Forum Bioethik INFO/   Human Genetics Alert

December 20, 2001



Thursday, 20 December, 2001, 05:20 GMT

The tips of chromosome 20 are visible stained red (Molecular Cytogenetics,
Wellcome Trust Sanger Institute)
By BBC News Online's Helen Briggs

Another chapter in the human book of life has been published.
Scientists have deciphered the complete genetic instructions of a third
chromosome, one of the 24 bundles of DNA that carry our genetic material.
The latest to be finished, chromosome 20, is the largest so far.
The discovery could shed light on why some people are more likely to develop
common diseases such as diabetes, obesity or eczema because of their genes.
It could also give an insight into variant Creutzfeldt-Jakob disease (vCJD),
the human form of mad cow disease. The gene that appears to make some people
more susceptible to contracting vCJD is found on chromosome 20.
Disease 'quest'
The work is part of the ongoing Human Genome Project, an international
effort to sequence (read) the genetic make-up of humans.
One third of the work was carried out in the UK at the Wellcome Trust Sanger
Institute near Cambridge.
Dr Mike Dexter, Director of the Wellcome Trust, said: "This is one more
completed chapter of our genomic anatomy textbook - medical research will be
using this information for decades to come in its quest to tackle our common
"Once again, we are seeing the fruits of the two key commitments of the
Human Genome Project: to make the sequence freely available and to produce a
quality finished sequence."
'Gold standard'
The first draft of the entire human genome, the instructions needed to make
a human being, was unveiled in the spring.
The work was carried out by two groups, the publicly funded International
Human Genome Sequencing Consortium, and a private US company, Celera
Scientists are now trying to fill in some of the gaps in the data to come up
with a "gold standard".
Two human chromosomes have already been completed to this standard. The
sequence of chromosome 22 was revealed two years ago. This was followed, in
May 2000, by chromosome 21.
The completion of chromosome 20 is significant for a number of reasons:
It is the largest chromosome to be finished so far. Nearly 60 million
genetic "letters" have been sequenced and there are only four gaps
It is also the first chromosome to be sequenced that has a typical structure
of long and short arms
More than 720 genes have been found. They include the genes that underpin
multi-factorial diseases such as diabetes, obesity and childhood eczema
Intriguingly, some people (37%) have an extra chunk of DNA in chromosome 20
and could have an extra copy of a specific gene of unknown function.
Dr Panos Deloukas, leader of the project at the Sanger Institute, said the
discovery was another important step towards understanding the link between
genes and diseases.
"The next step is to start understanding the functions of the genes," Dr
Deloukas told BBC News Online.
"The sequence, the genes and the variations between people in the population
is the tool to start dissecting complex common diseases like diabetes,
obesity and eczema."
The chromosome 20 results are published in full in the journal Nature.

Other related stories

Chromosome Veers Off Genome Map


Tuesday December 18 5:52 PM ET


By Merritt McKinney

NEW YORK (Reuters Health) - An experimental form of gene therapy holds
promise for speeding the regrowth of hair after chemotherapy, new research
By boosting levels of a gene called ``sonic hedgehog,'' or Shh, New York
researchers saw signs of the growth of new hair in mice treated with
The gene ``seems to be the master switch for making the hair follicle
grow,'' the study's lead author, Dr. Ronald G. Crystal at the Weill Medical
College of Cornell University in New York, told Reuters Health in an
About 85% of people who undergo chemotherapy to treat cancer lose at least
some of their hair. Hair usually takes 3 to 6 months to grow back after
treatment, but it fails to return in a small group of cancer patients.
The problem of hair loss may seem insignificant in the face of a cancer
diagnosis, but hair loss can be devastating, according to Crystal, since it
is a visible sign of a disease that is otherwise hidden. He noted that
several studies have shown that chemotherapy-induced hair loss can have ``a
real psychological impact.''
Crystal explained that chemotherapy does not destroy hair-producing
follicles, but it does damage them temporarily.
``The hair follicles are still there,'' he said. ``They just get beat up a
Crystal and his colleagues have been working to develop a way to use Shh to
speed hair growth after chemotherapy. This gene is involved in the formation
of several organs, including the brain, heart, lung, gut, skin and skeleton,
but it also seems to be involved in getting hair follicles to grow.
Crystal's team used a harmless virus to deliver extra amounts of Shh to mice
with chemotherapy-induced hair loss.
The gene therapy appeared to work, stimulating hair follicles around the
injection site, the researchers report in the December 19th issue of the
Journal of the National Cancer Institute.
In a group of 7-week-old mice that received the treatment, researchers
observed that the hair follicles around the site of the injection entered
the growth phase of development sooner than hair follicles in animals that
did not receive the boost of Shh. In mice that received gene therapy, but
not in untreated mice, skin around the injection site darkened, which is a
sign that hair is growing.
Gene therapy also achieved similar results in younger mice, Crystal and his
colleagues report. The growth of hair follicles was accelerated in nearly
all of a group of 3-week-old mice, but in none of the mice that received the
virus without the sonic hedgehog gene or no treatment at all.
The therapy gives hair follicles a ``genetic boost to get them growing
again,'' Crystal said.
The next step, the New York researcher said, is to consider whether to test
the therapy in human clinical trials. According to Crystal, ``there's a good
chance'' that such trials could begin within a few years.
SOURCE: Journal of the National Cancer Institute 2001;93:1858-1864.


One News
Fear that humans could be cloned in New Zealand is prompting an urgent law
The government is rushing through legislation to ban human cloning, the
genetic engineering of human babies and putting animal material into humans.
The changes are being tacked on to legislation being debated by parliament
on Thursday.
But the Greens say that this may not be enough to prevent genetically
engineered humans being developed in New Zealand.
Italian doctor Severino Antinori and rival doctors, say they are close to
cloning a human child.
"There is always the possibility, I heard him say he (Antinori) was looking
for a beautiful country to clone children in, people said it could be New
Zealand, we don't have any legislation to stop him at the moment, so this is
stop gap legislation," said Labour List MP Dianne Yates.
Yates says the law is being rushed through but will expire in two years to
allow for more consultation.
The new law will ban putting animal parts into human beings. It also outlaws
genetically engineering human babies and covers cloning.
But the law does allow a minister to authorise an exemption, and that is
what has got the Greens worried.
"I'm appalled at the idea that the Minister is acting alone without any
public process of submissions or hearings could give consent to genetically
engineered human babies," said Jeanette Fitzsimons Greens, co-leader.
But scientist Professor Bob Elliot is angry for other reasons, the Health
Ministry has turned down his application to put pig cells in diabetics as a
possible cure.
Elliot says the new law is an attempt to head off his legal challenge.
"In New Zealand we have this incredible backward move banning what is going
to be a very very valuable technique," Elliot says.
Officials will meet with he Greens on Thursday in a bid to win their
Published on Dec 19, 2001

December 18, 2001
New York Times


Dr. Brigid Hogan has never worked with human embryonic stem cells  her
expertise is with mouse cells. But patients with virtually every sort of
chronic disease have found her, and they plead for help.
"I even hear from patients whose fathers have lung cancer," said Dr. Hogan,
a professor at Vanderbilt University School of Medicine. "They have a whole
slew of problems they think can be treated. They think stem cells are going
to cure their loved ones of everything."
If it ever happens, it will not happen soon, scientists say. In fact,
although they worked with mouse embryonic stem cells for 20 years and made
some progress, researchers have not yet used these cells to cure a single
mouse of a disease.
Scientists say the theory behind stem cells is correct: the cells, in
principle, can become any specialized cell of the body. But between theory
and therapy lie a host of research obstacles. Though not often discussed in
public forums, the obstacles are so serious that scientists say they foresee
years, if not decades, of concerted work on basic science before they can
even think of trying to treat a patient.
Yet as excitement over stem cell research built over the summer, and surged
again with recent reports of experiments with human cloning, scientists and
doctors became deluged with calls from desperate patients who saw salvation
around the corner. Somehow this research has come to be seen as the great
hope for medical science. How, scientists ask, did expectations grow so
Though some say the news media overplayed the issue, some scientists say the
problem lies within themselves. The crucial questions involve basic
research, the sort supported by federal funds and conducted in universities.
But with calls by some politicians to ban the work, and to bar any use of
tax money to pay for it, scientists say they feel obliged to stress how
important the research is. And, some say, they now fear they may have
promised too much.
"We're being forced into taking extreme positions by the whole need to try
and convince people of the need to go ahead," Dr. Hogan said.
Dr. Gail Martin, a mouse stem cell researcher at the University of
California at San Francisco, said: "The expectations have been raised a
little higher than perhaps is appropriate. It became politicized and tied up
in the abortion debate." But, as the exaggerations and talk of revolutionary
treatments continued, few made concerted efforts to set the record straight.
And some small biotechnology companies continued to promise quick cures.
One problem is simply to find a way to get stem cells to grow into the types
of cells that are needed, and not a mixture of cells.
Scientists know this is a thorny problem, but their views were not widely
heard when the public and politicians seemed to assume that it was easy to
grow any tissue type desired from embryonic stem cells. In fact, no one has
been able to do this even with mouse cells.
Using stem cells to cure diabetes, for example, would mean converting them
to islet cells, specialized cells of the pancreas that secrete insulin. And
then the new islet cells would have to be protected from the underlying
disease process that caused the diabetes in the first place. The science is
not even close.
"Do we know how to make islet cells? No. Do we know how to make kidney
cells? No," said Dr. Shirley M. Tilghman, a mouse molecular geneticist, who
is the president of Princeton. "You can go on and on," she said.
"In the early days there was a cottage industry of trying to get them to do
different things," Dr. Tilghman said. But the stem cells would never become
just one type of cell, developing instead into mixtures of specialized cell
Few outside the field realize the difficulty of working with stem cells, Dr.
Martin and others said. When mouse stem cells grow in the laboratory, she
said, some of them spontaneously change, with chunks of genetic material
moving from place to place on chromosomes. She said that if such changes
gave cells even a 5 percent growth advantage in the laboratory, the altered
cells completely took over the stem cell population within three
generations. And if such cells were put into patients, they could cause
Even if all the other problems with stem cells are solved, researchers will
face another problem. The body's immune system will see the new cells as
foreign tissue and reject them. The only sure way to prevent this is to take
powerful immune suppression drugs for a lifetime, trading insulin
injections, for example, for immune suppression.
The problem would be avoided if the stem cells were derived from an embryo
that was a clone of the patient  the stem cells of such an embryo would be
genetically identical to the patient's cells. But cloning has its own
problems. Not only do many politicians and religious leaders find it
ethically abhorrent to create a clone and then destroy it as an embryo to
extract its stem cells, but no one has yet come near getting the process to
One company, Advanced Cell Technology, recently announced its first attempts
to create human embryos by cloning. The company failed  its embryos never
grew or developed anywhere near a point where they would contain stem cells.
That normally occurs after about five days, when the embryo becomes a sphere
with a ball of stem cells inside. Most of the company's embryos died without
dividing even once, although one made it to an amorphous clump of six cells.
In animals where cloning has succeeded, it remains very inefficient, often
requiring 100 or more eggs to get a single viable clone.
Finally, researchers must get replacement cells derived from stem cells to
integrate into the body's complex machinery and fill in the blanks left by
diseased or dying cells. That task may pose its own problems, as scientists
found when they tried to supply fetal brain cells to patients with
Parkinson's disease. In some patients, the fetal cells apparently grew too
well. They pumped out too much of the brain chemicals, and there was no way
to remove the cells or turn them off.
But these cautionary findings were seldom mentioned when advocacy groups for
patients with various disease took up the cause, even though researchers
expressed little optimism for cures any time soon, if ever. The task of
getting stem cells to develop into specialized nerve cells and then getting
those cells to repair the damage in the disease is well beyond today's
science, experts say.
"I have no idea how someone expects that you will inject neuroblasts and
they will run all over the brain and replace your sick and dying neurons in
Alzheimer's disease," said Dr. Davor Solter, a mouse stem cell researcher
who directs the Max Planck Institute in Germany.
Dr. Martin, who is a co-discoverer of mouse embryonic stem cells and the one
who named them, added, "There are a gazillion issues."
That is not to say that the issues will never be resolved. Dr. Steen
Willadsen, a Danish scientist and a cloning pioneer who saw the impossible
happen in his field, said demand for stem cell therapies was so great that
scientists would make it happen, sooner or later.
But Dr. Martin and others say they worry about the short term, concerned by
how the public will react when it becomes clear that stem cells are not an
immediate answer for suffering patients. She and others say they are bracing
themselves for a backlash when treatments fail to materialize.
"There's almost certainly going to be a backlash," said Dr. James A.
Thomson, the University of Wisconsin scientist who first isolated human
embryonic stem cells. "These are novel, unproven therapies. I believe there
is tremendous promise, but it's going to take years to develop therapies."
He said, however, that the media, not scientists, were at fault for the
exaggerated promises.
"I blame the press," Dr. Thomson said. "It is very compelling to be able to
make new body parts. It captures the imagination."
But Dr. Inder Verma, a gene therapy researcher at the Salk Institute in San
Diego, said scientists set off the frenzy with their own hyperbole. And, he
said, he has seen this sort of process unfold once before, with disastrous
Gene therapy, Dr. Verma said, had the same sort of promise attached to it
two decades ago. In that field, too, scientists predicted too much too soon.
When gene therapy failed, many turned against it. Stem cell therapy is
heading in the same directions, Dr. Verma said, and some scientists are
beginning to worry.
"We started it," Dr. Verma said, speaking of the debate. Now, he said, "we
withdraw from it because we realize it is going out of control."
Yet, he said, this time, with abortion politics entwined in the story, the
public backlash may be far worse than it was with gene therapy.
"In five years, if it doesn't work out, people will turn to us and say, `You
divided the nation,' " Dr. Verma said.


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