The risk for autism is heightened when children who have a certain gene mutation connected with the disorder are exposed to high pollution, according to a new study by scientists at USC’s Keck School of Medicine.

Previous studies by USC researchers Heather Volk and Daniel Campbell found links between autism and air pollution exposure for pregnant women and infants. This one looked specifically at the MET gene - which researchers have already linked to autism -  and how it's affected when exposed to high amounts of air pollution, finding an augmented risk of Autism Spectrum Disorder in children.

“Although gene-environment interactions are widely believed to contribute to autism risk, this is the first demonstration of a specific interaction between a well-established genetic risk factor and an environmental factor that independently contribute to autism risk,” said Daniel B. Campbell, Ph.D., the study’s senior author. 

To date there is no cure for the disorder, which causes repetitive behaviors and social and communication problems. According to the Centers for Disease Control, one in 88 children in the United States has Autism Spectrum Disorder.

For this study, researchers studied 408 children between the ages of 2 and 5. More than half the children had a form of autism. The team took blood samples of the children to determine if the MET gene mutation was present. This information was then combined with an estimated pollution exposure reading based on traffic patterns from where the mother and child had lived.

Children who had the altered MET gene and lived in high pollution areas, had triple the risk for autism than children who had neither of the risk factors.

The research paper, “Autism spectrum disorder: Interaction of air pollution with the MET receptor tyrosine kinase gene,” will be published in the journal Epidemiology in January.