Gene mutation causes febrile seizures and severe epilepsy in infants

Mutations in the SCN9A sodium channel gene are a cause of febrile seizures and contribute to a severe form of epilepsy in infants 6 months and younger, report researchers from the University of Utah, University of Antwerp, and University of Washington. The findings, published in the 18 September issue of the open-access journal PLoS Genetics, suggest that infants with Dravet syndrome, a type of epilepsy that often begins with fever-induced (febrile) seizures, could be tested for the SCN9A gene mutation to determine whether or not they should receive sodium channel blockers to treat their seizures.

Febrile seizures are the most common form of early childhood seizures and occur in about 1 in 20 children in North America. Most infants outgrow them, but in some cases, the seizures continue into adulthood.

Epilepsy, a disorder of many types of seizures, affects nearly 3 million people in the United States, with approximately 200,000 new cases reported each year. Patients with Dravet syndrome have febrile and other seizures severe enough to adversely affect mental and social development.

The researchers identified the SCN9A mutation after studying a large family with a history of febrile seizures. The mutation was introduced into mouse models, which were observed to have significantly lower thresholds for seizures than mice without the mutation. The researchers confirmed their findings by expanding the study to include non-related patients from the United States and Europe. Now the fifth gene discovered to cause febrile seizures, SCN9A previously had not been suspected in seizures or epilepsy, according to first author Nanda A. Singh.

"This new gene gives us a much needed novel target for developing more effective drugs to treat those children with debilitating seizures," Singh said.

(Source: American Society of Nephrology: PLoS Genetics: September 2009)