Epileptic encephalopathies are severe childhood seizure disorders that can lead to slow development and intellectual problems.
The genes of more than 500 children with the condition were analysed to find the cause.
In a study published today in Nature Genetics, researchers say they have found two new genes linked to severe epilepsy
The clinical leader of the study, paediatric neurologist Professor Ingrid Scheffer from the University of Melbourne, says it is hoped the discovery will help both children and their families better manage the disorder.
“Getting a diagnosis helps the family to move forward. It also saves the child from having unnecessary investigations,” she said.
“When you find the cause you can work out which treatments work best, and therefore if you can control seizures you might help that child’s development.”
Professor Scheffer says the breakthrough could even help diagnose the condition during pregnancy.
“Once you have a gene you can give very specific risks and you could test the next foetus to see if the baby is at risk of having the disorder.”
Researchers will use the discovery to develop targeted genetic therapies for affected children.