July 6, 2011 1 Comment
Based on what I’ve learned, it’s always seemed most likely to me that autism almost had to be a result of both genes and environment. E.g., certain genes leave one vulnerable to certain environmental insults that lead to autism. Unfortunately, we don’t really know what those environmental insults are. Some new twin-based research suggests the environmental portion of this is much larger than previously thought:
Environmental factors play a more important role in causing autism than previously assumed and, surprisingly, an even larger role than genetics, according to a new study out of UCSF and Stanford that could force a dramatic swing in the focus of research into the developmental disorder.
The study, published in Monday’s issue of the Archives of General Psychiatry, looked at 192 pairs of twins in California and, using a mathematical model, found that genetics account for about 38 percent of the risk of autism, and environmental factors account for about 62 percent.
Previous twin studies had suggested that autism was highly inheritable, with genetics accounting for roughly 90 percent of all cases worldwide.
That’s quite an over-turning of the conventional wisdom. I’ve always felt lucky that Alex’s autism is one of the few cases (Tuberous Sclerosis Complex) where we know it’s 100% genetic. Not that it’s lucky he has autism, of course, but that we don’t face the uncertainty of so many parents. In some ways, this finding means only more anxiety for parents: 1) wondering what they did wrong in exposing their child to that lead to autism; or 2) becoming insanely hyper-vigilant to prevent those environmental insults of which nobody knows what they actually are.