A rare form of autism that is accompanied by epilepsy and intellectual disability could be treatable with dietary supplements.

Joseph Gleeson and Gaia Novarino at the University of California, San Diego, and their team identified three affected families that carry mutated versions of a gene called BCKDK. The gene encodes an enzyme that slows the breakdown of branched-chain amino acids such as leucine and valine. Mice that lack both copies of the gene had low serum and brain levels of these amino acids, and showed neurological abnormalities and stunted growth. Enriching the animals' diets in branched-chain amino acids reversed these deficits.

Similar dietary enrichment normalized serum levels of branched-chain amino acids in people affected by the BCKDK mutation.

Science http://dx.doi.org/10.1126/science.1224631 (2012)