A Genetic Clue to Why Autism Affects Boys More

May 20, 2009

Here is something published in Time . what do we make of this?

TIME

By ALICE PARK Alice Park - Wed May 20, 6:20 am ET

Among the many mysteries that befuddle autism researchers: why the disorder

affects boys four times more often than girls. But in new findings reported

online today by the journal Molecular Psychiatry, researchers say they have

found a genetic clue that may help explain the disparity.

The newly discovered autism

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-risk gene, identified by authors as CACNA1G, is more common in boys than in

girls (why that's so is still not clear), and the authors suggest it plays a

role in boys' increased risk of the developmental disorder. CACNA1G, which

sits on chromosome 17, amid other genes that have been previously linked to

autism, is responsible for regulating the flow of calcium into and out of

cells. Nerve cells in the brain rely on calcium to become activated, and

research suggests that imbalances in the mineral can result in the

overstimulation of neural connections and create developmental problems,

such as autism and even epilepsy, which is also a common feature of autism.

(

<http://us.rd./dailynews/time/hl_time/storytext/08599189975600/3207

3688/SIG=12kvbetpo/*http:/www.time.com/time/specials/packages/article/0,2880

4,1893554_1893556,00.html> See six tips for traveling with an autistic

child.)

" Our current theories about autism suggest that the disorder is related to

overexcitability at nerve endings, " says Geri Dawson, chief science officer

of Autism Speaks, an advocacy group that provided the genetic data used by

the study's authors. " It's interesting to see that the gene they identified

appears to modulate excitability of neurons. "

For the new study, researchers at the University of California, Los Angeles

(UCLA), combed the genetic database of the Autism Genetic Resource Exchange

(AGRE), a resource of DNA from 2,000 families with at least one autistic

child. The scientists focused on the more than 1,000 genetic samples of

families in which at least one son was affected by the disorder, prompted by

the results of an earlier study using the same database, which identified a

rich autism-related genetic region on chromosome 17 that contained genetic

variants more common in boys than in girls. While nearly 40% of the general

population has the most common form of CACNA1G, one variant of the gene was

more prevalent in autistic boys, researchers found. " There is a strong

genetic signal in this region, " says Dr. Geschwind, director of

UCLA's Center for Autism Research and Treatment and one of the study's

co-authors. " But this gene doesn't explain all of that signal or even half

of it. What that means is that there are many more genes in this region

contributing to autism. " (

<http://us.rd./dailynews/time/hl_time/storytext/08599189975600/3207

3688/SIG=11pkhspim/*http:/www.time.com/time/photoessays/2006/autismschool/>

See pictures of inside a school for autistic children.)

That's not surprising for a disorder as complex as autism - actually, a

spectrum of developmental disorders involving impairment in language, social

behavior and certain physical behaviors - with symptoms that range widely in

number and severity. So far, studies have linked a handful of genes, all of

which play a role in the way

<http://us.rd./dailynews/time/hl_time/storytext/08599189975600/3207

3688/SIG=1225o0np0/*http:/www.time.com/time/magazine/article/0,9171,1191843,

00.html> nerve cells connect and communicate, with autism spectrum

disorders. It's likely not only that a large number of genes contribute to

the disorder, but also that a different combination of genes - as well as

unique interactions between genes and environment - are responsible for each

individual case of autism.

So it's certainly a daunting challenge to begin teasing out the individual

genes that may contribute to autism, as the UCLA team has with CACNA1G, but

databases like AGRE make the job slightly easier. The next step will be to

try to use known autism genes to help develop screening tools or early

interventions. " We are going to have a much better understanding of the

causes of autism over the next five to 10 years, " says Dawson. " We're in a

period of great discovery. "

<http://us.rd./dailynews/time/hl_time/storytext/08599189975600/3207

3688/SIG=11cm8egb0/*http:/www.time.com/time/picturesoftheweek> See TIME's

Pictures of the Week.

<http://us.rd./dailynews/time/hl_time/storytext/08599189975600/3207

3688/SIG=12k70eqgn/*http:/www.time.com/time/specials/packages/article/0,2880

4,1847616_1847615,00.html> See the most common hospital mishaps.

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