July 10, 2008 -- Surprising findings from a gene study have set the world of
autism research spinning on a new axis.
The new study shows that many of the different genes linked to autism -- and
many of the new autism genes discovered in the course of the study -- are part
of a network that allows a child's brain to build new connections in response
The good news is that a surprisingly large number of these mutant genes
affect the on/off switches that control experience-triggered brain development.
That's much better than missing the genes themselves, says study leader
Christopher A. Walsh, MD, PhD, chief of genetics at Children's Hospital Boston
and an investigator at the Howard Hughes Medical Institute.
"We are encouraged that some of these mutations do not seem to
completely remove the gene altogether, but instead disrupt its on/off
switches," Walsh tells WebMD. "That does offer hope we may be able to
figure out other ways of activating the gene."
It's a big deal, says Thomas Insel, MD, director of the National Institute
of Mental Health.
"We can begin to think of autism as a disease of synapses, of the way
connections are developing in the brain," Insel tells WebMD. "This is
really quite intriguing. It adds another region for science to go after to look
for new targets for either
autism treatment or prevention. It is a very important step."
Autism is a spectrum of different disorders ranging in severity and in
symptoms. But all autism disorders have certain things in common: impaired
social interactions, impaired communication, and stereotyped interests and
The new findings offer a unifying theory, suggesting that many forms of
autism result from specific defects that affect a child's ability to learn and
Genetics plays a major role in autism. The mutations that cause
fragile X syndrome and Rhett's syndrome result in autism. But unlike
diseases such as
cystic fibrosis, the vast majority of autism cases can't be traced to a
single mutation. Instead, a growing number of different genes have been linked
to a growing percentage of autism cases.
"We still don't understand the underlying genetics for more than half
the kids with autism, so we have a long way to go to understand that, and to
understand what non-genetic factors might also contribute," Walsh says.
"We know genetics is very, very important in autism, but we don't know
whether it is the whole answer or not."
The Walsh team's findings are "really exciting," says Margaret A.
Pericak-Vance, PhD, director of the Miami Institute for Human Genomics at the
University of Miami School of Medicine. But she, too, notes that it's far from
the end of the search for the
causes of autism.