A new study from the Icahn School of Medicine at Mount Sinai offers yet more findings about the genetics of autism spectrum disorders (ASD). Current research indicates that there may be as many as 1,000 genes involved in ASD, but the research team from Mount Sinai led by Dr. Joseph Buxbaum, professor of psychiatry, genetics and genomic sciences, and neuroscience, focused on gene deletion and duplication. They found that seven percent of the ASD population surveyed was missing copies of certain genes that should be present in pairs.

This study focused on what are called copy number variations; that is the deletion or duplication of particular genes. The researchers used exome sequencing (a process for selectively sequencing the genome) to analyze a set of 22,000 genes in 431 people with ASD and 538 people without ASD. Using the eXome Hidden Markov Model program, the researchers were able to create the first tool to identify single gene changes in the genome. The analysis revealed that the ASD individuals exhibited a greater likelihood of having multiple, small gene deletions than their non-ASD peers.

Further analysis of the types of genes deleted revealed that a significant amount of the genes deleted from the ASD group were related to autophagy, a process that is related to cell health. The authors explain that there is significant evidence that autophagy is a critical part of brain development because it “prunes back” excess synapses. The authors also suggest that the missing genes could be the cause of the “miswiring” of brain neurons

The study offers the first evidence that small deletions impacting only a few genes are apparently common in individuals with ASD.  This research may aid the development of genetic testing for ASD.

This research is published in the American Journal of Human Genetics.

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