By Lisa M. Krieger lkrieger@mercurynews.com
Dozens of different gene defects are linked to autism, according to two major new studies of the developmental disorder led by UC San Francisco scientists and involving more than 50 laboratories worldwide.
The mutations -- which may work alone or in combination -- are all connected by their roles in a few basic molecular pathways, which could be targets for future treatments, according to the two studies, published Wednesday in the journal Nature.
"The genes that we identify are critically important clues about the underlying biology of autism, which we really need to understand to know what is going wrong," said Dr. Matthew W. State, UCSF professor of psychiatry, a co-leader of one study and a key participant in the second.
Not all cases of autism have a gene-based beginning. Growing brains can also be influenced by environmental events.
In many cases, a combination of factors may be involved, he said.
While a rare few of the newly detected mutations are inherited from the parents' genomes, most families do not have a family history of the disorder.
Rather, these mutations arose during the creation of a father's sperm cell or mother's egg cell, they found.
The scientists tied mutations in more than 100 genes to autism. Sixty of these genes met a "high-confidence" threshold, indicating that there is a greater than 90 percent chance that mutations in those genes contribute to autism risk.
The finding that autism can result from mutations in so many genes suggests that it is not a single condition, but rather an umbrella term for patients with similar sets of conditions.
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San Francisco scientists find autism linked to dozens of genetic mutations