Latest Genetic Research May Help Decode Autism

(June 9) -- In a breakthrough that could help scientists develop accurate diagnostics and effective treatment for autism, researchers have pinpointed dozens of genes implicated in the illness.

But the new findings, published in this week's issue of Nature, also illustrate just how complicated this developmental disorder -- which affects a child's ability to communicate and relate to others -- really is.

Researchers compared the DNA of 996 children with autism and 1,280 children without it. They found dozens of genes whose copy number variants -- stretches of DNA that disrupt normal genetic function -- appeared to be more common among autistic kids.

Even then, only 1 percent of the genetic defects were shared among the study participants.

"Most people in the field believe autistic individuals share common genetic variations in perhaps just a few genes," Dr. Stephen Scherer, one of the study's authors, told reporters during a conference call. "The genetic variations we discovered are actually rare in frequency, meaning most individuals with autism are probably genetically quite unique, each having their own genetic form of autism."

Interestingly, not all the genetic defects were inherited from the child's parents. Rather, they seem to have arisen during fetal development or infancy.

The team anticipates eventually finding up to 300 implicated genes. None of the genetic defects is an outright culprit for autism, but the defects do leave children more vulnerable to developing the illness.

Once the myriad genetic anomalies are parsed out and identified, they could account for around 20 percent of autism cases, the researchers concluded.

And this study is only the start of an ongoing effort, called the Autism Genome Project, that includes 120 scientists in 11 countries. Next up, researchers hope to evaluate an additional 10,000 autism patients, to better understand the diverse genetic changes involved.

Within two years, they hope to have a full catalog of autism's genetic roots.

Gene-based treatments are likely years off, but the effort could help doctors make earlier diagnoses. That, in turn, would give specialists a chance to intervene while children are still in their early years.

"Currently autism diagnosis is entirely behavioral and lengthy, and parents are subjected to a long process where their child is being assessed," said Louise Gallagher, one of the study's authors, at Trinity College in Dublin. "Some children aren't getting a diagnosis until as late as 5 years old."

As for the other 80 percent of autism cases? Their cause -- along with the increasing prevalence of the illness, which now afflicts one in 150 children -- remains a mystery.

"The higher incidence of copy number variants in persons with [autism] provides important insight into the genetic contribution" to the illness' cause, Dr. Ernest Krug III, a professor of pediatrics at Oakland University, told ABC News. "[But] 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."