Gene editing technology, how far can we go? Differences and ethical issues between germline and somatic cells

The ethical and technical issues of germline versus somatic gene editing are explored in light of the first attempt by Chinese researchers to gene-edit a human embryo in 2019. Germline editing is controversial due to issues of human dignity and genetic diversity, but it holds great promise for treating diseases. Somatic cell editing, on the other hand, raises fewer ethical issues and has potential applications beyond therapeutic purposes. Legal standards need to be established for each.

 

In April 2019, Chinese researchers became the first in the world to genetically modify a human embryo using gene editing technology. The case, which involved editing the gene for beta-thalassemia major, Hemoglobin-B, in an embryo that was unable to give birth normally, sparked global controversy. Seventeen prominent scientists, including Nobel laureate David Baltimore, penned an editorial in Science stating that “scientists should abandon research that attempts to modify the genome of human embryos. Dr. George Daley of Harvard Medical School, on the other hand, “defends the basic science value of gene editing research in human embryos,” and many scientists agree. Gene editing is expected to be used to treat genetic diseases, and with the technology advancing rapidly through ongoing research, safety concerns are expected to be addressed in the near future. However, many scientists are opposed to the technology because of its potential to modify genes for non-therapeutic purposes. In other words, they are concerned about the potential violation of human dignity.
Gene editing can be applied to both germline and somatic cell modifications. Let’s look at the permissibility of gene editing in both cases. Currently, most countries around the world, including Korea, prohibit germline genetic modification for medical purposes except in special cases based on ethical judgment. Consider the case of buying a prefabricated computer. People pick and choose the CPU, memory, and other specifications to create the computer they like best. If germline modification were allowed and gene editing of human embryos were abused, the target would shift from computers to humans. Factors such as a child’s skin color, height, and intelligence will be the result of choices made according to the parents’ preferences, resulting in the creation of “customized babies”. This process can raise questions about human dignity. Edward Lanpierre, president of the Federation for Regenerative Medicine, and his colleagues warned in Nature that ‘modifying human embryos could be used for non-therapeutic modifications’, adding: ‘We are human beings, not genetically modified mice. Modifying human germ cells violates fundamental ethical standards.
Gene editing also violates a basic principle of nature: genetic diversity. When a species goes extinct in an ecosystem, it destroys the balance and can cause chaos in the ecosystem. To prevent this from happening, all living things create different genes to survive in unexpected situations. However, if gene editing of embryos is allowed, parents will edit their children’s genes, and most people’s preferred traits will be similar. As a result, the genetic diversity of babies will inevitably decrease.

Nevertheless, human dignity and genetic diversity are too great a loss in terms of disease treatment to abandon germline gene editing. Nobel laureate and geneticist Craig Mello said, “I believe that in the distant future, we will be able to prevent cancer, diabetes, and other age-related diseases through germline modification. In fact, thousands of human diseases are linked to changes in specific genes, so gene editing at the embryonic stage has huge implications for disease treatment. Lanphier’s alternative is that existing technology can be used to screen embryos before they implant in the womb, eliminating the cause of the disease without modifying the germline. But as Harvard Medical School geneticist George Church points out, “As life science advances, there are more and more genes involved in a disease. By Lanfear’s logic, most embryos would have to be discarded. With gene editing, we have a better chance of getting healthy embryos,” he countered.
Few would argue with the idea that germline gene therapy has a role to play in the treatment of genetic diseases. It would be foolish to completely ban germline gene editing on ethical grounds. Rather, it is ethically problematic to leave diseases untreated in situations where gene editing can be used to treat them. Therefore, legislation should be enacted to allow germline gene editing for therapeutic purposes, but strictly prohibit non-therapeutic modification of genes. This way, germline gene editing can be a technology that meets ethical standards while still benefiting humanity.
The consequences of gene editing in embryos can be passed on to future generations. Somatic cell modification, on the other hand, is not considered a serious technology because it doesn’t involve genetic issues. Currently, gene editing is being used for somatic cell modification, and one biotech company is using it to remove a gene that the human immunodeficiency virus needs to invade cells. Somatic cell modification does not raise issues of human dignity or genetic diversity. It does not undermine the irreplaceable value of each individual human being. In terms of genetic diversity, somatic cell modification does not harm genetic diversity because it does not affect future generations.
The concern with somatic gene editing is that it could widen the gap, allowing wealthier people to replace inferior traits with superior ones through non-therapeutic modification of their genes, while poorer people retain inferior traits due to economic hardship. However, this is not a sufficient basis for a ban on somatic cell modification. Gene editing is similar to plastic surgery, which is more common among those who can afford it, but there are no legal sanctions. In the same way, there is no right to prevent the use of fairly priced and ethically sound technologies. Therefore, somatic gene modification, whether for therapeutic or non-therapeutic purposes, should be free from legal restrictions.
If somatic gene editing is not ethically problematic, why is germline modification necessary? Somatic gene modification techniques have difficulty targeting defective genes. On the other hand, at the embryonic stage, only a small number of cells are present, which increases the chances of a cure. Therefore, many scientists support gene editing in embryos, but argue that it needs to be discussed on an ethical level.
So far, we’ve discussed the permissible scope of germline and somatic gene editing. The different circumstances of somatic and germline gene editing require different legal standards. As Edward Lanphier of the Alliance for Regenerative Medicine and four co-authors told Nature, “We need to make a clear distinction between whether the target of gene editing is somatic or germline cells. As many scientists are calling for a change in the law to allow gene editing research, we hope that the law will be changed soon so that people can benefit from gene editing.