Genetic Scissors: Thoughts on Gene Editing

Jennifer A. Doudna and Emmanuelle Charpentier were recently awarded the Nobel Prize in Chemistry for their work on the gene-editing tool now known as CRISPR/Cas9.

This award has drawn the public’s attention to a technique that has been of interest (and concern) to bioethicists for several years — certainly since November 2018, when a Chinese scientist, He Jiankui, announced the birth of the world’s first gene-edited babies, a set of twins whose genomes were altered while they were embryos to render them immune to HIV infection. (In 2019, after a secret trial in Shenzhen, China, He was sentenced to three years in prison for violating medical regulations.)

If it is indeed the case that these babies had their genomes altered in the way that He claims (and some scientists have expressed doubts about this), their birth arguably marks the point at which considerations of the promises and dangers of the genetic revolution became practical rather than theoretical. As David Cyranowski, writing in Nature, puts it:

By engineering mutations into human embryos, which are then used to produce babies, He leapt capriciously into an era in which science could rewrite the gene pool of future generations by altering the human germ line. He also flouted established norms for safety and human protections along the way.

The genetic revolution – a revolution made possible by our ever-increasing knowledge of the human genome, along with the development of tools that will, or do, allow us to manipulate it – has the potential not only to change our material and social worlds (as the industrial and computer revolutions have already done), but also ourselves.

Scientist He Jiankui speaks during the International Summit on Human Genome Editing at the University of Hong Kong in Hong Kong, China 28 November 2018.

Scientist He Jiankui speaks during the International Summit on Human Genome Editing at the University of Hong Kong in Hong Kong, China 28 November 2018.

People tend to fall into two camps here as well, just as they do when thinking about MAID: optimists ask us to imagine a future in which we have vastly extended the human lifespan, radically reduced the number of diseases we are subject to and even enhance our physical and mental abilities. Pessimists, on the other hand, predict a future in which the human and natural worlds have been made markedly worse, because the changes the genetic revolution have made possible benefit only a few, already privileged groups, and the alterations made to human, animal and plant genomes end up producing undesirable and unfixable mutations. For the optimists, in short, the genetic revolution has the potential to create an almost unimaginably wonderful utopian future; for the pessimists, in contrast, the genetic revolution threatens us with all-too-imaginable dystopian futures like those penned by the best writers of science fiction.

Whether the optimists or the pessimists will be proven right remains to be seen. However, many ethicists – and bioethicists, in particular – see their role to be to warn people about the possible dangers of the genetic revolution, since the imagined benefits are touted by everyone from enthusiastic celebrities to corporations which (quite literally) hope to cash in on these possibilities.

Whatever the future holds, however, it is clear that we have moved an important step closer to discovering what it will look like with the birth of these twins.


The technology that He reportedly used to alter the genome of the twins was “clustered regularly interspersed palindromic repeats” (or CRISPR-Cas 9, commonly referred to as CRISPR). As Julia Belluz explained in VOX, CRISPR is:

…a tool that allows researchers to attempt to control which genes get expressed in plants, animals, and even humans; to delete undesirable traits and potentially add desirable ones; and to do this more quickly, and with more precision, than ever before.

What makes CRISPR technology so potentially revolutionary is its ability to make genetic alterations quickly, relatively cheaply and with a great deal of accuracy, which is why it is referred to as gene “editing”: in much the same way that a student might edit an essay before handing it in by changing a few words here and there, or by moving or deleting paragraphs, CRISPR allows scientists to remove or add particular genes or gene sequences.

CRISPR-Cas9 is a customizable tool that lets scientists cut and insert small pieces of DNA at precise areas along a DNA strand. This lets scientists study our genes in a specific, targeted way. Credit: Ernesto del Aguila III, National Human Genome Research Institute, NIH

CRISPR-Cas9 is a customizable tool that lets scientists cut and insert small pieces of DNA at precise areas along a DNA strand. This lets scientists study our genes in a specific, targeted way. Credit: Ernesto del Aguila III, National Human Genome Research Institute, NIH (Public Domain)

This technology, and others like it, raise a number of important questions, including: is it safe? If it is safe, what genetic changes should it be used to make? Who will control or regulate the ways in which gene editing is used? What implications might genetic changes made in particular individuals have for the entire human genome? And, finally, will gene-editing technologies lead us to a more egalitarian future, or to one in which social and economic inequalities have become further entrenched by genetic inequalities? I will discuss each of these questions in turn.

First, is this technology safe? The short answer is that we don’t know. The longer answer is that altering one part of an individual’s genome in order to achieve a particular goal (for example, to make that person resistant to HIV infection) may (paradoxically) render that individual more susceptible to other infections, or more susceptible to developing certain kinds of cancer.

For example, mutations in the gene that He altered to make the girls resistant to HIV are associated with a much higher risk of dying of the flu. We don’t yet know what effects He’s alterations will have on those girls, but we can say with certainty that he used them as experimental subjects – which is to say, he didn’t offer them a treatment for an existing condition, but changed their genes in order to see what would happen.


Second, if these technologies – or certain uses of them – turn out to be safe, what alterations should we make using them? Some bioethicists have argued that changes to the genome intended to cure or prevent genetic diseases are ethically legitimate, while interventions designed for enhancements – such as greater height, intelligence or athletic ability – are ethically problematic. They argue we should allow the former, but prohibit the latter.

However, other bioethicists have argued (correctly, I believe) that once we begin to deliberately alter the genome pf individuals, there is no way we will be satisfied with curing or preventing genetic disease. If we can do more, we will do more. Indeed, the alteration He made to the twins can be considered an attempted enhancement: He took healthy embryos and changed them in a way that was designed to make them better.

Using the genetic scissors, illustration by Johan Jamestad, CRISPR

Third, who, if anyone, will control how these technologies are used? At the moment, it is safe to say, no one. Even if some political jurisdictions ban some uses of these technologies, others will allow them. Moreover, even were there widespread global agreement about what changes we should and should not make, there would still be rogue scientists – as many consider He to be – who will do whatever they want.

Fourth, as noted above, CRISPR allows us to make germ-line genetic alterations – changes to the DNA that will not end with the genome of the individual whose genome was altered, but will be passed on to that individual’s descendants. Over time, then, these changes may spread throughout the human genome, and this, too, may have unexpected and unpredictable consequences. Should we make these germ-line changes, and then hope for the best? Or should we try to come to some consensus, right now, about how we will use these tools, and what penalties we might exact on those who refuse to follow these guidelines?

Finally, some bioethicists have argued that, if it turns out these technologies are safe and effective, what they will do is further entrench social and economic inequalities.

The people with the easiest access to them will be those who already have money and privilege, and they will engineer changes in their offspring that will give them additional advantages: they will ensure their children are smarter, better-looking, longer-living and more athletic than the children of those less fortunate. Over time, these positive changes will be concentrated in families who already have wealth and power, and those who are poor will not only be economically impoverished and socially powerless, but gene-poor as well.

Whether you believe these technologies are leading us to a utopian future or a dystopian one probably depends on whether you are an optimist or a pessimist; however, the potential dangers of gene-editing technologies ought to make even the most serene optimists cautious about how they are used.



Rachel Haliburton

Wolfville native
Rachel Haliburton teaches philosophy at the University of Sudbury. Her latest book, The Ethical Detective: Moral Philosophy and Detective Fiction, was published in February by Lexington Books.