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Mouse Model Sheds Light on ARX Infantile Spasms

Interneuron loss of ARX leads to type of epilepsy with some features of infantile spasms

TUESDAY, June 15 (HealthDay News) -- A mouse model of pediatric epilepsy with features of infantile spasms, along with new findings in families with gene mutations linked to infantile spasms, could change the counseling given to families of children with such mutations, according to research published in the June issue of Brain.

Eric Marsh, M.D., of the Children's Hospital of Philadelphia, and colleagues developed mice in which the aristaless-related homeobox gene (ARX) was selectively deleted from interneurons. In humans, ARX has been associated with infantile spasm syndrome.

The researchers found that male mice showed different types of seizures starting early in life, including seizures that resembled infantile spasms. Roughly half of the female mice carrying a lone mutant ARX allele also had seizures. The authors also discuss 25 heterozygous females with ARX mutations from 16 families, including 14 mothers of affected males and nine other female relatives. They further note that all 14 mothers of male probands had normal development and cognition, while most other relatives of these probands had seizures or cognitive deficits.

"Our results significantly change the counseling regarding female fetuses or children with severe mutations of ARX. Further studies in these mice will permit a better understanding of the multiple roles of interneurons in establishing normal network properties in the developing brain. Understanding the pathophysiologic mechanism as to how these mice develop an infantile spasms-like phenotype may facilitate the development of more specific therapies against this malignant developmental epilepsy," the authors conclude.

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