Autism's roots: mix of chance and genetics.

Byline: Dennis O'Brien

Mar. 16--Researchers probing the roots of autism say they've found fresh evidence that the disorder, like cancer, could be a tough one to conquer. That's because it's really a constellation of related diseases -- with a wide range of genetic underpinnings. In a study released today, scientists say that children who are the sole cases of autism in their families are five times more likely to have a particular genetic mutation than autistic youngsters in families in which the disorder has shown up repeatedly. That confirms what experts have suspected for years: that there might be dozens of genetic anomalies responsible for the symptoms now collectively diagnosed as autism spectrum disorders.

"I think it says something fundamental about autism, that you can kind of think of it as a collection of rare syndromes. Each might have a different genetic basis, but…