The cause of autism spectrum disorders (ASDs), the fastest growing developmental disability in the United States, is still a big mystery. While there’s clearly a genetic component, only 15 percent of people with autism have a known genetic cause. But researchers believe that a much larger percentage of autism can be chalked up to genetics. Now, Children’s Hospital Boston and Autism Consortium researchers have shown that a new genetic test, which samples the whole genome, may work three times better than standard tests.

Families expecting a child who have a family member with an ASD sometimes seek genetic testing to determine whether their baby is at risk.  In a child who’s already affected, genetic testing can explain why the child has autism and let the parents know how likely it is that other children in the family could inherit the genetic risk for autism. …