Autism's Possible Genetic Cause Comes to Light in New Study

DNA insertions and deletions may contribute to autism, researchers say.

June 9, 2010, 12:29 PM

June 9, 2010 -- 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.

Research Findings Very Encouraging

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.

Finding Holds Promise for One Parent

For one parent of a child with autism, this research is yet another tool in the arsenal to help her to learn more about this disorder.

"It gives us a variant we can work with and can test for," said Megan Brown, the mother of an 8-year-old son with autism. "If you know there's something wrong, you can say, 'Well, now I have the power, and I can do something about it,'" she said.

Her son is a high-functioning and does well in school, but trying to manage his condition every day is challenging.

"He has trouble carrying on a conversation," she said. "He can't follow along with me when we're talking."

She also has to bring him to a special school that's 45 minutes away from their home, and afterward, she brings him to special sports programs and other activities to help stimulate him.

Keeping him focused is another challenge.

"He requires a lot of redirection. He can get obsessed with certain toys or items, and I have to interrupt his play," she said.

And while this current study doesn't have any impact on her now, she hopes it can eventually lead to new treatments for children with autism.

Could Autism Findings Improve Treatment?

The researchers and medical experts hope for the same thing.

"Hopefully, we can treat many gene disruptions the same way and will be able to develop a general class of treatments down the road," said Cantor, one of the co-authors.

"It can improve treatment if research can demonstrate that certain genetic patterns respond preferentially to certain treatment approaches," said Krug.

But at least one other doctor believes treatments should be aimed at early intervention.

"What is most needed are strategies to identify kids early whose development is not on target and intervene," said Dr. Shlomo Shinnar, a professor of neurology, pediatrics and epidemiology and population health at Montefiore Medical Center, Albert Einstein College of Medicine. He is not affiliated with the current study.

For parents like Megan Brown, it's definitely another step in the right direction.

"It's just encouraging that they just keep going and that organizations are never going to give up," she said. "That, to me, is worth supporting."

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