Environment link to autism understated.

Posted by Heather Volk and Joe Braun

Two articles in Scientific American and the Los Angeles Times discuss three studies reporting that autism may be the result of mutations in hundreds of genes. The articles did a commendable job explaining three very complicated scientific studies and conveying the findings in a meaningful way. 

Autism is a developmental disorder commonly diagnosed before five years of age characterized by deficits in social interaction and communication, and often with repetitive behaviors. Rates of autism, and all autism spectrum disorders, appear to be rising and now may affect as many as 1 in 110 children.  

As pointed out by these two articles, scientists know very little about the causes of autism. In terms of genetics, there appear to be many genes associated with the disorder. Generally, each gene has small effects making it difficult to develop genetic tests for autism that can be used in diagnosis and early intervention.  

While briefly mentioned in both articles, the role of environment in the development of autism could have received more attention. Exposure to environmental factors like tobacco smoke, lead and stress during pregnancy can decrease IQ and influence the development of disorders like attention-deficit/hyperactivity disorder. Yet, few studies have examined whether these factors influence the risk of autism. Recent research has pointed to potential effects of air pollution, season of birth and prenatal vitamin use – all of which are areas that require additional research. 

Potentially even more important is the interaction between environmental and genetic factors. As pointed out in both articles, scientists are currently unaware of factors that contribute to the sort of genetic changes recently identified across the genome. Here, environmental factors may be important contributors to changes in gene function or underlying susceptibility. For example, one recent study suggests that children born to moms with certain genetic mutations that decrease their ability to metabolize folate (an essential vitamin) were at higher risk for autism if their mothers did not take prenatal vitamins.  

Ultimately, scientists and health professionals want to prevent autism and understand what causes the disorder. Examination of risks from both genetics and the environment may help us reach this goal.

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