London, Sept 29 : By finding a genetic variant linked to a much higher risk of the sleep disorder narcolepsy, Japanese researchers may unravel the mystery behind the disorder, according to a new study.
University of Tokyo researchers, who led the study, say that their findings may highlight narcolepsy's causes.
Narcolepsy is an uncommon and distressing condition, in which the patients can suffer "sleep attacks" without any warning during any normal activity. Its sufferers may experience "cataplexy", where strong emotions such as anger, surprise, or laughter can lead to an instant loss of muscle strength, which, in some cases, can cause collapse.
The researchers are hoping that the discovery of the present susceptibility gene(s) might lead to the establishment of novel therapeutic approaches
While the causes behind narcolepsy are still unclear, some scientists think that it is may be caused due to a shortage of a chemical called hypocretin which sends signals to the brain about sleeping and waking up.
Scientists have not ruled out the possibility that the condition could be hereditary in nature.
Thus, the researchers are looking for the genetic differences, which may be involved. They looked at the genetic code of hundreds of volunteers, some with narcolepsy, some without, to look for differences.
They found a variant, which was linked to a 79 percent higher chance of narcolepsy in Japanese people, and a 40 percent increased chance in other ethnic groups.
The variant was found close to two genes, CPT1B, and CHKB, which have already been pointed out for causing the disorder, because of their role in regulating sleep.
According to the researchers, while current treatments focused on dealing with the symptoms of narcolepsy, their genetic finding may help point the way to understanding the underlying mechanisms responsible. Particularly it could reveal the reason behind the shortage of hypocretin.
"We hope that the discovery of the present susceptibility gene(s) might contribute to the establishment of novel therapeutic approaches," the BBC quoted the researchers as saying.
UK sleep specialist Dr Renata Riha, from Edinburgh's Royal Infirmary, claimed that the variant was unlikely to provide the sole explanation for narcolepsy in patients.
A research article describing the study has been published in the journal Nature Genetics.