is a neurological disorder that causes sudden sleeping episodes even after normal nighttime rest. People suffering from this disorder suffer from "sleep attacks" without any warning during any normal activity. This is an uncommon condition. Approximately one out of 600 Japanese suffer from narcolepsy. Some people in addition to this disorder experience "cataplexy", where strong emotions such as anger, surprise, or laughter can trigger an instant loss of muscle strength, which, in some cases, can cause collapse. The present study was done by a team of scientists led by Tokyo University Prof. Katsushi Tokunaga.  

Earlier it was believed that this disorder is triggered either by genetics or environment, including mental stress. It was also believed that cause of this disorder revolves around shortage of a chemical called hypocretin which sends signals to the brain about sleeping and waking up.  

In the recent study, researchers studied the genetic code of hundreds of volunteers with and without narcolepsy. Researchers extensively examined the DNA of normal subjects and narcolepsy patients by comparing 500,000 single nucleotide polymorphisms, or SNPs. SNP is a DNA sequence variation between members of a species.  

During the research, researchers discovered a genetically mutated fragment of chromosome 22 which increased subjects' vulnerability to the disease by 1.8 times. Researchers also discovered that the mutation causes a malfunction of the gene CPT1B, which is linked to sleep. Researchers also found that a link between the genetic mutation and narcolepsy was also found in South Koreans.
 
The present research can help in finding the cause of the condition and to help development of a cure. The researchers believed that while current treatments focused on dealing with the symptoms of narcolepsy, their genetic findings could help point the way to understanding the underlying mechanisms responsible - in particular what was causing the shortage of hypocretin.  

They concluded that it is hoped that the discovery of the present susceptibility gene(s) might contribute to the establishment of novel therapeutic approaches.