Mutations boost autism risk, study says

Scientists have discovered a pair of genetic mutations that markedly boost a child’s risk of autism, according to research out today.

The mutations – missing or duplicated snippets of DNA on chromosome 16 – may raise the risk of autism at least 100 times, the study says.

Although the genetic errors are implicated in just 1 percent of autism cases, that amounts to a lot of children.

“There are probably a million kids in this country with autism. About 10,000 of them have this mutation,” said researcher David Miller of Children’s Hospital Boston, where a diagnostic test is available.

Scientists say the genetic errors occur before fertilization.

Doctors say the research marks a major turning point. Now, scientists are moving beyond simply describing autism and are probing its biological roots.

The finding bolsters the belief that autism-related disorders are genetic or developmental, not caused later in life by vaccinations.

Earlier studies indicate 90 percent of autism cases have genetic roots, but the source of the disorder had only been identified in 10 percent of patients.

In the new study, researchers for the first time scanned the entire genetic code of 1,441 children with autism or a related disorder and a similar number of parents whose DNA is stored at the Autism Genetic Resource Exchange. They also scanned the DNA of almost 1,000 patients from Children’s Hospital Boston and another 18,000 controls from Iceland whose DNA was analyzed by the firm DeCode.

Researchers found 13 children who were missing snippets of DNA and 11 who had duplications. In all cases, the children had autism or related problems, the researchers report in today’s New England Journal of Medicine.

“This might be the tip of the iceberg” of dozens of genetic errors, said Andrew Zimmerman of the Kennedy Krieger Institute Center for Autism.

“If we can identify children at risk for autism very early, we have the chance to intervene early while the brain is still developing,” said Annette Estes, of the University of Washington’s Autism Center Research Program.

Jean Yates, of Pound Ridge, N.Y., the mother of two boys with autism, 13 and 17, was elated to hear her family’s involvement in the exchange consortium made a difference.

“I wanted very badly to help,” she said. “We gave so much of our blood.”