Some autism cases linked to genetic mutation

The study findings could lead to more genetic testing to confirm diagnosis, improve access to educational services and give solace to parents.

By Victoria Stagg Elliott, AMNews staff. Jan. 28, 2008.

Up to 1% of autism cases may be blamed on too much or too little of a particular strand of an estimated 25 genes on chromosome 16, according to a pair of recent papers. Understanding how this creates the developmental disorder eventually may lead to improved treatment of autistic children, including those who don't carry these mutations.

"Each little piece of the puzzle gets us closer to the fundamental biological mechanisms, and if we understand the specific biological mechanism, we can consider how we might go about developing intelligent therapeutics for this disorder," said Mark J. Daly, PhD, assistant professor at Massachusetts General Hospital and Harvard Medical School.

One paper, published online Jan. 9 in the New England Journal of Medicine and co-authored by Dr. Daly, found that children with one or three copies of the 16p11.2 genetic segment, rather than the normal two, were at significant risk for autism. The other paper, published online Dec. 21, 2007, in Human Molecular Genetics, implicated having only one copy in this disorder.

These are two of the latest studies shedding some light on autism's genetic underpinnings. About 10% of cases can be explained by various genetic syndromes, such as fragile X or Prader-Willi syndromes, but the rest remain a mystery. Experts predict that no single cause will be found to account for a great number of the cases.

"Based on our experience with other human complex disorders, it's relatively infrequent that specific genes are much more than a percent or two of the whole story," Dr. Daly said.