Rare genetic changes that predispose some people to autism have been discovered by an international team of scientists. This disorder that affects about one percent of children causes behavioral difficulties and it also impairs their ability to communicate.

A number of genetic mutations, called copy-number variants, in the genomes of children diagnosed with autism have been identified by the study.

According to the investigators in some cases the genetic abnormalities are inherited but in other autistic children these are unique.

Genomes of about 1000 autistic children were compared to about 1400 children who did not have autism. Researchers tried to search for the rare variants. It was found that in children who have neurological disorders these mutations occur 20 per cent more often.

Andy Shih, with the organization Autism Speaks, said, "With these findings you are starting to find some of the edge pieces. So, that would provide you with some sort of a framework for looking at how these genes work in autism and leading to the clinical features.”

Stanley Nelson, a professor of human genetics at the University of California in Los Angeles and co-author of the study, said, “While the mutations make individuals more susceptible to autism, the genetic abnormalities do not automatically mean someone will have the disorder.”