Genetic cause for type of childhood epilepsy identified

NEW YORK (Reuters Health) - Scientists have identified the mutated gene responsible for development of a type of epilepsy called childhood absence epilepsy, or CAE.

The condition is associated with frequent "absent" seizures where the patient's consciousness is impaired leaving the child staring blankly ahead not aware or responsive for up to 10 seconds at a time. An inherited disorder, CAE accounts for 10 to 12 percent of epilepsy in children under age 16. CAE often disappears in adulthood.

The scientists studied the DNA of 48 patients with CAE and discovered that 4 patients had a genetic mutation occurring in the GABA receptor, which binds to a neurotransmitter of the brain called GABA that inhibits the excitation of nerve cells. When this regulation is lost or reduced, seizures develop.

"We identified this genetic mutation in eight percent of study patients with CAE, which is significant," said Dr. Richard W. Olsen of the David Geffen School of Medicine at the University of California, Los Angeles, who was involved in the discovery, noted in a written statement.

The scientists also found that the mutated gene affected several generations of families. The mutated gene was absent in the DNA of 630 healthy people without CAE.

The scientists pinpointed the exact location of the mutation to a subunit gene of the GABA receptor called GABRB3. This location explains why CAE often remits in adulthood, they say, since this subunit is highly expressed in the fetus, but is reduced during later development.

The research, reported in the American Journal of Human Genetics, may provide insight into developing treatments and cures for this and other forms of epilepsy, the scientists say.

SOURCE: American Journal of Human Genetics, online May 29, 2008.