10 Years On, Still Much To Be Learned From Human Genome Map04/12/13
FRIDAY, April 12 (HealthDay News) -- As scientists mark the 10th
anniversary Sunday of the completion of the Human Genome Project,
they will note how that watershed effort has led to the discovery
of the genetic underpinnings of almost 5,000 diseases.
And it has made it possible to develop personalized treatments
that have prolonged the lives of many.
But the scientists will also acknowledge that, while the project
has unlocked many mysteries that once shrouded diseases, there's
still much to be learned before new drugs can be developed to
target illness-causing mutations in human DNA.
"What we've learned over the past 10 years is that we're still far from really understanding the complexity of the human genome," said Eric Schadt, chairman of genetics and genomic sciences at Mount Sinai Icahn School of Medicine in New York City. "Human disease is way more complicated than the old view that single hits to single genes cause diseases.
"In most forms of diseases, it's whole constellations of genes operating in networks," Schadt explained. "That becomes a much harder problem. How do you target networks with a single drug?
"We keep learning how much we really don't know and how much further we need to go," he added. "That's the big story."
A decade ago, the Human Genome Project was hailed as a major
milestone because researchers identified all of the nearly 25,000
genes in human DNA and sequenced the 3 billion chemical base pairs
comprising that DNA.
The feat took 13 years and cost close to $3 billion, but the
genetic information gleaned from the project gave scientists the
tools needed to pinpoint how changes in specific genes could
kick-start some diseases.
One of the most tangible benefits of the project has been the
development of ever more sophisticated sequencing technology and a
dramatic lowering of the cost of using that technology.
Today, the cost of sequencing one human genome is closer to
$5,000 and can be done in a day or two, said Dr. Eric Green,
director of the National Human Genome Research Institute in
What that means is that the pace of research, and its attendant
discoveries, has been accelerated.
When the project first began, scientists knew the genetic basis
of about 53 diseases. Today, that number is close to 5,000, Green
noted. That means doctors can now test patients to see if they
carry gene mutations that raise their risk for certain diseases,
and counsel them accordingly on ways they might prevent or delay
illness. There are currently almost 2,000 genetic tests for
specific diseases or conditions, according to the U.S. National
Institutes of Health.
There have also been breakthroughs with some rare diseases.
In 2011, 6-year-old Nicholas Volker became the first child to be
saved by the new technology. He had undergone a hundred surgeries,
including the removal of his colon, as doctors tried to identify
his mysterious bowel disease. Genomic sequencing uncovered a
genetic mutation that could be treated with a bone marrow
transplant consisting of cells from umbilical cord blood.
"Knowing more of the basic genetics that makes up an individual has allowed us to diagnose far more genetic diseases," said Dr. Barbara Pober, a medical geneticist at the Frank H. Netter, M.D. School of Medicine at Quinnipiac University in North Haven, Conn.
Once a diagnosis has been made, doctors can now use gene
sequencing to determine treatment for some diseases. For instance,
breast cancer patients can be tested to see how they will respond
to the drug Herceptin. HIV patients can be tested to determine
their response to the drug abacavir. And those on the widely used
blood thinner warfarin can be tested to determine the most
effective dose, according to the NIH.
The field of pharmacogenetics, still in its infancy, enables
doctors to use a patient's genetic information to figure out which
cancer drugs the patient will best respond to before treatment even
The U.S. Food and Drug Administration now includes genetic
information on labeling for more than 100 drugs, up from just four
10 years ago, Green said.
The goal of developing new drugs to target diseases with genetic
roots, however, will take much longer to realize.
Although the NIH states that there are roughly 350
biotechnological products currently being tested in clinical
trials, new drugs take a decade or more to develop. Not only that,
the knowledge gained from the Human Genome Project has actually
made the field of genetic medicine even more complex. Scientists
are finding that many diseases are triggered by interaction
involving multiple gene variants, making it difficult to design a
treatment that targets all the culprits in a particular
And the complexities don't end there.
Not long ago, scientists discovered that so-called "junk" DNA,
which makes up 98 percent of the genome, is not junk at all but
serves critical regulatory functions.
What's more, about 10 percent of the human genome still hasn't
been sequenced and can't be sequenced by existing technology, Green
added. "There are parts of the genome we didn't know existed back
when the genome was completed," he said.
For more on developments over the past 10 years, visit the
Human Genome Projectwebsite.
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