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Last updated on April 20, 2014 at 5:20 EDT

Japanese Researchers Discover Narcolepsy Gene

September 29, 2008

Japanese scientists may have identified a gene variant linked to narcolepsy.

Narcolepsy is a condition marked by excessive daytime sleepiness, impaired vision and muscle weakness.

In the United States and Europe it occurs in 1 out of 2,500 individuals, but is at least 4 times more frequent in Japanese.

The researchers wrote in a paper published in Nature Genetics that the genomes, or DNA, of 222 narcoleptic Japanese were analyzed as well as 389 others who did not have that condition, and one gene variant occurred with significant frequency among those with narcolepsy.

“45 percent of those with narcolepsy had this gene variant compared to 30 percent of those without this condition,” said Professor Katsushi Tokunaga of the department of human genetics at the University of Tokyo said in a phone interview.

Tokunaga said identification of this gene variant could pave the way for experts to hunt for a treatment.

Researchers said the gene is located between the genes CPT1B and CHKB, both of which appear to be linked to the disorder. CPT1B controls an enzyme that regulates sleep, while CHKB is linked to the sleep-wake cycle.

The study took a further step to examine that same gene variant in 424 Koreans, 785 people of European descent and 184 African Americans.

It occurred with significant frequency among narcoleptic Koreans, but the association was not evident in the Europeans and African Americans.

Tokunaga said they have no idea why this gene variant occurs with such high frequency among (narcoleptic) Japanese and Koreans.

“It may be selection, or chance,” he said.

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