Researchers from around the
world have launched a three-year project aimed at identifying
genes that are responsible for such common illnesses as
cancer, heart disease and diabetes. The effort is an outgrowth
of the Human Genome Project.
The international Human Genome Project produced a genetic
road map unveiled two years ago, describing the arrangement of
chemical building blocks in each cell that regulates how
humans function. But because the genome, or collection of
genes, is so vast, researchers can only guess where to look
within the blueprint for proteins that may play a role in
illness.
The $100-million International HapMap Project, described as
the next phase of the Human Genome Project, is a refinement.
Fifteen teams of researchers in the United States, China,
Canada, England, and Japan will attempt to identify so-called
haplotypes, or groups of genes that are passed from one
generation to the next.
David Altshuler of the Whitehead Center for Genome Research
at Harvard Medical School in Cambridge, Massachusetts, heads
one of the research groups working on HapMap.
Dr. Alschuler says one of the main goals of the Human
Genome Project is to help understand the inherited basis of
human disease, that is, why some people get diabetes or heart
disease and others do not. That means cataloging the minute
genetic differences between individuals.
Researchers think there are about ten-million genetic
differences throughout the human genome that play a role in
disease. One way to find the haplotypes is to search for them
individually, an extremely time-consuming and expensive
project. Or Dr. Altschulter says researchers can look for
clusters or blocks of haplotypes and construct a map.
"The people who would get one particular variation would
have a whole series of variations next to each other called a
haplotype that they would inherit in common," he said. "And so
in a sense the haplotype map is just a way to simplify this
process of genetic studies."
Experts say that 99.9 percent of the population is
genetically identical, having emerged from Africa between
10,000 and 100,000 years ago. It's the .1 percent difference
in our DNA, or genetic material, that researchers focus on to
learn more about disease.
Researchers think they will be able to create a map of all
ten million haplotypes in the human genome testing between 200
to 400 blood samples drawn from Europe, Africa and Asia.
Tom Hudson, the head of Montreal's Genome Center at McGill
University in Canada, which will analyze ten percent of the
data for the HapMap project, says researchers will pinpoint
blocks of haplotypes, or genetic markers, that disease
researchers can consult once the map is finished.
"What we're going to identify is the right set of markers
which can be used to test every block across the genome," he
said. "So, if someone works in hypertension or diabetes, they
need to go and test these markers that we've developed in
terms of this project in their cohorts of people with
hypertension compared to people without hypertension, and the
same thing for diabetes and cancer and so on."
The Whitehead Institute's David Altschuler would like to
see peoples' genetic susceptibility to disease put on the same
mantle as the risk due to environmental factors, such as the
increased likelihood that they'll get lung cancer if they
smoke cigarettes. Dr. Altschuler thinks HapMap will do that.
"What we're talking about here actually is genetic
exposure," he said. "That is, in addition to the environmental
exposures that people have studied and will continued to
study, we're saying here are the common genetic variations
that might influence disease. And they'll be used in the same
kind of association studies, epidemiologic studies, to ask are
any of these variations correlated with disease. And if they
are, then they become important targets for developing
diagnostics and new therapies."
The HapMap project is scheduled to take three years to
complete, although researchers hope to finish it sooner.
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