New evidence of a genetic reason for autism

Posted Dec 9, 2016 by Tim Sandle
The causes of autism are varied. However one reason for some people with an autism spectrum disorder is likely to be genetic. New research has identified a new genetic cause.
A boy with autism makes a bead necklace on March 2  2012  in Isle d'Abeau  France
A boy with autism makes a bead necklace on March 2, 2012, in Isle d'Abeau, France
Jean-Philippe Ksiazek, AFP/File
Autism spectrum disorder is a neurodevelopmental disorder that affects social interaction, communication, interests and behavior. Autism spectrum disorders affect about one percent of the world's population. The causes are complex and varied and include connections to genes as well as individual microbiomes (microbial populations in the gut). In addition, environmental factors are probably influential and are associated with the condition.
The new genetic connection comes from the Institute of Science and Technology Austria. Here Professor Gaia Novarino has discovered a new autism-linked gene. Furthermore, the researcher has pinpointed the mechanism by which a mutation occurs with the gene which can cause autism.
Professor Novarino explains how the discovery of the gene was undertaken and the complexities involved in a research note: “The identification of novel genes, especially in heterogeneous diseases such as autism, is difficult. However, as result of a collaborative effort, we were able to identify mutations in a gene called SLC7A5.”
The role of SLC7A5 is to transport a specific type of amino acid called branched-chain amino acids (BCAA) into the brain. To test out the effect of the mutation, studies were carried out using mice. The rodents were genetically engineered to have SLC7A5 is removed at the barrier between the blood and the brain.
The effect of this was to lower the levels of BCAAs in the brain and the consequence of this was to interfere with protein synthesis in neurons. This led to the behavior of the mice changing with reduced social interaction, which corresponded to previous autism mouse models.
As a sign of a potential breakthrough, the researchers were able to treat some of the neurological abnormalities in the adult mice missing SLC7A5 at the blood-brain barrier. This was through artificially delivering BCAAs directly into the brain. This led to some positive alterations with the behavioral symptoms. Things are a long way off such a treatment being undertaken on people with autism, however.
The findings are published in the journal Cell, with the research paper titled “Impaired Amino Acid Transport at the Blood Brain Barrier Is a Cause of Autism Spectrum Disorder."