While the microdeletion occurred in only 4 out of 712 subjects with autism, it is the second most common recurrent genomic disorder associated with autism, the university said in a release.

The findings are published in the journal Human Molecular Genetics.

The deletion of a small portion of chromosome 16, known as 16p11.2, results in the loss of about 25 known genes. "Twelve of those genes appear to be part of a single genetic network that includes genes involved in cell-to-cell signaling and interaction," said first author Ravinesh A. Kumar. "At least three of the deleted genes are primarily expressed in the brain and are thought to influence behavior."

The authors said the lost or damaged genes may also be involved in other cognitive, language and social impairments.

"Although this only explains about one-half of one percent of autism," said co-author William Dobyns, professor of human genetics and pediatrics at the University of Chicago, "it provides the best clues yet for finding the specific genetic changes that lead to the disease.