By MARK ROTH
Pittsburgh Post-Gazette

In families that have children with autism, nearly half the risk of getting the brain disorder comes from inheriting an accumulation of common genetic variations from the parents, a new study shows.

The research, being published today in the journal Molecular Autism, showed that in families with only one child with autism, about 40 percent of the risk for the disorder is inherited. In families with two or more children with autism, about 60 percent of the risk is inherited.

The study involved analyzing genetic variations known as single nucleotide polymorphisms in thousands of families that had donated genetic material to the Simons Simplex Collection, where only one child has the disorder, or the Autism Genome Project, where two or more children in a family have it.

Read more from Pittsburgh Post-Gazette.