“ You add an almost imperceptible amount of noise, and all sorts of wacky and unexpected things can happen. ” — DANIEL SOLLI, PAGE 12

In the News

Genetic analysis
reveals clues to
autism’s roots
Diverse disorder has common
molecular changes in brain
STORY ONE

By Laura Sanders

Though autism and related conditions vary widely from person to person, shared brain changes may be at the root of these afflictions.

Changes in the behavior of genes important for brain-cell development and function contribute to the poorly understood disorders, a study published online May 25 in Nature shows. Figuring out what goes wrong in the multifaceted disease will help scientists design better ways to treat it.

“For us to be able to develop specific therapies that treat the cause, you have to understand the genetics,” says pediatrician and autism researcher Hakon Hakonarson of the Children’s Hospital of Philadelphia.

In the study, a team led by Daniel Geschwind of UCLA analyzed post-mortem tissue from the brains of 19 people with autism spectrum disorder and 17 without. Patterns of gene activity differed in the two groups, as measured by levels of RNA molecules that shuttle information stored in DNA to the protein factories in cells. By sorting through these molecular patterns, the researchers turned up a number of abnormalities that the autistic brains shared.

For example, the researchers found that in unaffected samples hundreds of genes behaved differently depending on which of two very different areas were examined: one in the brain’s frontal lobe, the other in the temporal lobe on the side of the brain. But in the autistic brains, only a handful of genes acted differently in the two areas, despite the fact that the regions are involved in completely different tasks. The frontal region manages planning, impulse control and other high-level reasoning tasks; among other things, the temporal region helps govern language and how a person relates to others.

This lack of distinction in gene activity may have behavioral consequences and probably emerges very early in a child’s life, Geschwind says.

And though the affected brains dif-
fered from the unaffected brains, the
autistic ones were surprisingly similar
to one another, the team found. Among
the 19 autistic samples, patterns of gene
activity didn’t vary much from person to
person. Since the disease is thought to be
caused by a mishmash of many different
genetic and environmental factors, this
was an unexpected result.

Regional differences Gene activity is surprisingly uniform in the brains of people with autism. In a recent study eight genes differed greatly in activity between the frontal (dark blue) and temporal (light blue) regions of autistic people; in unaffected people, 510 genes showed differing levels.