Shedding more light on what’s behind the developmental disorder, new research suggests that people with autism are more likely to be missing genes than those who are typically developing.

In a genome analysis of more than 800 people, researchers found that gene deletions were more common in those on the spectrum. That means that individuals with autism had a single copy of one or more genes when they should have had two.

“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,” said Joseph Buxbaum, a professor of psychiatry, genetics and genomic sciences and neuroscience at the Icahn School of Medicine at Mount Sinai who led the study published this week in the American Journal of Human Genetics.

Such gene deletions may cause brain neurons to be miswired and behave differently, the study found, increasing chances that a person will develop autism.

For the study, researchers looked at 431 individuals with autism and 379 people without the developmental disorder. They found 803 gene deletions in those on the spectrum and 583 in the control group. Those with autism were more likely to have multiple small deletions, the researchers said.

While gene deletions are common and help make each person different from the next, the study found that some of the extra deletions seen in individuals with autism may be contributing to the disorder.

A significant number of these extra deletions were related to a process called autophagy that helps keep cells healthy and is believed to be important for brain development, the researchers said.

Further research is needed to fully understand the link between gene deletions and autism, Buxbaum indicated, adding that he and his colleagues are continuing to analyze the genomes of thousands of individuals with autism.