U. researchers find new link to autism

A trio of researchers from the University of Utah's department of psychiatry are part of an international team of scientists who may have found a new genetic link to autism.

The team is using genome information from 1,000-plus families with multiple affected individuals — including more than 150 Utah families.

The new research has identified a region of the human genome that may include susceptibility to autism, a developmental disability that typically appears during the first three years of life and affects a person's ability to communicate and interact with others. The findings of the new study, which was published Thursday in Nature, highlight the importance of genetic variation in the development of the disorder, which now affects one in every 150 American children, and almost one in 94 boys.

Previous attempts to identify genes that increase susceptibility to autism have yielded limited success.

"Autism and other autism spectrum disorders are complex diseases," said Dr. William M. McMahon, chairman of the psychiatry department at the University of Utah School of Medicine and a contributor to the study.

"While previous research and familial studies have suggested that there are strong genetic components that predispose to autism, this study adds to accumulating evidence that multiple rare mutations, rather than a single mutation, contribute to autistic susceptibility."

The scientists' first effort studied 1,031 families, including 1,553 children with autism, from the Autism Genetic Resource Exchange and U.S. National Institutes of Mental Health repositories. The researchers found that variations in a region on Chromosome 5 near a gene called Semaphorin 5A (SEMA5A) were linked to the development of autism. SEMA5A is a gene that is believed to be involved in axonal guidance, the process by which nerve cells send out fibers to conduct electrical impulses.

"Earlier studies have shown that the expression of SEMA5A is lower in the peripheral blood of individuals with autism," said Hilary Coon, a co-author on the study and U. professor of psychiatry. "It is reasonable to think that disruptions in genes involved in how axons in the brain find their correct targets might contribute to autism susceptibility, and this study provides additional evidence implicating SEMA5A."

The researchers conducted different studies using separate data from the Autism Consortium and other sources around the world, including from Utah, to confirm their findings.

The study also highlights just how complex the genetics are that underline autism.

"We are grateful for the enormous effort given by thousands of autism families from around the world, and particularly for the continued involvement of our local families here in Utah," Coon said. "These international collaborations may provide the keys to unlocking the secrets of complex diseases such as autism."

Judith S. Miller, a U. associate professor of psychiatry, also was a co-author on the study, which was funded in part by Autism Speaks, a national advocacy organization.

e-mail: lynn@desnews.com