Rare form of autism might be treatable with diet

Autism is a neurodevelopmental condition characterised by impaired social interactions. It is heritable, but each case probably involves a unique combination of genetic mutations, and there are no effective treatments.

A research team led by Gaia Novarino of the University of California, San Diego, has identified genetic mutations which cause a form of autism that could potentially be treated with dietary supplements.

The researchers, including Nagwa Meguid and colleagues from the National Research Centre in Cairo, Egypt, performed whole exome sequencing on two consanguineous families, one of Egyptian and the other of Turkish descent. All members with autism also suffered epileptic seizures and intellectual disability.

They identified two different mutations in the gene encoding an enzyme called BCKDK, which normally inactivates a protein complex that metabolizes branched chain amino acids (BCAAs). Those with two copies of the mutated gene have reduced levels of BCKDK and BCAAs in their bloodstream.

The researchers also examined genetically engineered mice lacking the BCKDK gene, and found that they too have reduced BCAA levels. They exhibited neurological abnormalities such as seizures, which were completely abolished within one week of feeding the mice a diet rich in BCAAs.

Now, the researchers have already started to test the effects of a BCAA-supplemented diet on people. "They are doing well and we have not noticed any side effects," says Novarino. "We can see an elevation of BCAA levels to within the normal range, but we are still working on supplementation dose and frequency.

"It is too early to predict an outcome, but I imagine that supplementation would work and possibly prevent symptoms if started early enough. It is probably a very rare disorder, but it could be very important to screen newborns for it."

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