Siblings of children with autism have a higher risk of being diagnosed with the disorder than once thought, according to a new study. The research, funded by Autism Speaks, analyzed more than 600 3-year-olds with an older autistic sibling and found that almost one in five of them eventually developed autism spectrum disorder, which includes Asperger syndrome among others. The findings are cause for pediatricians to keep a close eye on those siblings and use early intervention tools such as therapy to keep symptoms at bay. One in every 110 U.S. children has the disorder, and that number is unlikely to decrease anytime soon. The research is likely to call for more work to figure out what kinds of interventions are most helpful to children who begin to show signs of autism.