A rare form of autism,
caused by a mutation that alters amino acid metabolism, could potentially be
treated with a nutritional supplement, according to an international team of
researchers. This finding may also lead to an effective test for the
condition using genetic biomarkers, helping earlier and more accurate
'This might represent
the first treatable form of autism', Professor Joseph Gleeson of the University
of California, San Diego, who led the study, said to the journal Nature. 'That
is both heartening to families with autism, and also I think revealing of the
underlying mechanisms of autism'.
Around a quarter of
people with autism spectrum disorder also present with epilepsy. Researchers analysed
the DNA of three families from the Middle East with children who have autism
spectrum disorder with epilepsy, specifically focusing on the regions of their DNA
that code for proteins. The children in question, who all had parents who were first
cousins, carried a mutation in a gene called BCKDK.
BCKDK prevents the
breakdown of specific amino acids, known as branched chain amino acids (BCAAs).
These are essential amino acids that have to be obtained from our diet. The
children with mutant BCKDK broke down these amino acids more quickly, leading
to a deficiency.
Mice engineered to
have the same genetic flaw, who had tremors and epileptic seizures, were given
food supplemented with BCAAs. Their symptoms subsequently improved, leading scientists to posit whether supplementing the diet of the people
with this particular mutation could also alleviate their symptoms.
'Studying the animals
was key to our discovery', said lead author Dr Gaia Novarino of the University
of California, San Diego. 'We found that the mice displayed a condition very
similar to our patients, and also had spontaneous epileptic seizures, just like
our patients. Once we found that we could treat the condition in mice, the
pressing question was whether we could effectively treat our patients'.
that an over-the-counter supplement did reverse the amino acid deficiency in
the autistic children, without causing any adverse effects. Future work will investigate
whether the supplement can indeed reduce the patients symptoms of epilepsy and autism.
The type of autism
addressed in the study is very rare and these particular results
may not therefore be applicable to other forms of autism. However, studying other
metabolic pathways may be of benefit, suggests Dr Daniel Geschwind, a
neurogeneticist at the University of California, Los Angeles.
'If five or ten percent [of autism cases] 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'.
The study was published
in the journal Science.