Researchers said genetic mutation responded to amino acid supplement, which may mean some rare forms are treatable.
A rare form of autism tied to seizures and mental retardation may be treatable with a simple diet change or supplement, said a study that suggests similar approaches might work for other forms of the disorder.
Researchers identified gene mutations in two families with the unusual autism and found the mutations caused lower levels of certain amino acids in their blood. In an experiment described Thursday in the journal Science, mice bred with the same gene mutations that were given a supplement of branched chain amino acids or BCAA had fewer seizures and improved autism symptoms.
BCAAs are essential nutrients that the body can't make. It is acquired through proteins in foods such as meat and dairy. Supplements containing these amino acids are promoted for helping reduce muscle breakdown during exercise and increase mental concentration. They've also been used to treat patients with amyotrophic lateral sclerosis, or Lou Gehrig's Disease.
The next step is to see if the supplement does the same for patients with the uncommon autism, researchers said. While the autism found in the two families is rare and may not affect other people, the discovery might help identify other forms of autism, said Gaia Novarino, an author of the study and scientist at the University of California, San Diego.
"This can be an example that there possibly are rare forms of autism that are treatable," Novarino said. "We don't know how many there are out there. So that's what we want to look at and find."
About 1 in 88 children in the United States are diagnosed with an autism-related condition. The disorder hurts brain development and is linked to poor social interaction and communication skills, repeated body movements and unusual attachments to objects. Twenty five percent of autistic children also have epilepsy, said the study by researchers from Yale University and the University of California, San Diego.
Because the disorder affects individuals in a wide spectrum of ways, researchers have begun comparing autism to cancer and investigating potential genetic and environmental causes. As with cancer, it is difficult to pinpoint how or why autism strikes some people.
The study focused on a gene, Branched Chain Ketoacid Dehydrogenase Kinase, that was found in a family of Turkish descent and one of Egyptian ancestry through sequencing their exomes, or the region of the genome that creates proteins. The particular genetic variant is related to another disorder called Maple Syrup Urine Disease, where the opposite occurs.