After a Chinese scientist announced this week the birth of twin girls whose DNA he had altered many months earlier when they were microscopic, single-cell embryos, condemnation of this previously secret experiment was swift and absolute. Scientists and ethicists from around the world called it “premature” and “irresponsible.”

The majority of this criticism is motivated by major concerns about safety — we simply do not yet know enough about the impact of CRISPR-Cas9, the powerful new gene-editing tool, to use it create children. But there’s a second, equally pressing concern mixed into many of these condemnations: that gene-editing human eggs, sperm, or embryos is morally wrong.

That moral claim may prove more difficult to resolve than the safety questions, because altering the genomes of future persons — especially in ways that can be passed on generation after generation — goes against international declarations and conventions, national laws, and the ethics codes of many scientific organizations. It also just feels wrong to many people, akin to playing God.

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As a bioethicist and a lawyer, I am in no position to say whether CRISPR will at some point prove safe and effective enough to justify its use in human reproductive cells or embryos. But I am willing to predict that blanket prohibitions on permanent changes to the human genome will not stand. When those prohibitions fall — as today’s announcement from the Second International Summit on Human Genome Editing suggests they will — what ethical guideposts or moral norms should replace them?

Few would argue that we should not try to prevent the transmission of genes associated with life-shortening or otherwise extremely serious genetic diseases like Huntington’s disease, Tay-Sachs disease, or even some breast and ovarian cancers. Indeed, doing so is already an accepted practice in medicine.

As genome-sequencing pioneer Eric Lander and others have said, instead of using gene editing, parents with or at high risk of genetic diseases can use in vitro fertilization combined with preimplantation genetic testing to identify embryos unaffected by one or more particular conditions. Or they can undergo prenatal testing to determine if a particular fetus carries a potentially devastating gene.

For some people, though, discarding embryos and terminating pregnancies are morally unacceptable acts. If an embryo’s DNA could be edited instead, families with moral or religious misgivings could transfer all their embryos, as could prospective parents who, like many IVF patients, have few embryos to begin with. More importantly, prospective parents worried about more than one genetic marker, and who therefore might not have any “unaffected” embryos, could use gene editing to make changes at multiple places in their embryos’ genomes.

If that scenario sounds like something out of the science fiction movie GATTACA, that’s because it is. Yet that’s the very prospect that the emergence and refinement of CRISPR and other gene-editing tools, and this week’s news, seem to place just within reach. In GATTACA, the parents of a young boy they conceived naturally visit a genetics clinic to select the genetic make-up of their second child. When their doctor lists the many changes he has made to their embryos — from eliminating genes associated with myopia and alcoholism to those for premature baldness, as well as selecting eye, hair, and skin color — the couple balks, asking “if it’s good to leave a few things to chance?” Their doctor reassures them that they are just giving their child “the best possible start” by relieving him of “additional burdens.”

The difficult moral question that this ever-less-remote technology raises, then, is not whether it is ever morally acceptable to eliminate, edit, or repair the genes of future persons. It will be very difficult to cogently argue that such an action is wrong in principle.

Instead, the question must become how far to take the very laudable impulse to offer children the best possible chances in life. This is a question for international bodies, like the United Nations, as well as the leaders at this week’s Second International Summit on Human Genome Editing in Hong Kong, and for national governments, many of which have laws prohibiting any and all germline modification in humans.

But it is also a question for ordinary people, both because we elect those who will be asked to change such laws and because we — especially anyone who is today a teenager or a child — will be the prospective users of this technology. In a country such as the U.S., which has up until now been very hands-off when it comes to most uses of assisted-reproduction technologies, there’s a very real chance that decisions about whether to use gene-editing in embryos, and in what ways, will eventually be left up to individuals. That means that my daughter, who is now 9 years old, may well be offered gene editing services for her embryos 20 or 30 years from now (most likely for a considerable fee). How will she decide what to do—and if she does use the technology, how far to go with it?

Some ethicists and the CEOs of some genetics companies are enthusiastic about parents using genetic technologies not simply to prevent serious disease but to have “the best children.” They look forward to a future in which gene editing of eggs, sperm, or embryos for a variety of diseases and traits is on offer. When the technology comes to market, I expect them to argue that using it to alter all sorts of genes is a responsibility of parenting —that gene editing is what good parents do.

My hope is that by the time such services arrive, people around the world will have developed a more sober attitude towards genetic technology than the almost blind optimism that today drives people to give their DNA to companies who promise to tell them who they really are, and will agree that the impulse to control their descendants’ genes, like the impulse to choose their descendants’ professions or passions or spouses, should generally be held in check.

Cultivating an attitude of acceptance and wonder when it comes to their child’s or grandchild’s DNA does not oblige future parents to do nothing about lethal or life-limiting genetic diseases. Indeed, I think that blanket prohibitions on germline modification must be scrapped. But this cautious attitude towards gene editing does counsel restraint and deliberation, suggesting we use germline gene editing sparingly.

We must remain skeptical of the notion that it makes sense to speak of having the best child or of maximizing a future person’s genes, and be on guard against the notion that doing so is a necessary element of good parenting. Humans have known for centuries, if not millennia, that children are a gift, and the civil rights and disability rights movements have shown us the diverse ways in which people with highly varied genomes can flourish. As we enter an age of gene editing, these are the norms and values that must guide us.

Josephine Johnston is director of research and a research scholar at The Hastings Center, a bioethics research institute in Garrison, N.Y., where she works on ethical, legal, and policy issues in genetics and reproductive medicine.

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  • Once lawyers, bioethicists etc attempt to take centre stage in this debate, they need to be reminded of another one, the recombinant DNA debate of the 1970s and the extravagant claims that were made then. Imagine the world where recombinant DNA was permanently nipped in the bud by a worldwide ban in the 1970s. No human genome sequence, no GMO and no CRISPR.

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