The really novel aspect to this gene is its involvement in epilepsy as well as in intellectual disability

Dr Jozef Gecz, Women's and Children's Hospital

Epilepsy and learning difficulties often occur together and frequently have genetic causes.

In the UK, around one in every 130 people has epilepsy, a neurological condition which describes the tendency to have recurrent seizures.

The researchers were puzzled that the same mutation in this gene can give rise to a range of conditions.

These include epilepsy, West syndrome (a type of epilepsy affecting children), dystonia (a muscle tone disorder causing muscle contraction) and learning difficulties.

But they suggest the way the master gene affects other genes could hold the answer.

Genetic mutation

Researchers obtained genetic material from nine families in Norway, Canada, Belgium, and Australia.

Dr Jozef Gecz, from the hospital's Department of Cytogenetics and Molecular Genetics, led the research.

He said: "This gene is found on the X-chromosome and is one of probably 100 genes on that chromosome, which when mutated, can cause intellectual disability.

"The really novel aspect to this gene is its involvement in epilepsy as well as in intellectual disability."

He said more work needed to be done to isolate other genes affected by the master gene and to establish why the same mutation could cause different conditions.

"It will be very interesting to know the identity of these genes that are under control of this master gene as they may potentially be involved in either epilepsy, intellectual disability, or both."

A spokesperson for the British Epilepsy Association told BBC News Online: "We view this recent research with considerable interest.

"Epilepsy that effects children, such as West Syndrome, can have a considerable impact on families, so anything that could potentially help these families or increase understanding about the condition is to be welcomed.

"We would certainly like to see�further research into genetics and epilepsy because there is still not enough understood about the link between the two."

The research is published on the website of the journal Nature Genetics.