When the topic of germline editing arises, most scientists wince. The infamous CRISPR-baby scandal involving the Chinese scientist He Jiankui, who altered human embryos, brought the conversation to the forefront. Editing reproductive cells or embryos not only affects the individual being treated but also introduces permanent changes to their genetic code, which can be passed down through generations—whether beneficial or harmful. As a result, germline editing is banned in most countries, with He Jiankui serving jail time for his actions. Although he was released, his controversial experiment remains a flashpoint for debate in the scientific community.
He’s CRISPR-edited twins, Lulu and Nana, are reportedly growing normally as toddlers, though details of their health remain vague. Despite worldwide condemnation of his methods, He’s work ignited a broader discussion about the future of germline editing. In theory, such edits could be used to eliminate inherited diseases, benefiting entire family lines. But where does the line between disease prevention and designer babies lie? Should gene editing be reserved only for serious illnesses, or can it extend to genetic traits like intelligence or physical appearance?
In a new twist to this ongoing debate, researchers have taken a novel, machine-only approach to evaluate the risks and rewards of germline editing. Using advanced mathematical models, they explored the potential for editing genes related to common, complex diseases such as heart attack, stroke, cancer, diabetes, and depression—diseases that affect millions of people worldwide. The study’s authors didn’t modify any actual embryos; they simply used data and algorithms to predict the effects of genetic changes.
According to the study, adding just 10 protective gene variants could reduce the risk of these diseases by as much as 60 times. The model also predicted several health benefits, such as lowering “bad” cholesterol in those predisposed to heart disease—a concept that is already being tested in clinical trials, like the one from Verve Therapeutics, which is investigating a gene-editing approach to combat cholesterol.
However, not all scientists and ethicists are convinced that germline editing is ready for mainstream application. In a stark counterpoint, an accompanying article written by Shai Carmi (Hebrew University), Henry Greely (Stanford Law School), and Kevin Mitchell (Trinity College Dublin), argued that embryo editing for disease prevention is unsafe and unproven. They raised several pressing concerns, from technological limitations to the societal impacts of potentially tweaking our DNA for future generations. They point out that, even if the technology improves, the broader implications—such as inequality, consent, and genetic discrimination—still require careful consideration.
Carmi, Greely, and Mitchell also warn that the hype around germline editing could lead to misguided policies if not scrutinized carefully. “Given the broad interest in this topic, the work will probably be discussed widely and might ultimately affect policy,” they write. Ethical questions about the extent to which we should intervene in human evolution remain unresolved, and these discussions are critical for shaping the future of gene editing technologies.
While gene therapy has already shown promising results—such as the CRISPR-based treatment approved in the UK in 2023 for sickle cell disease and beta thalassemia—the focus has been on somatic cells. Somatic gene editing affects only the individual patient, and any changes are not inherited by their offspring. In contrast, germline editing affects reproductive cells, meaning any genetic changes would be passed down to future generations. The ethical and societal stakes are much higher with germline editing because it involves altering the human gene pool itself.
The most significant hurdle with germline editing lies in the complexity of common diseases. Unlike single-gene conditions (like sickle cell), many of today’s most prevalent health issues—heart disease, diabetes, and cancer—are polygenic. These diseases result from the interaction of hundreds or thousands of small genetic variations. Each individual gene variant may have only a small effect on health, but when combined, they can significantly increase the risk of disease.
Some scientists are pursuing alternative methods to tackle the issue of polygenic diseases. Polygenic risk scores are already used to identify patients at higher risk for diseases like breast cancer, where multiple gene mutations are involved. Embryo screening via in vitro fertilization (IVF) is already in practice for identifying embryos with a lower polygenic risk for certain conditions. While the expected reductions in disease risk are modest, this method provides a non-invasive option for parents without editing the genome directly.
A more radical approach would be to directly alter the embryo’s genes—specifically by introducing protective gene variants. This was He Jiankui’s approach, though it remains controversial due to the lack of evidence and the unpredictability of gene editing outcomes. If successful, however, such genetic changes could prevent diseases for generations, offering a powerful tool for long-term health improvement. But as with any new technology, the risks—both biological and ethical—cannot be overlooked.
While gene-editing technologies like CRISPR hold great potential, they also bring profound challenges. As the scientific community grapples with the implications of germline editing, it is clear that careful consideration is necessary—both from a technological and ethical standpoint. The future of germline editing depends not only on advancements in science but also on the societal frameworks we establish to govern its use.
Is editing our genetic blueprint the future of healthcare, or is it a Pandora’s box that humanity is not yet ready to open? The answer to that question will shape the trajectory of genetic science for generations to come.
By Impact Lab