Chromosome Abnormalities Raise Risk for Autism

By Amanda Gardner
HealthDay Reporter
Wednesday, January 9, 2008; 6:00 PM

Copyright © 2008 ScoutNews, LLC. All rights reserved.

WEDNESDAY, Jan. 9 (HealthDay News) -- Abnormalities on chromosome 16 appear to raise children's risk for developing autism, a new study suggests.

The discovery, made by a consortium of autism researchers, pinpoints one of the causes of a disorder that is turning out to be as complex in its origins as it is in its symptoms. Not only is autism complicated, its incidence has grown rapidly in recent years, with an estimated one in every 150 children in the United States now struck by the neurological disorder.

"This has given us another piece of the puzzle of the genetics of autism," said study leader Mark Daly, a member of the Autism Consortium with the Center for Human Genetic Research at Massachusetts General Hospital Center in Boston. "Autism is very complex, and we have only a few pieces in hand. We're trying to gain an understanding of the biological mechanisms underlying it. This is an opportunity to understand that."

According to the study, published Jan. 9 in the online edition of the New England Journal of Medicine, a section of chromosome 16 is deleted or duplicated in about 1 percent of people with autism spectrum disorders (ASDs). About 15 percent of autism cases have known genetic causes.

"We can only explain a fraction of all the kids with autism, and we know most have some genetic contribution," added study co-author Dr. David Miller, assistant director of the Genetics Diagnostic Laboratory at Children's Hospital Boston. "If we were making a top 10 list of the most important genetic factors contributing to autism that we know about, this would certainly be on that list."

However, some experts questioned the far-reaching value of the findings.

"These types of studies are association studies. They have to go many further steps to make a causal link," said Rajesh Miranda, an associate professor of neuroscience and experimental therapeutics at Texas A&M Health Science Center College of Medicine, in College Station. "This is also a very small proportion of autism patients. What it probably indicates is that autism is quite heterogeneous, and what we think of as one disease may be hundreds. The upside is this identifies a new way of looking at things."