Epilepsy gene pair may be 'seizure-protective'

Two defective genes, which normally cause epilepsy when inherited individually, have been found to protect against seizures when inherited as a pair, according to a report published in the journal Nature Neuroscience. The researchers, based at Baylor Medical Centre in Texas, found that mice genetically engineered to carry the two faulty genes, both of which are involved in regulating the flow of charged molecules in and out of cells, had dramatically reduced seizures and did not suffer the sudden death normally associated with mice carrying defects in the individual genes.

Scientists already knew that defects in the two genes - Kcna1 and Cacna 1a - were responsible for epilepsy in some families when inherited individually. Large-scale studies of people with non-inherited seizure disorders, performed in collaboration with the Baylor Human Genome Sequencing Centre, had also identified the two genes. They expected that mice genetically engineered to have defects both genes would be more prone to seizures, but surprisingly they found the reverse was true.

'In the genetics of the brain, two wrongs can make a right,' said Jeffrey Noebels, professor of neurology, neuroscience and molecular and human genetics at Baylor College of Medicine, believing that the defective genes may actually prevent seizures by acting as a 'circuit breaker', stopping the electrical storm of brain signals in its tracks.

Professor Noebels hopes that the discovery will help scientists to better understand the genetic basis of neurological diseases, potentially leading to new ways of treating epilepsy. 'If you have a potassium channel defect, then a drug blocking certain calcium channels might also benefit you', he said.

In future scientists may be able to more accurately assess an individual's genetic risk of many common disorders such as epilepsy, by testing for defects in different combinations of genes to create a complete profile of the genes involved, thinks Professor Noebels. 'Fortunately, this amount of background information will soon become routinely obtainable thanks to rapid technological progress in the field of neurogenomics', he said.