Editing Human Beings

Editors Note: An abridged version of this article was published on Desiring God on July 21st, 2015.

Early in 2015, a group of Chinese scientists announced a world first; they had genetically modified human embryos. The announcement was met with skepticism and widespread disapproval. Nature and Science, two leading publications rejected the study.[1] Scientists and bioethicists across the political spectrum claimed that this type of genetic modification crossed an impermissible ethical line.

We agree, and we unflinchingly reject this line of research. But, before we arrive at this conclusion, we recognize the church needs to become aware of this latest scientific development in genetic research, why it was attempted, the fallout and its consequences, and what specific ethical lines it crosses for us as Christians. Please allow us a moment to explain.

The Gene-Editing Technique

In an effort to correct the gene for beta-thalassaemia, an often fatal blood disorder, the scientists experimented upon 86 human embryos retrieved from fertility clinics. They specifically selected what they claimed were nonviable embryos; the embryos had three pro-nuclei, meaning they had been fertilized with two sperm. This kind of embryo cannot continue development through live birth.

The technique the scientists used is known as CRISPR/Cas9 (CRISPR is the acronym for ‘clustered regularly interspaced short palindromic repeats,’ a genetic marker in DNA). It has potential for correcting genetic errors in mature cells, which would not affect the patient’s reproductive DNA (carried in the eggs or sperm, often referred to as germline cells), which then would be passed on to any future children. CRISPR/Cas9 demonstrates potential for beneficial genetic interventions and has been used to modify bone marrow cells in order to increase resistance to HIV.    

Cas9 is a CRISPR-associated protein or enzyme complex that that is targeted to specific sections of DNA by a CRISPR guide RNA; Cas9 cuts the DNA double strand, and deletes the defective portion or adds a corrective portion—a sort of molecular scissors. It is somewhat analogous to the “find and replace” feature in Word documents. Imagine that throughout the document, you typed the word ‘tehology.’ The CRISPR guide tool identifies the genetic equivalent of only the misspelled words, targeting the Cas9 tool to remove and correct the reversed letters—‘e’ and ‘h’—to produce ‘theology.’ It would not reverse the ‘e’ and ‘h’ in, say, ‘behave’ or ‘behold.’ Nor would it introduce spelling errors anywhere else in the document.                     

Ethical Concerns:

Safety and Unforeseeable Consequences

When the CRISPR/Cas9 technique was originally announced, it was hailed as extraordinarily precise,[2] able to locate and correct even a single base pair (two nucleotides that are linked on the DNA double helix “ladder”). This accuracy in locating the abnormal DNA (genes) and precision in correction would resolve one of the longstanding safety concerns so frequently raised about genetic technologies: unintentionally changing gene segments. Furthermore, the technique was hailed as making gene editing relatively simple and dramatically reducing costs associated with the technology.[3] Early research utilizing the CRISPR/Cas9 technique in animal models and adult human cells demonstrated clear promise. The harsh reality of translating these techniques to human embryos is quite different.

Of the 86 embryos the Chinese scientists reportedly used, 71 survived for two days. Of the 54 that were tested, 28 showed a genetic change, or had been “edited.” The unhealthy gene, or misspelled segment, was successfully removed. A corrected or healthy segment was spliced into only a few. Additionally, the CRISPR/Cas9 complex did not confine itself to the targeted abnormal gene, but changed normal parts of the DNA (essentially introducing misspellings). This “off target” effect is worrisome, as it causes unforeseeable mutations.

Mosaicism also occurred in some of the embryos, an additional safety concern. Mosaicism means that unlike the accurate “Find and Replace” analogy above, only a fraction of the embryos’ cells with targeted DNA sequences were changed, rather than all of the cells. As the researchers themselves suggest, it would be “impossible to predict gene editing outcomes by preimplantation genetic diagnosis” (PGD) to confirm whether the intervention had been successful. Depending upon which cell is extracted for PGD, the embryo could appear either ‘edited’ or ‘unedited.’

Further, there is no way to predict the interaction with other genes in the cell. Indeed, the entire scope of unintended changes to the whole genome was unknown due to the type of DNA scanning technology that the Chinese team used—whole exome sequencing, which only investigates a few segments, versus the more detailed whole genome sequencing. There could be additional unintended mutations that show up in other gene segments. Or, there could be effects that only appear in a future generation, as has already happened when daughters of women who took DES during pregnancy later contracted cervical cancer.

The experiment was a failure. In short, none of the embryos met two basic criteria: “precisely altered genes in every cell with no accompanying DNA damage.”[4]

Germline Manipulation

The stated goal of gene editing in human embryos is noble: eradication of serious inheritable diseases. Up until now, gene research involved adult cells (also called somatic cells), seeking a cure for only a particular patient, who would be protected by normal safeguards such as informed consent. Gene editing of reproductive DNA is infinitely more powerful, irreversibly changing future generations.   

In the wake of the announcements by the Chinese researchers, Francis Collins, Director of the National Institutes of Health, stated unequivocally that germline manipulation “has been viewed almost universally as a line that should not be crossed.[5] This includes researchers and ethicists who approve of other research that destroys human embryos. Some have called for at least a moratorium, even as at least four groups of Chinese researchers seem to be plowing ahead.[6]

Beyond concerns of safety for the human gene pool and the potential for grave and long-term harm to the children born with such alterations, the international community has been almost universally opposed to germline interventions that permanently alter human DNA. However, we question how long the line of opposition will hold. If scientists succeed in improving success rates, the lure of eradicating life-threatening and disabling diseases may prove too hard to resist. Recent approval of mitochondrial donation in the UK, which many understand to be a form of germline intervention, points to the challenges of governments and researchers to resist evolving technologies no matter how much they may be initially controversial. Many see the history of the public debate over embryonic stem cell as it quickly moved from wide-spread resistance until all other possibilities had been exhausted, to cautionary acceptance, to open endorsement as a case in point.

Lack of Informed Consent     

Some gene therapies can be conducted ethically. Somatic cell interventions for the therapeutic benefit of a particular patient require the patient to properly consent to the risks involved with the procedure. By way of contrast, future generations are unable to consent to a pre-emptive alteration of their DNA via germline intervention. Of course, parents often make important medical decisions on behalf of their children, but this is a permanent decision, and one that at this point is completely experimental. Such interventions, even if still speculative, raise important questions on the nature of procreation and the appropriateness of technological intervention in the formation or production of children.

Thinking about this as Christians

Children Are a Gift

Gene editing also raises a variety of considerations from a Christian perspective. This type of direct intervention could distort our traditional understanding of children as gift to a model where children are treated as products of choice and intention. That is, germline manipulation seems to regard the child as a product than can be improved upon, rather than a gift from God. It encourages the rejection of embryos that are not successfully edited, which stands in marked contrast to a Christian posture of unconditional welcome and hospitality. While the interventions under consideration are intended to eliminate serious diseases, concerns of, and the temptation to produce, designer babies are not far away.

Gene Editing Can Become Eugenics

A Christian perspective of humans as complex physical and spiritual beings stands in conflict with contemporary trends that reduce the nature of human beings solely to genetic information. Tendencies toward genetic reductionism have been coupled with a soft revival of eugenic attitudes. The eugenics of previous eras declared some to be superior, often at the expense of others’ lives. The new eugenics passively uses prenatal genetic tests to eliminate genetic diseases through abortion. Rates of abortion for those parents who receive an adverse diagnosis for the child with a genetic abnormality such as Trisomy 21 (Down syndrome), are distressingly high.

With an increasing awareness of how our DNA contributes to who we are as physical beings, there is an increasing danger to reduce persons to their genetics. Particularly in the context of genetic abnormality and disability what is often lost in these dilemmas is the humanity of the disabled; their personhood; the reality that they also are bearers of the image of God. Some wonder how people with congenital disabilities will be welcomed in societies that actively seek to eliminate genetic diseases through germline interventions or by preventing the birth of any children who might carry a “defective” gene.

Final Considerations

One aspect that should be of concern to Christians and the broader culture is the matter of justice: will these therapies be so costly that they exclude the disadvantaged, and may even exacerbate already existing domestic and global socio-economic inequalities? Questions of allocation and access are common to many types of emerging technologies, and are a special concern for those that offer potential not only for therapeutic use, but also for the possibility of human enhancement or alteration of the human species as such.

Also, given the high rate of embryos destroyed in these experiments (100%), what would we do with any knowledge that is gained from this and future research? This raises significant questions about participating or complicity with immoral acts. The alleviation of suffering is a good and appropriate goal for medicine and biotechnology research. However, they are not ultimate goods, and cannot redeem immoral actions to achieve them. For those considering this as an experimental therapeutic intervention, serious questions are raised with respect to the current maturity of this technology, and thus the likelihood for serious harm outweighs any potential benefit.

Finally, with respect to questions of complicity and significant sacrifice of embryonic human life in the pursuit of highly experimental research, this approach knowingly sacrifices the lives of some to potentially improve someone else’s life. For these reasons, we join the chorus of voices condemning the actions of these researchers. At the very least, we affirm their call for transparent public discussions surrounding the role of genetic interventions and a moratorium on germline interventions. As Christians, we should unflinchingly reject this line of research. The moral cost cannot be justified, no matter how noble the goal.



[1] David Cyranoski, “Chinese Scientists Genetically Modify Human Embryos,” Scientific American, April 22, 2015. http://www.scientificamerican.com/article/chinese-scientists-genetically-modify-human-embryos/

[2] Steve Connor, “Exclusive: ‘Jaw-dropping’ Breakthrough Hailed as Landmark in Fight Against Hereditary Diseases as Crispr Technique Heralds Genetic Revolution.” The Independent, November 7, 2014. http://www.independent.co.uk/news/science/exclusive-jawdropping-breakthrough-hailed-as-landmark-in-fight-against-hereditary-diseases-as-crispr-technique-heralds-genetic-revolution-8925295.html

[3] Connor, “Exclusive.”

[4] Ruth Macklin, “Altering Genetic Material: A Line that Must Not Be Crossed,” The Doctor’s Table blog, Albert Einstein College of Medicine of Yeshiva University, April 30, 2015. http://blogs.einstein.yu.edu/altering-genetic-material-a-line-that-must-not-be-crossed/

[5] Francis Collins, “Statement on NIH Funding of Research Using Gene-Editing Technologies in Human Embryos.” National Institutes of Health, April 29, 2015. http://www.nih.gov/about/director/04292015_statement_gene_editing_technologies.htm

[6] David Cyranoski and Sara Reardon, “Chinese Scientists Genetically Modify Human Embryos,” Nature, April 22, 2015. http://www.nature.com/news/chinese-scientists-genetically-modify-human-embryos-1.17378


Michael J. Sleasman, PhD, is the managing director and research scholar at The Center for Bioethics & Human Dignity at Trinity International University and an affiliate professor of bioethics at Trinity Graduate School. Michael is co-editor of and contributor to Everyday Theology: How to Read Cultural Texts and Interpret Trends (Baker Academic: 2007). His research explores the intersection of theology, emerging technologies, and ethics. 

Paige Cunningham, JD, is the Executive Director of The Center for Bioethics & Human Dignity. A graduate of Northwestern University Law School, she teaches, writes, and lectures on bioethics, public policy, reproductive ethics, and global women’s health. She contributed a chapter to Why the Church Needs Bioethics (Zondervan: 2011).

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