Scientific and legal elements :
There are two types of gene therapy: somatic and germline.
Somatic gene therapy consists in acting on certain non-reproductive cells to eliminate or reduce genetic defects. The effects are limited to the individual treated. Clinical trials are underway with some success in relation to sickle cell disease (genetic disease of the blood) or certain forms of leukaemia.
Germ-line gene therapy involves modifying a gene so that it is then transmitted to the subject’s offspring. This can be done in two ways:
- either on a very young embryo at the zygote stage,
- either on germ cells (gamete producers) or gametes (sperm and eggs) during their formation.
The embryo or gametes on which the research is being conducted are currently manipulated in vitro. Male gametes are removed by masturbation and female gametes are removed by puncture after hormonal stimulation. Intervention on gamete or embryo DNA is performed by inserting, correcting or removing a small, well-defined segment of DNA (CRISPR-Case technique9). This results in a change in the genome of the embryo or future embryo, which is potentially transmissible. In the long term, the genetic heritage of the human species could be gradually modified.
Remember that the gamete formation process (“meiotic recombination”) results, on the one hand, in an individual’s germ cells not having the same genetic sequence as that of his somatic cells, and, on the other hand, in each gamete having a unique genetic code.
If we also take into account the fact that the vast majority of diseases “depend on many genes as well as environmental factors and lifestyles,” we understand that genetic engineering cannot be an easy solution for treating most diseases. However, CRISPR-Cas9 application research in mice has shown promising results in the treatment of Duchenne muscular dystrophy.
Legally, Article 13 of the Oviedo Convention, ratified by France, stipulates that “an intervention intended to modify the human genome may be undertaken only for preventive, diagnostic or therapeutic reasons, and only if it is not intended to introduce a modification in the genome of the descendants”. Germinal gene therapy is therefore prohibited in France today.
However, the Academy of Medicine has proposed authorizing research on germ cells and embryos “when scientifically and medically justified.
Anthropological and Ethical Issues
As Pope Francis recalled, if technique, well directed, can “produce truly precious things for the quality of life of the human being”, it can also give us “a terrible power”, even “an impressive hold over the whole of humanity”. Germ-line gene therapy exposes to such a risk. Here are four points of discernment.
1. General principle of precaution: “We still know too little about genetic interactions and the possible unintended consequences of the modification of the human genome. By eliminating some harmful predispositions, other problems could appear and expose individuals and the human species itself to other risks potentially as serious as those we could solve.
2. Respect for the most vulnerable: prudence calls for international regulation of research and its applications to guarantee, in particular, “respect for vulnerable persons and personal integrity”, “non-discrimination and non-stigmatization” and “protection of future generations”. On the latter criterion, it should be noted that the modification of the genetic heritage of gametes or human embryos in the very early stages of their growth would have consequences for the whole lives of future children. By touching the genetic structure of their body, it is their free development that is conditioned.
3. Banalization of gametes and embryo commodification: gametes are collected and manipulated outside any conjugal relationship. As far as embryos are concerned, both research and the application of gene therapy are carried out within the technical framework of in vitro fertilisation. This means that human embryos will be handled, frozen, sorted and some destroyed. The human embryo is therefore chosified until destruction.
4. Eugenics: “Such manipulations promote an eugenic mentality and introduce an indirect social stigmatization towards those who do not possess certain particular qualities. These manipulations raise the formidable question of “who would determine which of these modifications would be positive and which would not”.
While somatic gene therapy can be welcomed as a promising advance, subject to the precautions common to all research and therapeutic protocols, germline gene therapy raises serious ethical questions, already expressed by some members of the international scientific community.
The proposed difference between freedom of research and control of applications ignores the anthropological issues underlying scientific research and tends to subordinate ethics solely to the criterion of effectiveness. For the reasons stated above, we can say that germline gene therapy today does not offer the qualities necessary for therapeutic action respectful of human dignity and equality between men.
February 1, 2018
 Cellule résultant de la fusion d’un spermatozoïde et d’un ovule. Premier stade de la vie d’un individu.
 Comité International de Bioéthique de l’UNESCO, Rapport du CIB sur la mise à jour de sa réflexion sur le génome humain et les droits de l’homme, 2015, n°103.
 Académie Nationale de Médecine, Rapport « Modifications du génome des cellules germinales et de l’embryon humain », 12 avril 2016.
 FRANÇOIS, Lettre encyclique Laudato Si’, 2015, n°103–104.
 UNESCO, Rapport du CIB…, n°105.
 UNESCO, Rapport du CIB…, n°116.
 Cf. J. HABERMAS, L’avenir de la nature humaine. Vers un eugénisme libéral ?, Gallimard, 2002,
 CONGRÉGATION POUR LA DOCTRINE DE LA FOI, Instruction « Dignitas Personae » sur certaines questions de bioéthique, 2008, n°27.