Oct 31 2003
Scientists believe they may be able
to one day reverse some of the symptoms
of Down's Syndrome.
and Swiss-based researchers have
found a gene they think is responsible
for mental retardation in Down's.
The team hope that a
drug could now be discovered to
"reactivate" a part of
brain that does not work properly
in patients with the genetic disorder.
However, they stress
that their work is at an early stage,
and any treatment would be some
The human cell nucleus
contains 23 pairs of chromosomes,
which carry genetic information
necessary for developing and running
the body correctly.
In Down's syndrome,
the baby carries an extra copy of
chromosome 21, and its presence
interferes with several important
Too many genes
Unlike many gene defects,
which happen because a key gene
is missing, the Down's defects arise
because they have an extra copy
of certain genes on the third chromosome
We definitely think we are on the
right track to restoring memory
and learning in individuals with
Professor William Mobley, Stanford
This means that they are producing
too much of certain body chemicals,
throwing finely tuned mechanisms
which govern the development and
function of vital organs into disarray.
Children and adults
with Down's have a distinctive facial
appearance with protruding eyes
More importantly, they
often have heart defects, are generally
more prone to heart disease, cannot
regulate temperature well in infancy,
and are vulnerable to infections.
On top of this, most
children with Down's have varying
degrees of mental retardation.
The research team, based
both at Stanford University in California
and the University of Geneva, claims
to have found a gene on chromosome
21 which plays a role in retardation.
In experiments in mice
which have a similar genetic fault
- and which share many genes with
humans - they have found a gene
which appears to hinder the transport
of an important brain chemical into
a certain part of the forebrain.
This has already been
linked with retardation.
Reversal of fortune
Chemistry and Industry
reports that this gene could now
be the target for drugs to "downregulate"
the action of the extra gene - although
these drugs are some time away.
Remarkably, there is
some hope that a drug to reverse
this gene defect could actually
reverse retardation to some degree
even in adults.
This area of the forebrain
does not require new brain cells
- it already has cells, but they
are simply not working properly.
The theory is that a
drug to restore their proper activity
could have a marked effect.
Professor William Mobley,
from Stanford University, said:
"We definitely think we are
on the right track to restoring
memory and learning in individuals
with Down's syndrome.
"With the perfect
drug at the right dose, we can reduce
protein production by the extra
copy of the gene.
"We think that
this could reverse mental retardation."
No certain improvement
However, this is far
from certain, as no-one knows how
newly-reactivated neurons would
behave, or how they would fit into
the wider workings of the brain.
Professor Mobley said
that it was possible there would
be absolutely no effect whatsoever.
Dr Jonathan Cooper,
from the Institute of Psychiatry,
told BBC News Online: "If it's
a single gene involved in the degeneration
of these cells, then it should be
possible to target it, although
this may be technically complicated
"However, if you
can restore these cell populations,
it would be important to know that
they are fully functional, which
presently remains unclear"
"This is a very
good research team and this idea
shows great potential - although
it is at a very early stage.
"There is likely
to be some way to go before this
can translate into treatments in
A spokesman for the
Down's Syndrome Association told
BBC News Online: "The findings
of William Mobley and his team are
interesting and we would welcome
anything that improves the lives
of people with Down's syndrome.
although this work appears to be
at a very early stage, with no effective
treatments likely in the foreseeable
future, we plan to be in communication
with the team to see if there is
any opportunity for us to give our