From: Penn State
Published June 23, 2017 03:53 PM

Genes, Ozone, and Autism: Increased risk for autism when genetic variation and air pollution meet

A new analysis shows that individuals with high levels of genetic variation and elevated exposure to ozone in the environment are at an even higher risk for developing autism than would be expected by adding the two risk factors together. The study is the first to look at the combined effects of genome-wide genetic change and environmental risk factors for autism, and the first to identify an interaction between genes and environment that leads to an emergent increase in risk that would not be found by studying these factors independently. A paper describing the research appears online in the journal Autism Research.

“Autism, like most human diseases, is complex,” said Scott B. Selleck, professor of biochemistry and molecular biology at Penn State and one of the leaders of the research team. “There are probably hundreds, if not thousands, of genes involved and up until now -- with very few exceptions -- these have been studied independently of the environmental contributors to autism, which are real. Our team of researchers represents a merger of people with genetic expertise and environmental epidemiologists, allowing us for the first time to answer questions about how genetic and environmental risk factors for autism interact.”

The team looked at copy-number variation -- deletions and duplications of repeated elements in the genome that lead to variation among individuals in the number of repeated elements -- as a general measure of genetic variation and five types of air pollution -- traffic-related air pollution, nitrogen oxides, two sizes of particulate matter, and ozone -- in a large set of individuals with autism and a well-matched set of typically developing controls. The study participants -- obtained through the Childhood Autism Risks from Genetics and Environment (CHARGE) Study, a population-based case-control study led by Irva Hertz-Picciotto, professor of epidemiology and chief of the Division of Environmental and Occupational Health at University of California Davis, and one of the leaders of the research team -- includes cases and controls matched for age, sex, and geographic location. Each of 158 cases and 147 controls were genetically scored for genetic deletions, duplications, and total changes in copy number. Environmental exposures for each participant were determined based on residential histories using data from the U.S. Environmental Protection Agency (EPA) Air Quality System.

Continue reading at Penn State

Image: Genes, Environment, and the Risk for Autism: Environment factors (ozone) can interact with genetic factors (copy number variation) to produce an even higher risk for autism than expected by adding the two risk factors, one that might not be found by studying the factors independently. (Credit: Penn State University)

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