Politics & Policy

Experiments on Human Embryos Offer Little Hope for Curing Genetic Diseases

(Danil Chepko/Dreamstime)

As of this week, scientists in the United Kingdom can move ahead on genetically modifying human embryos. The U.K.’s independent Human Fertilisation and Embryology Authority granted scientists legal permission to alter the DNA of embryos in the first seven days after fertilization, although they are prohibited from implanting the altered embryos in women. In response to this groundbreaking step, Henry Miller wrote Tuesday on NRO that this is just a small step “toward the ultimate goal — eliminating terrible lethal genetic diseases from families through germ-line gene therapy.”

That would be a laudable goal. But it is worth noting that the actual experiments that the British scientists plan to conduct have little to do with gene therapy. The genes the scientists will be targeting are involved not in disease but rather in the growth and development of embryos and embryonic stem cells. Rather than repairing genes, the scientists will be disrupting genes in normal, healthy embryos so that they can learn about embryonic development. In any case, the United Kingdom prohibits genetic modifications that might be inherited, so once these embryos are genetically modified, the law mandates their destruction.

The sentiment that human embryos should be treated as expendable resources is not likely to change.

While these experiments might not be directed at any kind of actual therapy, perhaps they still represent, in some sense, a first step toward germ-line gene therapy to eradicate lethal genetic diseases such as sickle-cell anemia. But it’s not clear that the scientific community is very interested in pursuing germ-line therapy. As Miller notes, a recent international summit convened by scientists to discuss human-gene editing issued a moratorium on germ-line therapy. As the organizers of the summit wrote, “intensive basic and preclinical research is clearly needed,” including research aimed at “understanding the biology of human embryos,” but “if, in the process of research, early human embryos or germ-line cells undergo gene editing, the modified cells should not be used to establish a pregnancy.” That is to say, genetic experiments may be done on human embryos, but only if those embryos are not allowed to survive. This statement might not be authoritative, but the sentiment that human embryos should be treated as expendable resources is not likely to change.

Because unborn life is valued so cheaply by governments, the scientific community, and the in vitro fertilization (IVF) industry, germ-line gene therapy is unlikely to ever make much of a difference in how we deal with genetic disease. After all, in the vast majority of cases, scientists can already use another technique to selectively discard IVF embryos affected by genetic disease: pre-implantation genetic diagnosis (PGD), which is ethically fraught in its own way.

#share#Some critics of germ-line modification argue that PGD makes germ-line modification unnecessary, but curing genetic disease in embryos seems to be an ethical step up, not a step down, from killing embryos affected by genetic disease. Still, whether PGD or germ-line therapy or some other option is the morally right thing for parents to do, PGD is likely, practically speaking, to remain the major strategy for dealing with genetic disease. After all, the IVF industry in the United States already routinely discards enormous numbers of human embryos, so it is unlikely to adopt new, risky, unproven methods for editing disease-causing genes in embryos when they can simply selectively discard those embryos.

RELATED: The Case Against Human Gene Editing

For those rare cases where both parents are affected by a genetic disease in a way that guarantees that any child of theirs will have the disease — making PGD useless — the kinds of gene that have already been used to treat genetic diseases in adults and children will be available. Thus the need to move toward germ-line gene therapy on embryos is less urgent than Miller implies. Bone-marrow transplants for sickle-cell anemia, for instance, have already shown some promise, and these new gene-editing techniques could make such treatments even more effective. 

These early experiments on human embryos might be laying the groundwork for genetically designing human children.

Miller also alluded to other forms of germ-line engineering that do not involve the manipulation of human embryos; these might one day be useful in medical treatments. For example, as Miller notes, gene therapy in the sperm-producing cells of men affected by or carrying genetic disease might represent an ethical alternative to PGD for men concerned about the risk of genetic disease for their children. But it remains a highly speculative and impractical method for men, and it’s even more so for women. And like any of these high-tech methods for preventing genetic disease, it would be developed only if there were sufficient demand for a method of preventing genetic disease in children that does not involve the killing of early embryos.

The type of germ-line gene therapy that Miller discusses seems unlikely to come to pass, but this does not mean that no one will ever attempt to edit the genes of human embryos. In the future, parents might want genetic engineers to help them shape such traits as intelligence, height, and mood in their children. Parents who want smarter, taller, and more-docile children will find no help in existing genetic technologies, but gene-editing might one day provide them with control over such traits.

Miller is right that curing genetic disease is a noble goal. All who aim to protect human life, including embryonic human life, should support it. But these new gene-editing technologies hold little promise for actually curing genetic disease. Rather, these early experiments on human embryos might be laying the groundwork for genetically designing human children. And it’s not only the distant prospect of designer babies that should give us pause. More fundamentally, when we consider this week’s news about genetic experiments with human embryos, we should recoil at the cruel instrumentalization of unborn human life.

— Brendan Foht is assistant editor at The New Atlantis: A Journal of Technology and Society.

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