Missing DNA the culprit in epilepsy?

An international team of scientists have identified a genetic risk factor for epilepsy which may lead to a better understanding of what causes the seizures and the development of new treatments for the condition.

Epileptic seizures are triggered by the abnormal, synchronised firing of neuron groups, resulting in a disruption to the central nervous system which causes spasms and convulsions.

The team led by Dr. Thomas Sander, from the University of Cologne in Germany, have discovered a missing segment of DNA which could be the culprit in unexplained seizures defined as "idiopathic", meaning that their origin is unknown.

The researchers focused on a region of chromosome 15, one of the packages of DNA found within the nucleus of every cell, which in the past been linked to mental retardation, schizophrenia, autism and epilepsy.

The discovery came about after the team genetically screened 647 people with idiopathic generalised epilepsy (IGE) and compared them with 1,202 healthy individuals and they found a deleted section of DNA on chromosome 15 in 1% of IGE sufferers who did not have mental retardation or a psychotic illness.

The deleted section contained at least seven missing genes including CHRNA7, which is responsible for regulating signalling at neuronal synapses, the junctions between nerves.

It is already known that mutations in other members of the same gene family cause a rare form of epilepsy, which suggests that the loss of CHRNA7 may account for the link between chromosome 15 and IGE.

The researchers say the deletion was "the most prevalent risk factor for common epilepsies identified to date."

The research is published in the journal Nature Genetics.