In some cases, the researchers managed to simultaneously alter both genes within the same embryo, without the catastrophic damage characteristic of CRISPR.
Furthermore, the modifications resulted in a cessation of cell reproduction, making it currently impossible to transfer these embryos for in vitro fertilization.
Sentenced to three years in prison, He Jiankui remains, by his own admission, unrepentant.
The essential difference between the two cases lies in the fact that Egli did not allow any viable embryos to survive—which, for some critics, constitutes precisely the most telling revelation: human embryos are treated as mere experimental material, their survival being the only unforgivable transgression.
It affects not only the individual concerned but also all of their descendants, thus requiring guarantees of a completely different nature.
Dieter Egli's discovery was highlighted by the New York Times on June 4, 2026: unlike classic CRISPR, which proceeds by excising entire segments of DNA—with the considerable risk of chromosomal destruction that has been observed— base editing operates by targeted substitution of individual genetic letters. This second-generation approach allowed Professor Egli's team to successfully modify two distinct genes : the PCSK9 gene , involved in cardiovascular risks, and the HBG gene , which regulates the production of fetal hemoglobin. In some cases, the researchers managed to simultaneously alter both genes within the same embryo, without the catastrophic damage characteristic of CRISPR.
These results, however, remain imperfect. A portion of the treated embryos exhibited a phenomenon of "mosaicism": some cells carried the modified version of the gene , while others carried the original version, a heterogeneity that could lead to serious medical complications. Furthermore, the modifications resulted in a cessation of cell reproduction, making it currently impossible to transfer these embryos for in vitro fertilization.
The Specter of Eugenics
The case inevitably recalls the scandal caused in 2018 by Chinese researcher He Jiankui, who edited the genomes of embryos intended for birth, resulting in the birth of three girls. Sentenced to three years in prison, He Jiankui remains, by his own admission, unrepentant. The essential difference between the two cases lies in the fact that Egli did not allow any viable embryos to survive—which, for some critics, constitutes precisely the most telling revelation: human embryos are treated as mere experimental material, their survival being the only unforgivable transgression.
The commercial nature of the undertaking heightens concerns. The research is funded by Nucleus Genomics , a company known for its controversial advertising campaigns urging parents to conceive their "best baby" through preimplantation genetic screening. Ethicists like Fyodor Urnov of Berkeley University fear that this sophisticated technique will serve less to eradicate hereditary diseases than to satisfy a demand for "improving " the characteristics of the unborn child—intelligence, height, various abilities—thus paving the way for what he calls a "practical manual for baby enhancers."
A Worrying L egal Vacuum
From the perspective of Catholic bioethics, while therapeutic gene interventions on somatic cells can be considered morally permissible—such as the CRISPR treatment for sickle cell disease approved by the FDA in 2023—any modification of the germline remains deeply problematic. It affects not only the individual concerned but also all of their descendants, thus requiring guarantees of a completely different nature. Furthermore, the instruction Dignitatis Personae, promulgated in 2008 by the Congregation for the Doctrine of the Faith and approved specifically by Pope Benedict XVI, is unequivocal: “In its current state, gene therapy on germ cells is morally illicit in all its forms.”
Faced with the acceleration of these advances thanks to artificial intelligence, the conclusion is inescapable: the absence of binding regulation on embryonic research constitutes a legal and ethical gap that civilized societies can no longer afford to ignore, but it remains difficult to put in place safeguards in this area when we have drawn a line under the social Kingship of Our Lord Jesus Christ.
