AUSTRALIAN researchers have discovered a gene they believe is responsible for the most common form of epilepsy, opening the door to genetic screening.
The researchers also suspect a link between this gene and other neurological issues, such as autism and some psychiatric disorders.
The discovery, by researchers at the Universities of Melbourne and South Australia, has been described as a major breakthrough.
Until now, many experts believed this type of epilepsy came from a neurological trauma, such as a hit on the head.
"This is going to completely shift thinking," Professor Ingrid Scheffer, the study's senior author and a paediatric neurologist, said. "Instead of saying 'we don't know the cause', they can test for this gene."
About 25 genes for rarer types of epilepsy have already been found - more than half of them by Australian scientific groups.
But this gene causes focal epilepsy, which affects 60 per cent of people with epilepsy.
In this form of the disorder, the seizure comes from a specific part of the brain, such as the frontal cerebral cortex, although the gene causes seizures coming from different parts of the brain in different people. Seizures most commonly come from the temporal lobe or the frontal lobe.
"For the patient the discovery means a few things," Professor Scheffer said.
"Once this gene becomes available for testing, sufferers might get to the causation of their epilepsy, and everyone wants to know why they have a disease. It helps with genetic counselling - for example, for people who carry the gene and want to have children.
"If you have this gene, you have a 60 per cent to 70 per cent chance of having epilepsy.
"If you don't have seizures and you do have this gene, you can still pass on your risk to the child."
But the scientists also noted another phenomenon - brain disorders such as autism and intellectual disabilities were higher in the families carrying the gene that were studied during the research.
"In rare cases, it is linked to the gene," Prof Scheffer said.
"We are not 100 per cent sure it's the gene doing it, but we think it might be."
The researchers studied about 90 families. Between 2 and 4 per cent of Australians suffer from epilepsy.
Originally published as Gene test hope for common epilepsy