Roughly one-quarter of patients with autism also suffer from epilepsy, a brain disorder characterised by repeated seizures or convulsions over time.
The causes of the epilepsy are multiple and largely unknown. Using a technique called exome sequencing, the UC San Diego and Yale scientists found that a gene mutation present in some patients with autism speeds up metabolism of certain amino acids.
These patients also suffer from epileptic seizures. The discovery may help physicians diagnose this particular form of autism earlier and treat sooner.
The researchers focused on a specific type of amino acid known as branched chain amino acids or BCAAs. BCAAs are not produced naturally in the human body and must be acquired through diet.
During periods of starvation, humans have evolved a means to turn off the metabolism of these amino acids. It is this ability to shut down that metabolic activity that researchers have found to be defective in some autism patients.
"It was very surprising to find mutations in a potentially treatable metabolic pathway specific for autism," said senior author Joseph G Gleeson, professor in the UCSD Department of Neurosciences.
"What was most exciting was that the potential treatment is obvious and simple: Just give affected patients the naturally occurring amino acids their bodies lack," he said in a statement.
Using a nutritional supplement purchased at a health food store at a specific dose, the scientists reported that they could correct BCAA levels in mice with no ill effect.
The next step, said Gleeson, is to determine if the supplement helps reduce the symptoms of epilepsy and/or autism in humans.
The findings are published in the latest online issue of Science.
