People with autism have extra gene deletions which may interfere with brain development

By Yikrazuul [Public domain], via Wikimedia Commons

Researchers have discovered that people with autism spectrum disorder (ASD) are more likely to have certain gene deletions than their peers without ASD. A gene deletion means that a person has only one copy of a gene when they should have two.  These gene deletions or missing genes may be the cause of irregular brain activity in people with ASD, according to researchers at Icahn School of Medicine at Mount Sinai.

Gene additions and deletions are a normal part of everyone's genetic make up. The gene deletions found in this study however, were not inherited. These gene deletions occurred during the formation of the egg or sperm, reports Joseph D. Buxbaum, PhD, the lead investigator of this study.

Although autism is highly heritable, the majority of autism cases cannot be attributed to known inherited causes, Dr. Buxbaum says.

"This is the first finding that small deletions impacting one or two genes appear to be common in autism, and that these deletions contribute to risk of development of the disorder," says Buxbaum. "This conclusion needs to be expanded in other independent samples of ASD so that we can truly understand how the risk manifests," he says.

Buxbaum and his colleagues examined the extra gene deletions found in people with ASD. They found that a large number of these gene deletions related to a process called autophagy. Autophagy is a normal process in which a cell destroys proteins and other substances. Autophagy can result in the death of a cell.  Researchers surmise that if autophagy is not occurring normally, it could effect brain development.

"There is a good reason to believe that autophagy is really important for brain development because the brain produces many more synapses than it needs, and the excess needs to be pruned back," Dr. Buxbaum says. "Too many, or too few, synapses have the same effect of not making communication work very well. It could mean that some synaptic connections come in too late and may not solidify properly."

Although these findings are very technical, the scientists involved believe they could have clinical significance.  Further study in this area is already underway.

The study, Identification of Small Exonic CNV from Whole-Exome Sequence Data and Application to Autism Spectrum Disorder, is published in the Journal of Human Genetics.

©Mary M Conneely T/A Advocacy in Action