The team hopes to conduct a properly controlled clinical trial looking at whether dietary supplements ease the children’s symptoms. To that end, Gleeson wants to identify further patients with mutations in the gene for BCKD-kinase. They are likely to be very scarce, he says, but metabolic screening and genome sequencing should identify some. “They’re hiding out there,” he adds.
Matthew Anderson, a physician-scientist at Beth Israel Deaconess Medical Center and Harvard Medical School in Boston, Massachusetts, says that the study will encourage other researchers to explore metabolic pathways as causes of autism. A number of uncommon metabolic disorders, such as phenylketonuria — in which the body can't break down the amino acid phenylalanine — can be linked to autism spectrum disorder if left untreated2. Many more such connections may be lurking in clinics.
“If 5 or 10% are caused by metabolic disorders and there’s a simple imbalance that one can correct with nutrition, that’s something that human genetics will identify over the next five to ten years,” says Daniel Geschwind, a neurogeneticist at the University of California, Los Angeles. “That’s exciting.”