Risk of autism in siblings nearly double prior estimates | Newsroom | Washington University in St. Louis

Risk of autism in siblings nearly double prior estimates | Newsroom | Washington University in St. Louis

Siblings of children with autism are known to be at increased risk for autistic spectrum disorder (ASD), but now researchers from 12 sites in the United States and Canada report the risk is substantially higher than previously believed and much higher than the risk for children in the general population.

Past studies have estimated the risk for those siblings at 3 percent to 10 percent, but new results, published in the September issue of the journal Pediatrics, show that 19 percent of infant siblings develop ASD by age 3. In families where more than one child was affected, an infant sibling’s risk topped 32 percent.