Researchers have found a gene linked to the most common form of epilepsy that could one day lead to a genetic test for the condition. They suggest the discovery will also give new insights into other neurological conditions such as autism.

Lead researcher, Ingrid Scheffer, professor and pediatric neurologist, of the Florey Neuroscience Institute in Melbourne, Victoria, Australia, and an international team of colleagues, write about their discovery of the focal epilepsy gene in the 31 March online issue of Nature Genetics.

Scheffer said in an interview broadcast on the ABC News AM radio show on Monday:

“This discovery is paradigm shifting.”

Epilepsy affects about 1 in 50 people. There are many different forms, but about 60% of epilepsies are known as focal epilepsy or partial epilepsy, where the seizures come from one part of the brain.

It was thought that this type of epilepsy was only caused by brain injury or tumors, but Scheffer says their discovery means:

“…if you have focal epilepsy and there is no cause known, then this gene should be tested to look for a mutation.”

She and her colleagues made their discovery after studying about 90 families where two members had epilepsy.

Their results showed that a gene called DEPDC5 causes focal epilepsy in about 12% per cent of families in which only two people have focal epilepsy.

In their study report they write:

“This high frequency establishes DEPDC5 mutations as a common cause of familial focal epilepsies.”

As well as opening new opportunities for diagnosing epilepsy, the researchers believe their discovery will also lead to better targeted treatments.

But Scheffer cautions there is a still a way to go. First we need to understand more about DEPDC5. All we know at present is that the protein it codes for is involved with signalling inside cells.

When we understand what goes wrong, then we can start to think about targeting it and “really improve outcomes,” she adds.

In the families they studied, the researchers noted there were some individuals with intellectual disabilities, and some with autism spectrum disorders and psychiatric features.

Scheffer says they think DEPDC5 may well play a role in these other disorders too, but they will need to study a lot more patients with the gene mutations and these disorders to establish a causal connection.

In another recent study led by Columbia University Medical Center in New York, researchers propose that epilepsy and migraine share a genetic link.

Written by Catharine Paddock PhD