The scientists studied genetic information from 167 families of autistic children -- and found that a variant of one gene was twice as likely to be found in autistic children as in their unaffected brothers and sisters. It is not the first time a gene has been implicated in autism, but the scientists believe they have made one of the more compelling cases pointing toward an autism gene -- this one called Engrailed 2.
The study will be published in the May issue of the journal Molecular Psychiatry.
"This is among the most statistically significant evidence for any gene involved in autism," said James Millonig, co-investigator of the study and a researcher at the UMDNJ-Robert Wood Johnson Medical School in New Brunswick. The study also indicates that genetic alterations in the brain's cerebellum could be an important factor in autism.
The study also shows the power of parent advocacy in the field of autism, where there has been an explosion of research. The New Jersey study used genetic material collected by Cure Autism Now, a California advocacy group that has collected blood samples and other information from about 1,000 families with autistic children. Most of the families have more than one child with the disorder. Right now, 147 scientists are mining the data for clues into the mystery of autism.
Clara Lajonchere, a scientist in charge of the genetic data bank, issued an alert to members last week saying the New Jersey study provides one of the "most promising candidate genes in autism susceptibility."
"This work adds to the growing body of evidence that genes involved in brain development are important in autism susceptibility," she wrote. In an interview, Lajonchere said, "We have families with four or five children diagnosed with autism. You bet there is a genetic component."
Andy Shih, director of research for the National Alliance for Autism Research, in Princeton, called the evidence in Millonig's study "very strong. I think it's a promising lead." But he cautioned that other genes thought to be involved in autism have "not led to the answers we all hope for."
Autism fundamentally alters a child's ability to communicate, and those most severely affected can be lost in a world all their own. It is a complex disorder, and most scientists believe a combination of many genes, perhaps 10 or 20, are involved, along with environmental factors. One aim of genetic research is to discover what outside factors act on genetic susceptibilities.
"If we found somebody with a genetic vulnerability who did not get autism, it could be a powerful way to learn what we can avoid to prevent this illness," said Linda Brzustowicz, also a co-author of the study and a researcher at Rutgers University and the UMDNJ-New Jersey Medical School in Newark.
Millonig, who came to autism research with a background in mouse genetics, said he knew that nearly all autopsy studies of people with autism found a malformed cerebellum. The cerebellum is involved in language and attention, the very skills usually lacking in children with autism. Millonig knew certain genes were linked to a malformed cerebellum in mice. He used that knowledge as a road map to find human genes implicated in the same condition. Extensive testing eventually pointed to Engrailed 2.
Millonig said the tests must now be replicated.
"We need to do a lot more to provide further evidence. We need to test more families. We are in the process of doing that," he said. Millonig also wants to use imaging studies eventually to determine if the cerebellum functions differently in people who have inherited the Engrailed 2 gene.
About a decade ago, the National Institutes of Health funded $3 million of autism research and a spokesman for the National Alliance for Autism Research said about a dozen researchers focused on the disorder.
"Today, hundreds of excellent researchers are looking into autism. The next fiscal year the NIH will fund $90 million in research," said Joe Guzzardo, a spokesman for the Princeton group.
Advocacy groups like the one in Princeton have funded pilot projects, rarely for more than $100,000 each. But those pilot studies have attracted far more in federal funding for larger, more extensive follow-up research. The group also is now funding studies looking into environmental factors such as prenatal medication and childhood vaccines. Other studies are looking into pollutants, lead and pesticides.
Many scientists believe the disorder is on the rise. Lajonchere, of Cure Autism Now, said 1 in 166 children have autism or an autism-like disorder. "That's a prophetic and alarming statistic," she said.
Carol Ann Campbell covers medicine. She can be reached at firstname.lastname@example.org or (973) 392-4148