A GENE that causes a rare form of epilepsy, often mistaken for a sleep disorder, has been found by Australian researchers. The discovery, reported at the ANZAAS meeting, may eventually lead to improved diagnosis and treatment for the more common forms of epilepsy.
While other genes have been found for neurological and mental disorders that are accompanied by epilepsy, 鈥渘o other gene has been isolated for a pure form of epilepsy鈥�, said Grant Sutherland of the Women鈥檚 and Children鈥檚 Hospital in Adelaide, who led the research.
The gene, which sits on the long arm of chromosome 20, codes for a receptor on the surface of nerve cells, called CHRNA4. This receptor binds to one of the neuro-transmitter chemicals that brain cells use to communicate with one another. Late last year, researchers in France and Germany linked a mutation in the same gene to another form of epilepsy (快猫短视频, Science, 24/31 December 1994). But they subsequently withdrew their claim, as their 鈥渕utation鈥� turned out to be an aberration in their DNA sequencing. One researcher, Ortrud Steinlein of the University of Bonn, has worked with both teams.
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Sutherland鈥檚 team pinpointed the gene in a single Australian family spanning six generations, including 27 people with a condition called autosomal dominant nocturnal frontal lobe epilepsy (ADNFLE). This rare disorder, identified two years ago by Sam Berkovic, a neurologist at the Austin Hospital in Melbourne, strikes during sleep or drowsiness. 鈥淢ost likely this form of epilepsy has often been misdiagnosed as a sleep disorder,鈥� Sutherland told the ANZAAS meeting.
Two other families, one in Britain and another in Canada, are also believed to be suffering from ADNFLE. But so far, said Sutherland, the gene responsible for the disorder in these families has not been isolated.
Sutherland said he thought it likely that other, more common forms of epilepsy are also due in part to abnormalities in CHRNA4 or related neurotransmitter receptors. 鈥淭he gene we have found to be abnormal is a member of a large family of genes,鈥� he said. 鈥淚t may be that other similar genes are also involved in epilepsy.鈥�
Sutherland and his colleagues describe their results in full in this month鈥檚 issue of Nature Genetics.