Loss of a protein involved in amino acid breakdown leads to a new form of autism with epilepsy, according to a paper published in Science (338, 394–397).

Gaia Novarino et al. performed whole-exome sequencing in families in which at least two siblings had autism, intellectual disability and abnormalities in their electroencephalogram. This allowed them to find inactivating mutations in the gene encoding branched chain ketoacid dehydrogenase kinase (BCKDK), an enzyme that regulates the catabolism of branched-chain amino acids, in the affected individuals.

In Bckdk-knockout mice, the authors observed behavioral abnormalities such as tremors and seizures but could not ascertain the molecular mechanism behind these deficits. But, crucially, the neurological phenotypes of the mice improved when they were fed a diet rich in branched-chain amino acids, raising the possibility that this form of autism may respond to dietary supplementation.