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Scientists try to reverse Down syndrome -

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Scientists try to reverse Down syndrome

Madeleine Genner reported this story on Thursday, November 19, 2009 12:18:00

ELEANOR HALL: US researchers say they've found a way to reverse the symptoms of Down syndrome.

It's estimated that 25, 000 Australians have the disorder. Now scientists in the US say tests on
mice with a similar condition to Down syndrome have shown signs of improvement and the researchers
hope that it might be an important first step in finding ways to treat the disorder.

Madeleine Genner has our report.

MADELEINE GENNER: At birth children with Down syndrome aren't developmentally delayed. But that
soon changes.

Dr Bill Warren is an associate professor at the Comparative Genomics Centre at James Cook
University.

BILL WARREN: Down syndrome as most people are aware is a problem with the chromosomes where a child
has been conceived with three copies of the 21st chromosome. So they have an extra 300 or so genes
and those genes play many different roles around the body.

And part of the problem with Down syndrome is that those extra genes lead to a problem with
contextual learning and some memory defects.

MADELEINE GENNER: Now scientists at the Stanford University School of Medicine and the Lucile
Packard Children's Hospital say they might have uncovered a way of partially reversing the effects
of Down syndrome.

Ahmad Salehi is a member of the research team.

AHMAD SALEHI: What we believe is that there is always for Down syndrome, there is a window of
opportunity for us to intervene. There's a time where the brain is very similar to a brain of a
person with two chromosomes of 21. And if we intervene early enough we could, not entirely reverse
the process, but at least prevent further deterioration of the cognitive dysfunction in people with
Down syndrome.

MADELEINE GENNER: Dr Salehi says his tests on mice have examined how the brain malfunctions in Down
syndrome. He says they prove that the ability to process information doesn't fail in every aspect.

For instance people with Down syndrome struggle with spatial information or the ability to navigate
through something like a shopping centre but they are much better at remembering colours, sounds
and other sensory cues.

Dr Salehi says boosting a neurotransmitter known as norepinephrines does improve a mouse's ability
to process information by strengthening the links between different parts of the brain.

He hopes it might do the same in humans.

AHMAD SALEHI: It's always very difficult to take, to take the idea from a mouse and try to
translate it into humans but that is the idea.

MADELEINE GENNER: Dr Salehi says the research isn't necessarily a cure but it could be an important
first step. He says more work is needed before human trials commence.

AHMAD SALEHI: The cure would be when we identify those genes one by one. That's what we are doing.

We are trying to be making different mouse models that have, let's say one mouse has 100 genes. The
other mouse has 90 genes. The other mouse has 80 genes. And then comparing which genes play the
major role in, let's say cognitive disabilities in people with Down syndrome.

There's always hope that once we prove that this system, this strategy works then there is a hope
that one day we could try to restore norepinephrinergic system in humans.

MADELEINE GENNER: Dr Bill Warren agrees that the research is in its early stages but he says the
findings are promising.

BILL WARREN: It's certainly a very exciting results. I mean we've been studying Down syndrome for
many years and have had very little in the way that we can intervene to try to make the symptoms
less severe or try to improve the situation.

And let's keep in mind that this is a preliminary study and it has been done using a mouse model
for Down syndrome. So a lot of work still needs to be done and the exact mechanism which need to be
found out, perhaps the chemical norepinephrine which has many roles in the body may not be the best
molecule to use to intervene. But certainly it is very exciting news.

ELEANOR HALL: And that's Dr Bill Warren from the Comparative Genomics Centre at James Cook
University ending that report by Madeleine Genner.