The promises and perils of gene editing
By Sergio Sharif, June 7, 2021—
In November of 2018, the world gasped in shock. He Jiankui, a scientist from Shenzhen, China, announced the birth of twins Lulu and Nana — the first children to be born from a genetically-edited embryo. Jiankui had kept his work secret to the international science community, which led to outrage amongst a group predicated on collaboration and transparency. Since then, the outcry over Jiankui’s secrecy has largely been forgotten — along with the greater concerns about gene editing. Despite the recent lack of attention, the conflicting promise and ethical challenge of gene editing is ever more relevant.
To understand gene editing and the controversy surrounding it, one must understand what genes are. Genes are the units of heredity, encoded in molecules of deoxyribonucleic acid — DNA for short. Collectively, the entire complement of genes and all other genetic material is referred to as the genome.
To give life, genes must be decoded by an intricate cellular machinery, ultimately leading to the production of proteins. The proteins produced from the genome come together to form the various tissues and structures of the human body. Proteins also have a variety of roles in metabolism and all other facets of cellular function.
As cells grow and divide, they need to replicate their genes. The cellular machinery responsible for this task almost never leaves mistakes in the copied DNA. However, this consistency is challenged by the presence of mutagens, chemicals which damage DNA, often leading to an overwhelming amount of changes which cannot all be repaired. These alterations are referred to as mutations. When mutations occur in ways which change the proteins produced by genes, disease could occur. This is the basis of cancer, where mutations disrupt the regulation of cell growth and division.
Sometimes, mutations can be inherited. These mutations persist over generations and can cause lifelong disease. Hereditary diseases are often difficult to treat and leave little hope for the affected families — such as in Hutington’s disease. Although there are treatments for many genetic diseases, there are no permanent cures. Gene editing is poised to change that.
Gene editing refers to any technology used to deliberately modify a part of the genome by altering genes. Although many gene editing technologies have long been used within the scientific community, a recent innovation brought a far more powerful tool to the world. CRISPR/Cas9, created by scientists Jennifer Doudna and Emmanuelle Charpentier, is far faster, cheaper and more precise than any other gene-editing technology on the market. The discovery of this technology resulted in Nobel Prize wins in Chemistry for Jennifer A. Doudna and Emmanuelle Charpentier last year, as their work allowed for gene editing to be used far more broadly than ever before.
CRISPR is often mentioned in the most recent discourse surrounding gene editing. Jiankui used CRISPR to modify embryos which would later be implanted in prospective parents. CRISPR is so powerful that it acts as a pair of “genetic scissors,” which can target any gene and cut it out of the genome. The gap left in the genome can be left alone, which erases the function of the gene. It can also be a place to insert alternate forms of the removed gene.
Gene editing has been used mostly for improving crops and performing biomedical experiments in animals. These applications have been, for the most part, largely tolerated. However, if used in embryos, changes in the genome can be passed on from generation to generation. Until the invention of CRISPR, scientists kept genetic experimentation far away from research involving human participants — with the notable exception of eugenics.
The now dated ideas of the genetics of human populations once had a heinous use in the field of eugenics. Closer to an ideology than anything else, eugenics was a set of doctrines which lobbied for controlling the gene pool of the human population by dictating who could reproduce and who could not. Eugenics was achieved through the systemic sterilization of those deemed “feeble-minded” or with disease. The goal was to enhance the human population by skewing the gene pool towards “desirable” traits and the eradication of “undesirable” traits. What was considered “desirable” was to be defined by those leading the eugenics movement and writing the laws around it.
Aside from the ethical issues eugenics created, another major problem became apparent. Eugenics was based on pseudoscientific ideas which were later shown to be false. The main assumption was that socially undesirable characteristics and traits, including mental illness, were inherited genetically and were not a reflection of an individual’s upbringing. The erroneous conclusion eugenicists drew from this was that all undesirable traits could be eradicated through the sterilization of those who possessed them, thus preventing them from bearing children with the same inheritable traits.
Once part of many legislations, even in Alberta, eugenics policies are largely a relic of the past. However, gene editing may risk reintroducing the ethical challenges which defined the legacy of eugenics.
With modern technologies, such as in vitro fertilization and preimplantation genetic testing, parents can screen for embryo genomes that predisposes them to both inherited diseases and other genetic errors such as Down syndrome. Embryos possessing errors are often discarded and not used for pregnancy. In some communities, these technologies are considered unethical as they violate the inviolable. Although, amongst broader society, these technologies remain fairly uncontroversial. Gene editing, if applied in the same context, may spread concern far beyond the outspoken minority.
Gene editing presents two main ethical challenges — the potential to cause harm and to create “designer babies.”
First, despite the monumental advances in genetics, medicine and all other fields pertaining to gene editing, much remains unknown. Although the full sequence of the human genome is known and many human genes have been identified, so far, there is only a paucity of knowledge on what the impacts of modifying those genes would be. This situation resembles a similar situation to the eugenics movement, which as mentioned above, caused immense harm on the basis of pseudoscience.
When Jiankui allegedly modified the embryo which would become Lulu and Nana, he deactivated a gene which, when mutated, has been shown to prevent HIV infection. If HIV infection is prevented by gene editing, it might seem that gene editing embryos in such a fashion is ethical. But when Jiankui was forced to explain himself at the Second International Summit on Human Genome Editing — which serves as a forum for the international scientific community to discuss these contentious issues — it became apparent that the greater medical consequences of the gene he edited were either ignored or not fully considered, let alone the ethical implications.
At the first International Summit on Human Genome Editing, a statement was issued to not use edited embryos to start a pregnancy. This conclusion was reached to prevent the hasty action of researchers such as Jiankui. Without the scientific evidence needed to establish the risks associated with altering the genome, gene editing is potentially unethical and dangerous. Otherwise, there is the risk of harm not only to the children who were born from edited embryos, but any future progeny that may come from those children. If genetically editing an embryo would result in any form of harm or death, the entire future of the field would be compromised.
The other main ethical concern — that has much of the media’s attention — is the use of gene editing technologies to enhance human characteristics, which goes beyond treating disease. This is encapsulated in the oft-mentioned term “designer babies.” In a speculated future, some propose that gene editing could be used to not only treat disease but to also augment human capabilities, such as intelligence or strength.
Some believe that the act of gene editing to enhance a person is in itself potentially unethical. The religious community would argue that, like with in vitro fertilization, this violates the inviolable status of the human body. Others suggest that perhaps soldiers could be engineered to be more effective — a concern which Doudna experienced in a nightmare she had — leading her to use her platform to advocate for a transparent and ethical approach to editing the genes of embryos.
Enhancing a human through gene editing requires defining what a favourable trait or characteristic is, as well as what an unfavourable trait or characteristic is. This requires the use of precisely the same language which defined eugenics — and the resemblance is disturbing. Even if those with lesser traits are not sterilized, other ethical challenges arise.
Primarily, there is the concern that the initial rollout of such a technology would be extremely costly. This would mean that the capability to create a ‘better’ child would be exclusive to the rich. Since these enhancements are heritable, all the descendants of the privileged would also have the same modifications. This could widen the disparities that are already seen between socioeconomic classes. Additionally, the autonomy of every individual who descends from a single edited embryo is lost, with their life determined by the potentially misguided actions of previous generations.
However, the ethical problem of “designer babies” is largely speculative. The assumption that complex human traits — governed by both genes and environment — could be modified with a change in DNA is not close to becoming a reality any time soon. Like what was seen in Jiankui’s cavalier actions, even the repercussions of modifying a single gene are not fully understood. The genetic basis for traits such as eye colour, intelligence or strength are far more complicated than the expression of a single protein involved in susceptibility to HIV infection.
As scientists work to understand how the genome gives rise to the complexities of life and the public grapples with the ethics of editing those genes, time presents itself in an ideal way. Given the current policies and opinions on gene editing throughout most of the world, society has time to figure out how this technology will be used ethically. It is an issue not to be ignored — despite the present pandemic the world finds itself in — as its benefits could far outweigh the costs. However, as science advances and gives rise to an understanding of how to modify human traits and characteristics, the lessons of eugenics cannot be forgotten.
Gene editing presents an opportunity to cure many diseases with effects that span generations. It also has many other applications which promise to improve the lives of many. Only through open dialogue, a commitment to not repeating the wrongs of eugenics and the prescience to avoid the harms of tampering with what is misunderstood, will the benefits of gene editing come to bear fruit.