The Seduction of Designer Babies: Are Proponents of Germline Editing Telling the Whole Truth?
This past November, Chinese scientist He Jiankui announced the birth of twin girls whom he genetically edited as embryos — a revelation that, for several reasons, was met with near universal condemnation.
First, it’s widely agreed that the gene-editing tool used by Jiankui, CRISPR-Cas9 (CRISPR), is not yet safe enough for use in humans. Regardless, Jiankui employed CRISPR to remove the CCR5 gene from human embryos in an attempt to render them resistant to HIV. [Note: individuals who lack this gene have demonstrated resistance to HIV]. This particular application of CRISPR, known germline editing (i.e. the alteration of embryonic genomes), is especially risky given the heritably of the resulting edits. As such, prior to Jiankui’s experiment, CRISPR had never before been used to alter human embryos intended for implantation.
Jiankui, however, reportedly failed to inform the prospective parents recruited to his trial that a novel, genetic intervention was involved. Instead, Jiankui misleadingly told participants that he was testing an “HIV vaccine” in an apparent attempt to obfuscate the true risks associated with the research.
Furthermore, the now father of the edited twin girls purportedly entered the trial because he feared transmitting his HIV-positive status to his children. Paternal transmission of HIV, however, is extremely rare. Regardless, even the slim chance of transmission in this case could have been eliminated with a safe, low-tech intervention known as sperm washing. Consequently, the unique benefits of this particular application of germline editing quite clearly did not outweigh the known and unknown risks associated with the technology.
In fact, when Jiankui presented his research — which he kept largely under wraps until the twins were born — audience members were reportedly appalled by what they saw. It was clear from Jiankui’s own results that the embryos he ultimately brought to term were mosaics. In other words, the CCR5 gene was successfully removed only from some of the embryos’ cells — a result thought to both limit the effectiveness of the intervention and pose significant risks to the twins’ health.
However, despite the united front against Jiankiu’s particular application of germline editing, the long-standing, general consensus against manipulation of the human germline is swiftly eroding. For example, the National Academies of Sciences in the US and the Nuffield Council on Bioethics in the UK — non-profit entities that influence policy-making in their respective countries — have released reports condoning germline editing under certain circumstances. Indeed, the majority of contributors to the CRISPR debates argue that germline editing should at least be developed and permitted for the removal of genes that underlie certain monogenetic conditions (e.g., cystic fibrosis, Tay Sachs, Huntington’s disease).
These conditions are somewhat unique in that they are inextricably linked to a single gene. In other words, possession of one copy of such a gene in the case of a dominant condition (e.g., Huntington’s disease) or two copies in the case of a recessive condition (e.g., Tay Sachs) signals a certainty that the related disease will manifest.* This one-to-one ratio between genetics and disease development is relatively rare given that most conditions emanate from a complex interplay of multiple genetic and environmental factors. It’s also relevant to note that monogenetic conditions are uniquely debilitating and often lack effective treatments.
Proponents thus argue that once we master the underlying technology, it will be ethical to target these conditions with germline editing because: 1) such an application does not implicate any of the concerns related to “designer babies”; 2) our clear understanding of the relationship between these conditions and the underlying genes limits the risk of unintended consequences; and 3) the pain and suffering associated with these conditions, for which there are otherwise no viable therapies, will be prevented.
In response to these assertions, it’s first important to note that germline editing cannot be legitimately characterized as a therapy or treatment. A therapy alleviates the pain and suffering of an individual afflicted by a given condition. For example, removal of the cystic fibrosis gene from the lung cells of patients suffering from the condition (i.e., somatic cell editing) would constitute a therapy. However, the use of CRISPR to edit the cystic fibrosis gene from embryos created in vitro in order to bring into being a person who might not have otherwise existed constitutes a reproductive technology.
This distinction is significant given that other reproductive technologies exist to prevent the transmission of monogenetic conditions in the vast majority of instances — a fact conspicuously ignored by many proponents of germline editing. For example, a technology known as Preimplantation Genetic Diagnosis (PGD) (i.e., the genetic testing of embryos created in vitro) can help couples affected by genetic disease have healthy, genetically related children. Given the relative rarity of the genes underlying most monogenetic conditions, most affected couples can produce some amount of healthy embryos. Such couples can therefore use PGD in conjunction with IVF to test for and selectively implant embryos that will not develop the genetic disease at issue.
However, in the extraordinarily rare instance that one prospective parent carries two copies of a gene related to a dominant, monogenetic condition (e.g., Huntington’s disease), all of the couple’s embryos will carry the gene and therefore develop the disease. Such a couple, however, could still use a donor gamete (i.e., sperm or egg) to achieve a healthy child that is genetically related to one parent.
It’s only in the exceedingly unlikely event that both prospective parents carry two copies of a gene for the same genetic condition that the unique value of germline editing obtains. Such a couple could not have a healthy, genetically related child by existing means
Supporters of germline editing, therefore, hold up such a case as the posterchild for advancing the technology. They also use the fact that the technology is so rarely necessary to dismiss concerns that germline editing will have a significant impact on society and human evolution. There are, however, a few problems to note with these arguments.
First, it’s important to remember that the extraordinarily limited number of individuals who would be uniquely helped by germline editing could still become parents via adoption. Thus, to pursue germline editing to enable such a small group of people to have genetically related children begs the question of just how essential genetically related children are. It’s certainly apparent that many people highly value having genetically related children. However, whether this preference should be vindicated by science and law despite long-standing arguments against alterations of the human germline is another question. Instead, in a world where there are many unwanted children and environmental concerns that militate against increasing the population, perhaps the desire for genetically related children should be tempered rather than catered to.
Regardless, it’s important to note that both prospective parents in a couple who could not otherwise produce healthy, genetically related embryos, will likely suffer from the deadly genetic condition at issue. The child ultimately brought into existence through germline editing would therefore likely lose one or both parents at a young age — an ethically troubling outcome for obvious reasons.
Finally, while proponents use the limited need for such a technology to dismiss the related ethical concerns, one might ask: why invest so many valuable resources — resources that could ostensibly be put towards developing cures for the relevant genetic conditions — to develop a reproductive technology needed by so few? Perhaps, these limited cases, which are notably sympathetic, are not in fact the end game but rather trojan horses for other applications of germline editing. Indeed, drug policy reformers have used a similar tactic to legalize cannabis, i.e., legalize cannabis for a limited set of medical applications and then push for full legalization once the public is inured to the substance’s presence within society.
In the case of germline editing, if the technology is approved to prevent the inheritance of monogenetic conditions, proponents could eventually push to employ the technology to eliminate genes related to conditions caused by multiple genetic and environmental factors. In fact, the National Academy of Sciences’ report indicates that it might one day be acceptable to edit BRCA genes from human embryos. However, unlike the cystic fibrosis and Huntington’s disease genes, which signal a certainty that the related conditions will manifest, an individual with a BRCA1 gene may never develop breast cancer. Consequently, such an application of germline editing seems to offer something more akin to enhancement by eliminating even the predisposition to disease.
Furthermore, such uses of germline editing are arguably much riskier given our relatively crude understanding of the multiple genetic and environmental factors at play. For example, it’s unclear what effect eliminating the BRCA1 gene will have on the expression of other, related genes and therefore overall health. Such additional risks are arguably difficult to justify given that, unlike Huntington’s Disease or cystic fibrosis, breast cancer is now a relatively treatable condition.
Regardless, it’s further possible that at least some proponents of the technology, despite public assertions to contrary, are seduced by the prospect of “designer babies”. Indeed, such a desire to design offspring is already apparent in our society. For example, there are currently countless IVF clinics in the US that offer PGD for the selection for non-disease related traits such as eye and skin color. Relatedly, studies indicate that elimination of the CCR5 gene can improve cognition. A recent article thus posits that Jainkiu might have had ulterior motives for selecting the CCR5 gene for removal. Perhaps he was not so much concerned with protecting the twins against an unlikely HIV infection as he was beguiled by the enhancement implications of his edits. In fact, in the same article, a researcher who explores the cognitive benefits of removing the CCR5 gene from mice notes that, due to his research, he “sometimes interacts with figures in Silicon Valley and elsewhere who have…an unhealthy interest in designer babies with better brains.” It’s thus not difficult to imagine that even if germline editing is initially approved only for a limited set of “therapeutic” circumstances, proponents may push the technology towards uses that implicate all the safety and ethical concerns related to ‘designer babies’.
To conclude, it seems that many proponents of germline editing have yet to be completely forthcoming with their reasons for supporting the technology. However, given the significant implications to individuals, society, and the species associated with taking unprecedented control over human evolution, it’s essential that the debates surrounding germline editing are fully transparent. Only then will the public, vis-à-vis governments, be able to successfully guide the development of the technology in a responsible way.
*As a refresher, each of us inherits two sets of genes: one inherited our mother and one from our father.
The Seduction of Designer Babies: Are Proponents of Germline Editing Telling the Whole Truth?
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