This
is a pretty strong indication that the syndrome retards brain growth directly
and plausibly other parts of the body.
Thus an intervention that counters that should in fact resolve the
problem. At least we now have a starting
point.
It
is a genetic error that simply retards critical physiological development by
failing to express the key growth promoter.
It sounds simple enough that it may lead to a simple solution. We may be lucky.
If
we are, this problem goes away.
Down
syndrome reversed in newborn mice with single injection
Updated Fri 6 Sep
2013, 2:34pm AEST
US researchers have found a way to reverse Down syndrome in
newborn lab mice by injecting an experimental compound that causes the brain to
grow normally.
The study, published in the Science
Translational Medicine journal, offers no direct link to a treatment for humans
but scientists are hopeful it may offer a path towards future breakthroughs.
There is no cure for Down syndrome, which is
caused by the presence of an additional chromosome and results in intellectual
disabilities, distinctive facial features and other health problems.
The team at Johns Hopkins University of
Medicine, in Baltimore, used lab mice that were genetically engineered to have
extra copies of about half the genes found on human chromosome 21, leading to
Down syndrome-like conditions such as smaller brains and difficulty learning to
navigate a maze.
On the day the mice were born, scientists
injected them with a small molecule known as a sonic hedgehog pathway agonist.
'Unexpected benefits' in learning and memory
The compound, which has not been proven safe
for use in humans, is designed to boost normal growth of the brain and body via
a gene known as SHH.
The gene provides instructions for making a protein
called sonic hedgehog, which is essential for development.
"It worked beautifully," said Roger Reeves of
the Johns Hopkins University School of Medicine.
"Most people with Down syndrome have a cerebellum
that's about 60 per cent of the normal size," he said.
"We were able to completely normalise growth of the
cerebellum through adulthood with that single injection."
The injection also led to unexpected benefits in learning
and memory, normally handled by a different part of the brain known as the
hippocampus.
Researchers found that the treated mice did as well as
normal mice on a test of locating a water platform while in a swimming maze.
However, adjusting the treatment for human use would be
complicated, since altering the growth of the brain could lead to unintended
consequences, such as triggering cancer.
"Down syndrome is very complex and nobody thinks
there's going to be a silver bullet that normalises cognition," Dr Reeves
said.
"Multiple approaches will be needed."
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