DNA defect linked to 1 percent of autism cases

By Gene Emery

BOSTON (Reuters) - Researchers have identified a genetic defect responsible for 1 percent of the various forms of autism, and other experts said the DNA region involved could cause many more autism cases.

Identifying the genetic defect also offers another way to screen early for the disease, and perhaps to help children with treatments that can reduce some effects of the developmental disorder, researchers said.

A test for such genetic defects already is helping to inform parents with a child who has just been diagnosed with autism whether siblings might be at risk and whether future children might develop some form of autism, said Dr. Mark Daly of Massachusetts General Hospital, who led the study released on Wednesday.

Autism includes a range of disorders, from the mild Asperger's syndrome to profound mental retardation and lack of ability to socialize. It affects as many as 1 in 150 children in the United States -- up to 1.5 million children and adults.

Because "early intervention such as behavioral and educational therapy can have a positive impact on children who develop autism and other forms of developmental delay, any tool that can help give an earlier diagnosis at ages well before the formal diagnostic criteria kick in can be very useful," Daly said in a telephone interview.

The genetic defect identified in the study "may be the tip of an iceberg" as a cause of autism, Dr. Evan Eichler of the University of Washington, Seattle, and Dr. Andrew Zimmerman of John Hopkins University in Baltimore wrote in a commentary in the New England Journal of Medicine, where the study appears.

JUMBLING OF GENETIC CODE