Researchers believe they have found some of the edge pieces in the jigsaw puzzle that is autism spectrum disorder.
A new study has found that duplicated and deleted pieces of DNA in a number of different genes play a role in the development of autism, said study co-author Rita M. Cantor, a professor of genetics and psychiatry at the David Geffen School of Medicine at UCLA.
Advocacy groups are optimistic that the findings could lead to new treatments for the disorder. A number of autism researchers said the discovery could one day lead to earlier diagnosis and treatment. Although some cautioned that it's too early to say how big a step forward the gene findings are, they clearly show the important role of genetics in autism.
At the center of the issue may be stretches of DNA, called copy number variants, or CNVs, that appear to be more common in children with autism than in others.
"Children with autism have 20 percent more CNVs that disrupt genes," said Cantor.
The CNVs were found most often in genes that affect brain development than in other pathways that have nothing to do with the brain, she said.
And while these CNVs are common, they can vary greatly from person to person.
"They're not all seen in the same place, but they are ubiquitous," Cantor said.
The study compared nearly 996 people with autism to 1,287 control subjects and analyzed their genetic makeup to look for these CNVs.
"It's the largest study of this type thus far to get published," Cantor said.
While the researchers said these genetic variants don't cause autism, they do play a role in determining the risk for developing it.
Identifying genetic contributions to autism is an area of research that's expanding and shows a lot of promise.
"Discovery of the molecular pathophysiology will lead to biologically based treatments, which are especially needed for more severely affected individuals with autism spectrum disorder," said Dr. Nancy Minshew, another of the study's co-authors and professor of psychiatry and neurology at the University of Pittsburgh.
"The higher incidence of copy number variants in persons with [autism spectrum disorders] provides important insight into the genetic contribution to etiology," said Dr. Ernest Krug III, clinical professor of pediatrics at Oakland University William Beaumont School of Medicine. Krug was not involved in the study.
However, researchers and experts said a study like this one, while impressive, is only the beginning.
"We have a lot of work to do. We are going to have to identify more of these variants and get a catalog of what seem to be the variants that contribute to autism and then screen each child identified almost completely," said Cantor.
It's also vital to consider what other factors may be involved in the development of autism.
"We are still left with the contribution of environment and other epigenetic factors, since no one accepts genetic determinism when it comes to specific outcomes," said Krug.