Over fifteen years since pinning infant epilepsy to a chromosome but failing to identify the gene responsible, Adelaide researchers have finally solved the mystery of the condition in infants.

Infant epilepsy is caused by a single mutation in one gene, the scientists confirmed.

The mutation causing infant epilepsy adds one more code to a 12-code sequence on chromosome 16, which affects a gene known as PRRT2.

The UniSA researchers made the discovery in conjunction with a team at the University of Melbourne. The work was published on Friday in the American Journal of Human Genetics, the Herald Sun reported.

The recent finding is expected to improve screening, diagnosis and prediction of the risk of seizures for infant sufferers of benign familial infantile epilepsy.

University of South Australia research fellow Dr. Susan Heron said over the weekend that benign familial infantile epilepsy, which is a relatively rare condition, occurred in about 60 Australian families.

She explained the gene they found responsible for infant epilepsy has never been linked to the condition in the past.

"It was difficult to find because it wasn't a gene that you would think about linking to epilepsy," she said.

Of 23 families previously diagnosed with benign familial infantile epilepsy, DNA analysis found the mutation present in 19 families.

Dr, Heron said children with the condition typically suffered seizures from the age of six months to two years.

While the seizures are bound to stop later in life, children with benign familial infantile epilepsy could suffer from a movement disorder when they get older.

"The children grow out of epilepsy but they can develop a movement disorder," Dr. Heron said.

With the research developments, families can now have their children screened for the disorder.

"If we can confirm what they have, we can better target treatment," she said.

The International League Against Epilepsy (ILAE) and the International Bureau for Epilepsy (IBE) define an epileptic seizure as a transient occurrence of signs and/or symptoms due to abnormal excessive or synchronous neuronal activity in the brain.

An estimated 50 million people worldwide have epilepsy, and nearly 90% of epilepsy occurs in developing countries, according to a WHO report in 2009.