Single gene mutation behind catastrophic epilepsy

Washington, July 8 (ANI): Researchers at Baylor College of Medicine have found a mutation in a single gene to be responsible for catastrophic epilepsy - characterized by severe muscle spasms, persistent seizures, mental retardation and sometimes autism.

Dr. Jeffrey Noebels, professor of neurology, neuroscience and molecular and human genetics at BCM and director of the Blue Bird Circle Developmental Neurogenetics Laboratory at BCM, said that the team replicated the defect in mice, developing a mouse model of the disease that could help researchers figure out effective treatments for and new approaches to curing the disease.

"While many genes underlying various forms of childhood epilepsy have been identified in the past decade, most cause a disorder of 'pure' seizures," said Noebels.

Why some children have a more complicated set of disorders beginning with major motor spasms in infancy followed by cognitive dysfunction and developmental disorders such as autism remained a mystery until the discovery by the BCM team that a mutation in only a single gene explains all four features of catastrophic epilepsy.

A gene known as Aristaless-related homeobox or ARX has a specific mutation called a triplet repeat, which means that a particular genetic (in this case, GCG) is repeated many times in the gene.

When the researchers duplicated this particular mutation in specially bred mice, the animals had motor spasm similar to those seen in human infants.

Recordings of their brain waves showed that they had several kinds of seizes, included absence epilepsy and general convulsion. They also had learning disabilities and were four times more likely to avoid contact with other mice than their normal counterparts.

This behaviour is similar to that seen in children with autism or similar disorders in the same spectrum.

"The new model is an essential tool to find a cure for the disorder," said Noebels.

The study appears in the current issue of the Journal of Neuroscience. (ANI)