Harvard Researchers - Autistic Genes stuck in off position.

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Harvard researchers find autistic genes stuck in " off " position

By LAURAN NEERGAARD

The Associated Press July 11, 2008

WASHINGTON

Harvard researchers have discovered half a dozen new genes involved in

autism that suggest the disorder strikes in a brain that can't

properly form new connections.

The findings also may help explain why intense education programs help

some autistic children, because certain genes that respond to

experience weren't missing, they were just stuck in the " off " position.

" The circuits are there but you have to give it an extra push, " said

Dr. Goldstein of the Kennedy Krieger Institute in Baltimore,

which wasn't involved in the gene hunt but is well-known for its

autism behavioral therapy.

The genetics suggest that " what we're doing makes sense when we work

with these little kids — and work and work and work — and suddenly get

through, " he said.

But the study's bigger message is that autism is too strikingly

individual to envision an easy gene test for it. Instead, patients are

turning out to have a wide variety, almost a custom set, of gene defects.

" Almost every kid with autism has their own particular cause of it, "

said Dr. Walsh, chief of genetics at Children's Hospital

Boston, who led the research reported in today's edition of the

journal Science.

Autism spectrum disorders include a range of poorly understood brain

conditions, from the mild Asperger's syndrome to more severe autism

characterized by poor social interaction, impaired communication and

repetitious behaviors. It's clear that genes play a big role in

autism, from studies of twins and families with multiple affected

children. But so far, the genetic cause is known for only about 15

percent of autism cases, Walsh said.

So Walsh's team took a new tack. They turned to a part of the world

with large families and a tendency for cousins to marry,

characteristics that increase the odds of finding rare genes. They

recruited 88 families with cousin marriages and a high incidence of

autism, from Jordan, Saudi Arabia, Kuwait, Oman, Pakistan, Qatar,

Turkey and the United Arab Emirates.

In some of the families, they found large chunks of missing DNA

regions that followed that recessive rule. The missing regions varied

among families, but they affected at least six genes that play a role

in autism.

Here's why this matters: All the genes seem to be part of a network

involved in a basic foundation of learning — how neurons respond to

new experiences by forming connections between each other, called

synapses.

In the first year or two of life, when autism symptoms appear,

synapses rapidly form and mature, and unnecessary ones are " pruned "

back. A baby's brain is being shaped by its first experiences.

Some earlier research had pointed to the same underlying problem, so

these newly found genes " join a growing list to suggest that autism is

a synaptic disorder, " said Dr. Insel, director of the National

Institute of Mental Health, which helped fund the work.

Copyright © 2008, South Florida Sun-Sentinel