Excerpt from themarketbusiness.com
A group of biologists was alarmed with the use a new genome-editing
technique to modify human DNA in a way that it can become hereditary.
The biologists worry that the new technique is so effective and easy to
use that some physicians may push ahead with it before its safety can be
weigh up. They also want the public to understand the ethical issues
surrounding the technique, which could be used to cure genetic diseases,
but also to enhance qualities like beauty or intelligence. The latter
is a path that many ethicists believe should never be taken.
“You could exert control over human heredity with this technique, and
that is why we are raising the issue,” said David Baltimore, a former
president of the California Institute of Technology and a member of the
group whose paper on the topic was published in the journal Science.
Ethicists have been concerned for decades about the dangers of
altering the human germ line — meaning to make changes to human sperm,
eggs or embryos that will last through the life of the individual and be
passed on to future generations. Until now, these worries have been
theoretical. But a technique invented in 2012 makes it possible to edit
the genome precisely and with much greater ease. The technique has
already been used to edit the genomes of mice, rats and monkeys, and few
doubt that it would work the same way in people.
The new genome-editing technique holds the power to repair or enhance
any human gene. “It raises the most fundamental of issues about how we
are going to view our humanity in the future and whether we are going to
take the dramatic step of modifying our own germline and in a sense
take control of our genetic destiny, which raises enormous peril for
humanity,” said George Daley, a stem cell expert at Boston Children’s
Hospital and a member of the group.
The biologists writing in Science support continuing laboratory
research with the technique, and few if any scientists believe it is
ready for clinical use. Any such use is tightly regulated in the United
States and Europe. American scientists, for instance, would have to
present a plan to treat genetic diseases in the human germline to the
Food and Drug Administration.
The paper’s authors, however, are concerned about countries that have
less regulation in science. They urge that “scientists should avoid
even attempting, in lax jurisdictions, germ line genome modification for
clinical application in humans” until the full implications “are
discussed among scientific and governmental organizations.”
Though such a moratorium would not be legally enforceable and might
seem unlikely to exert global sway, there is a precedent. In 1975,
scientists worldwide were asked to refrain from using a method for
manipulating genes, the recombinant DNA technique, until rules had been
established.
“We asked at that time that nobody do certain experiments, and in
fact nobody did, to my knowledge,” said Baltimore, who was a member of
the 1975 group. “So there is a moral authority you can assert from the
U.S., and that is what we hope to do.”
Recombinant DNA was the first in a series of ever-improving steps for
manipulating genetic material. The chief problem has always been one of
accuracy, of editing the DNA at precisely the intended site, since any
off-target change could be lethal. Two recent methods, known as zinc
fingers and TAL effectors, came close to the goal of accurate genome
editing, but both are hard to use. The new genome-editing approach was
invented by Jennifer Doudna of the University of California, Berkeley,
and Emmanuelle Charpentier of Umea University in Sweden.
Their method, known by the acronym Crispr-Cas9, co-opts the natural
immune system with which bacteria remember the DNA of the viruses that
attack them so they are ready the next time those same invaders appear.
Researchers can simply prime the defense system with a guide sequence of
their choice and it will then destroy the matching DNA sequence in any
genome presented to it. Doudna is the lead author of the Science article
calling for control of the technique and organized the meeting at which
the statement was developed.
Though highly efficient, the technique occasionally cuts the genome
at unintended sites. The issue of how much mistargeting could be
tolerated in a clinical setting is one that Doudna’s group wants to see
thoroughly explored before any human genome is edited.
Scientists also say that replacing a defective gene with a normal one may seem entirely harmless but perhaps would not be.
“We worry about people making changes without the knowledge of what
those changes mean in terms of the overall genome,” Baltimore said. “I
personally think we are just not smart enough — and won’t be for a very
long time — to feel comfortable about the consequences of changing
heredity, even in a single individual.”
Many ethicists have accepted the idea of gene therapy, changes that
die with the patient, but draw a clear line at altering the germline,
since these will extend to future generations. The British Parliament in
February approved the transfer of mitochondria, small DNA-containing
organelles, to human eggs whose own mitochondria are defective. But that
technique is less far-reaching because no genes are edited.
There are two broad schools of thought on modifying the human
germline, said R. Alta Charo, a bioethicist at the University of
Wisconsin and a member of the Doudna group. One is pragmatic and seeks
to balance benefit and risk. The other “sets up inherent limits on how
much humankind should alter nature,” she said.
Some Christian doctrines
oppose the idea of playing God, whereas in Judaism and Islam there is
the notion “that humankind is supposed to improve the world.” She
described herself as more of a pragmatist, saying, “I would try to
regulate such things rather than shut a new technology down at its
beginning.”
Other scientists agree with the Doudna group’s message.
“It is very clear that people will try to do gene editing in humans,”
said Rudolf Jaenisch, a stem cell biologist at the Whitehead Institute
in Cambridge, Massachusetts, who was not a member of the Doudna group.
“This paper calls for a moratorium on any clinical application, which I
believe is the right thing to do.”
Writing in Nature last week, Edward Lanphier and other scientists
involved in developing the rival zinc finger technique for genome
editing also called for a moratorium on human germline modification,
saying that use of current technologies would be “dangerous and
ethically unacceptable.”
The International Society for Stem Cell Research said Thursday that it supported the proposed moratorium.
The Doudna group calls for public discussion but is also working to
develop some more formal process, such as an international meeting
convened by the National Academy of Sciences, to establish guidelines
for human use of the genome-editing technique.
“We need some principled agreement that we want to enhance humans in
this way or we don’t,” Jaenisch said. “You have to have this discussion
because people are gearing up to do this.”
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Biologists fear DNA editing procedure can alter human DNA
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