Editing Of Human Embryo Genes Raises Ethics Questions
Biotechnology: Scientists and lawmakers are anxious about altered genomesA little more than a decade after scientists first unraveled the human genome, some researchers are trying to rewrite it. Advances in gene-editing technology have provided relatively inexpensive and easy ways to delete, insert, or replace genes in human cells to correct defects associated with devastating diseases such as cystic fibrosis and sickle cell anemia. Gene-editing tools could also be used to alter plant and animal genomes to boost agricultural yields and food production or to modify insect genomes to reduce the spread of diseases such as malaria.
Not only are gene-editing tools scientifically promising, they also
have the potential to be highly lucrative commercially. But with that
promise comes worries that gene-editing technology could be used to
create designer babies with enhanced traits, such as higher intelligence
or greater beauty. Many scientists are also worried that the technology
could change the human germ line—the DNA in reproductive cells that is
passed on from one generation to the next—in unexpected or dangerous
ways.
The ethical implications and risks of human gene editing came to a
head in April. That’s when a group of Chinese scientists reported that
they had attempted to alter a gene associated with a potentially fatal
blood disorder in the cells of nonviable human embryos (Protein & Cell 2015, DOI: 10.1007/s13238-015-0153-5).
The experiment was largely unsuccessful. Most of the embryos died, or
the gene targeted in the experiment was not altered. Even in a few
embryos where the gene was successfully modified, researchers observed
other DNA damage in their cells. Some researchers are worried, however,
that this work is just the tip of the iceberg and more studies like it
will soon follow. Earlier this year, before the Chinese scientists
published their work, a group of leading scientists, bioethicists, and
law experts met in California to map out a plan toward ensuring that
gene-editing technology is not used in a dangerous or unethical way.
In a commentary published in March in Science (2015, DOI: 10.1126/science.aab1028),
the group calls for a moratorium on the use of gene-editing
technologies for clinical applications. The group stops short, however,
of saying that research involving editing genes in human embryos, eggs,
or sperm cells should cease.
Instead, they argue that the research on nonviable human embryos
should continue, as long as it does not result in pregnancies. The
authors include Jennifer Doudna,
a biochemist at the University of California, Berkeley, whose work on
the immune systems of bacteria helped lead to the development of a
widely used gene-editing technology called clustered regularly
interspaced short palindromic repeats (CRISPR) that relies on the
engineered CRISPR-associated protein 9 (Cas9). Doudna is currently
fighting to get control of the intellectual property rights to
CRISPR-Cas9. Although many scientists give her credit for the invention,
the first patents for the technology were granted to Feng Zhang, a
scientist at the Broad Institute and Massachusetts Institute of
Technology. Both have started companies to commercialize the technology.
Doudna organized the California meeting when she began hearing
rumors that scientists were using CRISPR-Cas9 to change DNA in human
embryos. Chinese scientists had already used the technology to create
genetically altered monkeys.
Just one week before Doudna and 17 other scientists published their commentary in Science, a different group of scientists published a similar editorial in Nature (2015, DOI: 10.1038/519410a).
That group is seeking a moratorium on all gene editing of human embryos
or human reproductive cells, including research in this area.
“Genome editing in human embryos using current technologies could
have unpredictable effects on future generations,” the researchers,
including Edward Lanphier, president and chief executive officer of
California-based Sangamo BioSciences, wrote in the Nature
editorial. The team is developing new therapies for various diseases
using a proprietary platform that relies on zinc finger proteins—a rival
technology to CRISPR-Cas9.
Genetically engineering human germ-line cells is prohibited in many
European countries, but not in the U.S. or China. In the U.S., however,
federal research money cannot be used to fund such work.
“The concept of altering the human germ line in embryos for clinical
purposes has been debated over many years from many different
perspectives and has been viewed almost universally as a line that
should not be crossed,” Francis S. Collins, director of the National
Institutes of Health, said in response to the news
that scientists in China were using gene-editing technology to alter
human embryos. “NIH will not fund any use of gene-editing technologies
in human embryos,” he stated.
But research supported by private funding in the U.S. is not subject
to the same restrictions—and it has little oversight unless the work
attempts to establish a pregnancy. In that case, researchers would need
approval from the Food & Drug Administration.
The report from China caught the attention of congressional lawmakers and prompted a hearing earlier this month of the Science, Space & Technology Subcommittee on Research & Technology in the House of Representatives.
Calling the research “alarming,” Rep. Lamar Smith (R-Texas), chairman
of the House Science, Space & Technology Committee, said that “the
U.S. can and should provide scientific and moral leadership” in this
area.
Leading scientists assured lawmakers at the hearing that work is
under way to better understand the ethical implications and risks of
research involving gene-editing technology, particularly when applied to
human embryos.
Victor J. Dzau, president of the
National Academy of Medicine, highlighted an initiative launched last
month by the National Academy of Sciences and National Academy of
Medicine to examine the risks and benefits of gene-editing research,
including ethical considerations. As part of this effort, an
international meeting scheduled for this fall will examine ethical and
governance issues at the global level, Dzau said at the hearing. The
initiative will generate a formal report to guide scientists,
regulators, and clinicians, he added.
Jeffrey P. Kahn,
a bioethics professor at Johns Hopkins University, suggested to
lawmakers that scientific journals could serve as gatekeepers by not
accepting papers related to research on gene editing unless authors
provide details of an ethics review of the work.
The study by Chinese scientists that was published in Protein & Cell “was reportedly rejected by both Science and Nature
prior to its acceptance and eventual publication, with some reportage
indicating that ethics reviews played a role in the decision to reject
it,” Kahn testified. Neither Nature nor Science would comment on the matter to C&EN.
Although most ethics concerns related to gene editing have to do with
using the technology, some researchers have argued that “there may come
a time when we would consider it unethical not to do editing of the
germ line for certain kinds of applications,” such as treating dreadful
diseases, Doudna pointed out.
Gene-editing technology is widely available and being used in
research applications. It will be several years before it is used in
clinical applications in which cells are treated inside the body, Doudna
told the legislators. But applications in which cells are modified,
sequenced, and validated outside the body and then reintroduced into the
body are likely to be only one or two years away, she predicted.
In the meantime, there is still a lot to be learned about “human
genetics, gene-environment interactions, and pathways of disease,”
Doudna warned.
“Would it be appropriate to use the technology to change a
disease-causing genetic mutation to a sequence more typical among
healthy people?” she asked. “Even this seemingly straightforward
scenario raises serious concerns,” she said, “including the potential
for unintended consequences of heritable germ-line modifications.”
- Chemical & Engineering News
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