Researchers Identify Genetic Role In Autism

MINNEAPOLIS -- Researchers have come one step closer to determining the genetic basis for autism.

Scientists funded by the National Institutes of Health, in collaboration with their European colleagues, have identified regions of four chromosomes that appear to be linked with the disorder.

"These findings confirm the role of genetics in autism and are a major step in narrowing the search for the specific genes involved," said Dr. Duane Alexander, director of the National Institute of Child Health and Human Development and co-chair of NIH's Autism Coordinating Committee.

At least one in 500 people are affected by some form of autism, a disorder that causes problems with communication and social interaction, as well as repetitive actions and interests.

Earlier studies with families and twins have shown that there is likely to be a strong inherited component to autism. Because of the wide range of patients' symptoms, many researchers suspect the disorder is the result of an interaction between several different genes involved with brain signaling and development. Environmental factors are also likely to play a role.

In this study, researchers screened the DNA of more than 150 pairs of siblings with autism. They found extremely strong evidence that two regions on chromosomes 2 and 7 contain genes that are involved with autism. Likely locations for autism-related genes were also found on chromosomes 16 and 17, although the strength of the correlation was somewhat weaker.

The findings will appear in the September issue of the American Journal of Human Genetics.

Researchers were particularly excited by evidence of an autism link on chromosome 2, since this area had recently been identified by another, independent research group.

"We wouldn't be looking for genes on chromosome 2 if not for these findings. Now we can be fairly certain that genes on chromosomes 2 and 7 are linked with autism," said Dr. Ed Cook from the University of Chicago, a participating researcher on the project.

"Teams from all over the world worked together to produce this result," said Dr. Bristol-Power. "This kind of collaboration is how the problem of autism will eventually get solved.

"Even larger numbers, 400-500 pairs of relatives, are needed to get more definitive answers, and collaborative international efforts to complete a genome scan on such numbers are now under way."

This work was carried out by members of the International Molecular Genetic Study of Autism Consortium, a group of clinicians and scientists from the UK, United States, France, the Netherlands, Denmark, Italy and Greece.

Researchers currently know little about what is going wrong in the brains of autistic children, and they hope to gain answers by locating the specific genes involved and understanding their functions.

"We will continue to search for the individual genes which are linked with the development of autism," said Dr. Fred Volkmar of the Yale Child Study Center. "Knowledge of the genes will lead us to better, earlier diagnoses and interventions and, ultimately, better treatment options."