Study Suggests Autism Causes Are Genetic

Feb. 18, 2007 — -- Scientists always knew it was devilishly complex.

Autism, is found in one of about every 150 people around the world, according to a recent Centers for Disease Control study. That figure has been disputed, but clearly autisim has many degrees and types, and piles of evidence hinting that genes -- not one but many genes -- are to blame.

But how to find them? It's like trying to find a few dozen innocent looking criminals in a crowd of millions.

Now, scientists have probable cause implicating dozens of prime suspects all corralled in one place -- the collection of 23 X-shaped chromosomes that hold our DNA and are found in every cell in the body.

The Autism Genome Project (AGP), by far the largest autism study ever, has tamed the immense complexity by using new computer technology that can read billions of DNA signals in a few minutes.

AGP Researchers at 50 study centers in 19 countries brought the new technology to bear on the genomes of 1,168 families that each had at least two autistic children.

"We had a few isolated suspect genes before," principal AGP investigator Steven Scherer of the University of Toronto told ABC News. "But now, for the first time, we can finally see the forest for the trees."

The massive new study pinpoints the probable culprits -- not just one but many genes and abnormalities -- on every one of the 23 chromosomes.

The findings also strongly suggest that different combinations of genes may cause the different degrees and kinds of autism found in different people -- ranging from mild to severe.

"Autism has such a wide spectrum. Every child presents differently," Theresa Wadell of Arlington, Va., told ABC.

She and her husband, Chris, have had three boys. The first two -- now aged 7 and 5 -- have mild autism.

"We always have to watch them," she says. "Each child is in their own world. Paul, he's all over the room. Will, who is older, is the quieter one."

"The message here," says another principle investigator in the study, Joseph Buxbaum, "is that there is great hope now."