分类： BSD
2010-06-18 14:51:19
New research reveals that genetic glitches are linked to autism, a finding that might eventually lead to strategies to treat one of the most mysterious maladies in medical science.
An international team of researchers, coordinated by a Stanford scientist, announced Wednesday that it has identified dozens of genetic errors linked to five to ten percent of autism cases. Those errors — caused by missing or duplicated pieces of DNA — are believed to interfere with the brain's messaging system.
"Autism can be devastating to families, and we need better treatments," said Dr. Joachim Hallmayer of the Stanford Autism Center at Packard Children's Hospital. "The hope is that if we know which genes and genetic pathways are implicated in autism, then we can target them more specifically with treatment.".
Hallmayer organized the 120-member collaborative Autism Genome Project, which studied the genetic data of 1,000 autistics from 11 different nations. The quest for genes that underlie autism, a major disorder of cognition, has been long and frustrating.
Twin and familial studies have shown the condition to be highly genetic — yet no one has identified a single culprit. Scientists have debunked theories that autism is caused by vaccines or bad parenting.
Autism is one of the more urgent health problems of the 21st century. In California, from 1987 to 1998, he number of children getting services for autism tripled. Then between 1998 and 2002 the number doubled.
Scientists with the Autism Genome Project performed gene scans of individuals with autistic spectrum disorder, a condition marked by social isolation, speech problems and strange, repetitive movements. Those scans were analyzed and compared to those of non-autistic individuals.
They found that individuals with autism carry about 1.7 times more microscopic errors, also known as deletions or "insertions" in their genome. Some of the errors seem to be inherited from parents. Others are new, found only in affected offspring but not parents.
The genes affected by the errors are known to be linked to intellectual disability.
Funded by the Autism Speaks advocacy group and reported Bug Detectors Wednesday in the journal Nature, the findings support an emerging consensus among scientists that the condition — like human cognition itself — is extremely complicated.
While some cases of autism are caused by multiple and varied genetic disruptions, other could be caused by simple one-letter DNA typos. Still others may be influenced by a tangle of environmental circumstances.
"It is much more complex than we thought," said Hallmayer.
But even if the causes are vast and varied, they may all disrupt just a few critical biochemical or physiological pathways, he said. Those pathways — affecting speech, behavior and cognition — could be targets of therapy.
A complete understanding of autism will require an even larger analysis of affected individuals, Hallmayer added.
"Piece by piece, we are discovering genetic mutations that can cause autism," said Andy Shih, Autism Speaks vice president for scientific affairs. "These genetic findings help us understand the underlying biology of autism."
