January 25, 2006

Study Confirms Location of Potential Autism Gene

By Amy Norton

NEW YORK -- In another step toward unraveling the origins of autism, a new study confirms that a region of chromosome number 3 seems to be involved in the development of the disorder.

There was no evidence, however, that mutations in one suspect gene increase the risk of autism.

Analyzing DNA from 31 members of a family of Northern European ancestry in which 7 individuals had autism or an autism-related disorder, researchers found that a portion of chromosome 3 appeared to be linked with the disorder.

The investigators, from the University of Utah in Salt Lake City, say their findings are remarkably similar to previous ones by scientists in Finland -- confirming that a gene in this chromosomal region likely contributes to autism.

Autism is a developmental brain disorder that impairs, to varying degrees, a person's use of language and ability to communicate, interact socially and form relationships. Experts believe that genes play a central role in autism development and that variations in multiple genes are probably involved.

Scientists have found a number of chromosome regions that most likely linked to autism. The goal is to weed out the genes residing in these areas that confer susceptibility to the brain disorder.

Identifying the culprit genes will shed light on how autism develops, explained Dr. Hilary Coon, the lead author of the new study.

Understanding "even one mechanism" underlying the disorder, she told Reuters Health, could aid in creating new treatments.

Experts also hope that with the major autism genes in hand, they will eventually be able to screen young children for autism risk and begin behavioral therapy as early as possible. Autism is typically evident by age 3.

FXR1 has been considered a good "candidate" gene associated with autism risk, Coon noted. The gene is similar to an X-chromosome gene involved in fragile X syndrome, a genetic disorder that causes learning disabilities and other mental impairments.

However, when the researchers looked at FXR1, they found no evidence that mutations in the gene were related to autism, according to the report published online by the journal Human Heredity.

Her team's findings, Coon said, do not rule out a role for FXR1 in autism. It's possible that very subtle alterations in the gene that the study did not detect contribute to the disorder. The gene may also simply not be relevant in this particular family.

Coon and her colleagues are now focusing their research on other genes in the same chromosome region.

SOURCE: Human Heredity, online January 2, 2006.