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Do flawed genes
or environmental triggers
cause autism?
Two experts weigh in
(October
2007 Issue)
By Jennifer Chase Esposito
This past spring, scientists released results of a study that found
100 genetic flaws out of the body's some 25,000 genes might cause
autism, giving credence to autism being a genetic condition.
Additional research released in August found that autism can be
caused by both genes and environmental triggers, with results convincing
enough for $7.5 million in federal funding to be earmarked for autism
research, $2 million of which will be set aside for another study
that would try to track - more closely and as early as in the womb
- possible environmental triggers for autism.
So the autism theory of evolution continues: genetics vs. environmental
triggers? Who is right? Or is everyone?
"I think that genetics play a very large role in probably every
kid with autism," says Rowland Barrett, Ph.D., director of Bradley
Hospital's Department of Autism and Developmental Disabilities in
R.I. "I think the problem is that we don't know what autism is.
We only know what autism looks like. As we unravel this mystery,
we're going to find out there's truly a genetic form of autism that
environmental triggers have nothing to do with and that we have
to look at things that mimic autism that are a result of triggers."
"I think most people who work in the field, whether clinicians
or research, appreciate that there are two seemingly diverse autistic
populations," says Barrett. One, he says, is the population of patients
who have a close or distant relative with either autism or a type
of "autism simplex," as it's sometimes referred, who don't share
any environmental factors.
Then there are those complex cases where no family member shares
symptoms of autism or is exposed to the same environmental factors.
It's especially in those complex cases where there's no real way
to know the origins of the autism.
Barrett believes that most researchers think autism is genetic:
there are too many children who have cousins and family members
from different parts of the country with different environmental
factors, for it not to be truly a neurological disorder.
William Ahearn, Ph.D., BCBA, director of research at New England
Center for Children in Southborough, Mass., one of the leading autism
centers in the country, notes that "recent studies of the genetics
of autism have showed some promise in helping to reveal the genes
or types of genetic variables (deletions or repletions) that seem
to be involved in autism."
But Barrett reminds that even Autism Speaks - the nation's number
one advocacy group for parents of children with autism - has its
own genome project, hedging that the causes are purely genetic.
Does it really matter whether a child is autistic because of genetics
or their surroundings? If you're blind from a chemical explosion
or blind from birth, says Barrett, you still have to adapt to life
as a blind person.
"[But] whether it's genetics or [a child is] exposed to environmental
triggers...I think it does matter," he says. "A least in terms of
future prevention. If you wear protective eyewear, you're not going
to go blind from an explosion."
On the other hand, he says, the Dianthethis Stress Model - a longstanding
theory in developmental psychopathology - says that although you
may have a high or low constitution for a disorder, you may have
high or low environmental stresses threshold that could trigger
a condition.
"As with any question relating nature (genes) and nurture (environment),
there is an explicit lack of understanding of the inherent interplay
between these two influences," says Ahearn. "Genes are not blueprints
but are more like recipes. That is, genes are activated in an environment
and we speak of the phenotypic expression that results from this
interactive process."
One thing that really has been proven, says Barrett, is that Thermasol
did not cause autism in children." It's been out of virtually everything
since 1990. Now it's not even in flu shots. But rates continue to
go up.
Ahearn agrees. "Though people suspect vaccines of inducing autism,
all sound scientific evidence refutes this suspicion."
As for the announcement of the millions in funding with some $2
million earmarked for environmental study, Barrett believes it's
the prudent thing to do. "If you're going to study the origins,
going to have to study genetics, it's not nearly enough money. But
it's good seed money." Ahearn agrees that research is necessary,
but similar to parents who desire more resources than research,
he believes the disparity between funding for etiological research,
for treatment research and funding for service provision is great.
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