[extropy-chat] 2nd precursor gene for Alzheimer's
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Mon Jan 15 00:05:07 UTC 2007
Gene for Alzheimer's discovered
Monday, 15 January 2007
Gene for Alzheimer's discovered
A second gene responsible for late-onset
Alzheimer's diesease, a condition affecting
millions worldwide, has been discovered by an
international team of researchers.
CHICAGO: A second gene responsible for the most
common form of Alzheimer's disease has been
identified by U.S. and Canadian researchers.
"The importance of the finding is that it opens
new pathways to explore the cause of the disease,
as well as potential targets for treatment," said
Richard Mayeux of Columbia University's Taub
Institute for Research on Alzheimer's Disease and
the Ageing Brain, and one of the authors of the study.
In genetic studies involving some 6,000
volunteers, the researchers discovered that
variants of the gene SORL1 were more common in
people with late-onset Alzheimer's than in healthy people of the same age.
Additionally, the Alzheimer's sufferers had less
than 50 per cent as much of the protein produced
by SORL1 in their blood compared with the healthy group.
In healthy people, SORL1, which is a 'traffic
cop' regulating the flow of amyloid precursor
protein (APP) inside nerve cells in the brain,
sends APP to a part of the cell where it is recycled.
But in people with the gene variants, the protein
produced by the SOR1 gene appears to drive APP to
another region of the cell where it accumulates
and is degraded into amyloid plaques. Plaques,
according to the researchers, are the abnormal
sticky proteins that gum up the brain of
Alzheimer's victims. "SORL1 is another critical
piece of the Alzheimer's disease puzzle," said Mayeux.
In 1993, U.S. scientists identified the first
genetic marker for late-onset Alzheimer's and two
years later Canadian researchers linked two genes
to the aggressive early-onset form of the disease.
But a decade on, effective treatments for the
progressive brain disease are still lacking, and
the only definitive way to diagnose the illness is by autopsy.
Pharmacuetical companies are scrambling to
develop drugs, many of them targeting the
beta-amyloid protein fragments that are
considered a prime suspect in the nerve cell
death that is a feature of the disease, according
to the Alzheimer's Association in Chicago, Illinois.
Some of those drugs are in clinical trials and
should be on the market in five to 10 years, but
it's a race against the clock as the number of
Alzheimer's cases is predicted to surge with the greying of the population.
In the United States alone, some 4.5 million
people have been afflicted with the
memory-sapping illness, and the prevalence is
expected to double in the next 25 years.
The authors of this study, published today in the
British journal Nature Genetics, said they hoped
that this discovery would speed the search for
drug therapies, and once they are in place, help
identify people at risk for the disease.
"Right now, there are questions about the value
of screening people for the disease, because we
can't do much about it. All that changes if there
are effective therapies that can prevent brain
damage occurring," said co-author Peter St.
George-Hyslop, of the Centre for Research in
Neurodegenerative Diseases at the University of Toronto in Canada.
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