Rare genetic glitch that greatly increases autism risk identified

TRENTON, New Jersey (AP) — A rare genetic variation dramatically raises the risk of developing autism, a large study showed, opening new research targets for better understanding the disorder and for treating it.

Research into the causes of autism has focused on genetic causes because so many families have multiple children with the disorder.

Thus far, only about 10 percent of autism cases have a known genetic cause. Boston-area researchers estimate the gene glitch they have identified accounts for another one percent of cases.

They found a segment of a chromosome which has genes linked to brain development and various developmental disorders were either missing or duplicated far more often in autistic people. The defect was inherited in some cases, but more often the result of a random genetic accident.

The results from the Autism Consortium study, released online by the New England Journal of Medicine, confirm those of smaller studies by US and Canadian research groups in the past year.

The consortium verified its findings by checking two other DNA databases in the US and Iceland.

“They really did nail it,” said Dr. Andrew Zimmerman, director of the Kennedy Krieger Institute’s Center for Autism and Related Disorders in Baltimore, who was not involved in the research.

He predicted children newly diagnosed with autism or other developmental disorders now will be tested for this defect on chromosome 16 and that studies of many more DNA samples may reveal other autism-related gene variations.

Already, the findings are starting to be used to give some parents long-sought answers to burning questions: What caused autism in their child and how likely is it that any future children also would have autism, long known to run in families?

Autism, a complex, poorly understood disorder, is characterized by repetitive behaviors and poor social interaction and communication skills.

Research has mainly centered on genetic causes, and on whether it could be caused by the mercury-based preservative once used in childhood vaccines, which has been repeatedly discounted.