In a finding that underscores the major role genetics plays in autism risk, researchers report they have identified 16 new genes linked to the developmental disorder.
The investigators conducted genetic analyses of 2,300 people from nearly 500 families with at least two children with autism. Of the children in the study, 960 had autism and 217 did not.
The researchers pinpointed 69 genes that were associated with an increased risk of autism, 16 of which had not previously been linked to the disorder.
The team also found several hundred genes they suspect may increase the risk of autism based on their proximity to genes previously identified with an increased risk, and also identified several new biological pathways not previously identified in autism research.
The findings improve understanding of how genetic variants or mutations are passed from parents to children with autism, said co-lead author Elizabeth Ruzzo, a postdoctoral scholar at the University of California, Los Angeles (UCLA).
"When we look at parents of autistic children and compare them to individuals without autism, we find that those parents carry significantly more, rare, and highly damaging gene variants," Ruzzo said in a UCLA news release.
"Interestingly, these variants are frequently passed from the parents to all of the affected children but none of the unaffected children, which tells us that they are significantly increasing the risk of autism," she added.
The study was published Aug. 8 in the journal Cell.
According to study senior author Daniel Geschwind, "Studying families with multiple children affected with autism increased our ability to detect inherited mutations in autism spectrum disorder."
Geschwind is a professor of human genetics, neurology and psychiatry at UCLA, and director of the UCLA Center for Autism Research and Treatment.
"We show a substantial difference between the types of mutations that occur in different types of families, such as those that have more than one affected child versus those having only one child with [autism]," Geschwind said.