A group of geneticists has called for a moratorium on research into modifying heritable human DNA — a practice that could lead to so-called "designer babies." But as scientists consider this drastic proposal, they should also recognize the potential benefits this technology could afford – and the risks of an outright ban.

Before we begin, you should be familiar with the two broad types of gene therapy. So-called "somatic" gene therapies target the non-reproductive cells of the body, and affect only the patient receiving the therapy. In other words, the genes addressed by somatic gene therapies are not heritable.

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Germline gene therapies, in contrast, are genome-editing techniques that affect egg and sperm cells. The modification of these germ cells can result in all the cells in the organism containing the modified genetic information, which would allow the altered code to be passed down to subsequent generations.

In an editorial published earlier this month at Nature, geneticist Edward Lanphier and four other researchers currently investigating somatic gene therapies call for a temporary ban on germline gene therapy, citing "grave concerns regarding the ethical and safety implications of [research into germline gene therapies]." The authors also express fear that such research could have a "negative impact... on important work involving the use of genome-editing techniques in somatic (non-reproductive) cells" – i.e. their own research.

In their Nature letter, Lanphier and his colleagues write:

In our view, genome editing in human embryos using current technologies could have unpredictable effects on future generations. This makes it dangerous and ethically unacceptable. Such research could be exploited for non-therapeutic modifications. We are concerned that a public outcry about such an ethical breach could hinder a promising area of therapeutic development, namely making genetic changes that cannot be inherited.

At this early stage, scientists should agree not to modify the DNA of human reproductive cells. Should a truly compelling case ever arise for the therapeutic benefit of germ­line modification, we encourage an open discussion around the appropriate course of action.

Today, 15 of 22 European nations prohibit the modification of human germ lines. It's also illegal in Canada. In the U.S., legislators haven't officially prohibited this sort of research. That said, the NIH's Recombinant DNA Advisory Committee has stated that it "will not at present entertain proposals for germ line alterations."

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Lanphier and his colleagues would like to take the NIH's injunction a step further by introducing a voluntary moratorium, which would serve to discourage human germline modification and raise public awareness about the issue.

Therapy vs. Enhancement

The researchers published this article because, in their words, "It is thought that studies involving the use of genome-editing tools to modify the DNA of human embryos will be published shortly."

Lamphier and his colleagues claim that they, like others, "oppose germline modification on the grounds that permitting even unambiguously therapeutic interventions could start us down a path towards non-therapeutic genetic enhancement." But this stance is not particularly helpful, given that the line distinguishing therapy from enhancement is not so clearly drawn.

Human health, after all, is a normative concept. It's driven by advances in the medical sciences and changes to social conceptions. Consequently, as time passes, it will be increasingly difficult to distinguish between a therapeutic intervention and an enhancement.

For example, vaccinations are an enhancement — a super-immunity we're not born with. Having the capacity to read, acquiring a a good education, and being able to access the Web can be considered an enhancement. In future, we can expect to be further "enhanced" by synthetic organs, artificial limbs, nootropics (think about how Ritalin has already been used by people who don't have ADD), and nanotechnology. Our species is on the cusp of the enhancement era, so we'd better start getting used to it.

A Reproductive Right?

Human trait selection can also be considered a form of assisted reproduction, one not unlike in vitro fertilization. Consequently, it can be seen by prospective parents as an indelible component of reproductive liberty and the right to bear children according to their desires and values — so long, of course, as these genetic modifications are safe, effective, and governed by institutional processes.

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Fears of parents wanting to alter their offspring's eye or hair color misses the point, as are concerns that parents will demand a "perfect child." The nature of the proposed enhancements, as it were, have a bit more substance to them than that.

For example, scientists have already isolated the genetic variants for extra-strong bones, lean muscles, insensitivity to pain, and virus resistance. All those seem quite reasonable, as do those modifications that boost immunity to age-related disorders (again, in a certain light, even anti-aging can be seen as a kind of enhancement). In future, parents may also be able to bear offspring with a diminished proclivity for psychological disorders, including depression.

And as noted by Duke University bioethicist Allen Buchanan and his co-authors in From Chance to Choice: Genetics and Justice, the prospect of genetically modifying our offspring will also have a profound influence on our appreciation of distributive justice (i.e. making sure most people have access), equality of opportunity, the rights and obligations of parents (e.g. could un-modified children sue their parents for failing to use these technologies?), the nature and meaning of disability, and the very concept of human nature, and what it even means to be human.

Not Eugenics

Some might argue that genetically modifying human offspring sounds like a transhumanist or even eugenicist agenda — but as Harvard geneticist George Church has noted, "throwing in the word 'transhumanists' is unnecessarily confusing." When asked if germline modifications represent the next logical step in human genetics research, he told the Knoepfler Lab Stem Cell Blog:

I don't think that germline is the next goal (nor next logical step), but it might be an acceptable side-effect of treating genetic diseases early, safely and effectively. Many gene therapies currently in clinical trials are already aimed at young children to avoid permanent damage. Treating sperm and eggs could reduce the number of abortions (spontaneous and induced) and the number embryos needed in IVF clinics.

In other words, there are unforeseen and peripheral benefits to this research; when a ban is placed on research, the biggest loss is liable to be a therapeutic discovery we could never have predicted or account for from our current vantage point. Another problem of a research ban is the likelihood that black markets will emerge. In my opinion, it's far better to have a regulated and monitored development regime than a slew of shady basement labs.

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And in regards to the claim that germline therapy could constitute a new form of eugenics, Church had this to say:

Eugenics in USA from 1907 to 1981 involved government sterilization of 65,000 individuals to "improve" the gene pool. The new technology enables parents to make choices about their children just as they might with Ritalin or cleft palate surgery to "improve" behavior or appearance. To prevent such parental decisions, the government would again interfere with reproductive choice, but this time in the apparent opposite direction in terms of improving the gene pool. To give the same name (eugenics) to these two scenarios seems unnecessarily confusing. Should we be talking about benefits and risks? Yes. Frequently and engaging many voices.

Many years ago at a bioethics conference at Yale, I referred to state-imposed restrictions on the human germ line as "neugenics" — a top-down injunction to ensure human genetic stasis. It would appear that Dr. Church shares my concern.

Moving Forward

The authors of the Nature editorial are not wrong to call attention to this issue. As geneticists, they know what's at stake. But to call for an outright moratorium is clearly not the way to go. Let's have an open discussion, absolutely – but let's be sure to recognize that humanity is a species in transition; heritable germline modifications may very well be the way of the future. Rather than being forged by the powers of natural selection, humanity is finally taking its destiny — and its genomes — into its own hands.

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For further reading on this subject I highly recommend John A. Robertson's Children of Choice: Freedom and the New Reproductive Technologies, Allen Buchanan's Better Than Human: The Promise and Perils of Enhancing Ourselves, Gregory Stock's Redesigning Humans: Choosing our Genes, Changing our Future, and Ramez Naam's More Than Human.

Image: Nevodka/Shutterstock