A series of studies published in the journal Neuron find that genetic mutations may be the underlying cause of a major portion of autism spectrum disorders (ASD). Led by Dr. Matthew W. State, associate professor of psychiatry and genetics at Yale University, the study found that 25 percent of ASD cases are caused by inherited gene mutations passed on from parent to child. But what about ASD cases that arise in children with no family history of the disorder? Well, after analyzing the DNA of over 1,000 families with a child who has ASD (but with parents and siblings who do not), researchers found that the disorder was associated with rare DNA duplications and deletions that occurred spontaneously in 8 percent of children with ASD, compared to 2 percent of their unaffected siblings.
According to the CDC, about 1 in 110 U.S. children has ASD, a rate that has reportedly been increasing over the past few decades. Some attribute this rise to greater awareness and better diagnosing of the disorder, but Dr. Irva Hertz-Picciotto, an autism researcher and professor of public health at UC Davis, thinks that environmental exposures may be playing a role.
ACSH's Dr. Gilbert Ross wonders what exactly she means by “environmental exposures.” “She’s being intentionally vague,” he notes. “The recent studies seem to indicate that genetics plays a large role in the incidence of ASD, and while certain environmental factors may make the expression of these genetic factors more likely, to simply come out and state it as fact, like Dr. Hertz-Picciotto did, is not based on any evidence we have to date.”
ACSH's Dr. Josh Bloom adds, “Another recent study concluded that prenatal vitamins help protect against autism to some degree. Between the vitamin and genetics studies, it is clear that autism is a very complicated problem. Blaming the ‘epidemic’ — to whatever extent the incidence is actually rising — on the environment is oversimplified, self-serving and, probably, wrong.”