U. closes in on the genetics of autism

University of Utah researchers believe they know the general area where one gene that causes autism may lie. But they need the help of families with at least one member who has the behavioral disorder if they are to narrow the search further.

Their study, published in Human Heredity online, is part of the Utah Autism Research Project, which uses, among other tools, Utah's vast genealogical resources, including the Utah Population Database containing computerized genealogies of 170,000 Utah families with 1.6 million individuals. Some of the information dates back to pioneer days.

The researchers used DNA from thousands of genes to conclude that a region on chromosome 3 probably is home to a gene causing autism, said primary author Hilary Coon, research associate professor of psychiatry at the U.

The scientists reached that conclusion by tracing variations in the DNA of a multi-generational Utah family that has an unusually high occurrence of autism. They looked at 31 members of the family, which is of Northern European descent and all descended from one couple. Seven of those members have autism or a related disorder.

Along the way, they also ruled out one candidate gene they thought would prove to be linked to autism, Coon said.

Autism strikes young children and is marked by impaired ability to relate to others and to communicate. Repetitive behaviors are common.

The research tends to confirm recent Finnish studies of families that also target the same region of chromosome 3, Coon said. That's good news, because it suggests the researchers are on the right track, she added.

Autism is likely not the result of a single gene mutation; a number of genes may be implicated in versions of the disorder. It may also vary from family to family, which is why they want more research subjects, she said.

If it proves out, there may be other genes on other chromosomes that can cause autism, as well.

The technical part of the study involved use of a glass chip containing short segments of DNA with known gene sequence variations. The DNA strands of study subjects were broken up and bonded to the DNA on the chip, allowing a very detailed look at gene sequence variations between the two. The chance of the same variants in a region of a chromosome being passed through several generations of a family to multiple affected members is slight, researchers said. Those kinds of identical blocks mark the chromosome region as a good place to look for a link to the disease.