The technique has ethical difficulties human embryo cloning and germline modifications
Over the last few months, several articles have been published reporting genome editing experiments on human embryos (See HERE ). Now, a team of Chinese researchers has published a new study stating that in addition to modifying the genome of the embryos, they had obtained them through cloning.
The team used genome editing to correct a mutation that causes a potentially fatal blood disorder, β-thalassemia. This new study is novel in two aspects.
- Firstly, it uses an innovative modification of the CRISPR-Cas9 technique, which allows very specific mutations to be induced, exchanging one letter of the DNA for another (see HERE ). Until very recently, genome editing was produced by introducing DNA breaks as the first step to gene correction, but this method was inefficient and caused numerous errors. In contrast, this new approach enables the direct, irreversible conversion of one DNA base into another in a programmable manner, without requiring previous DNA cleavage or a donor template.
- The second novelty of the study is that, for the first time, the mutation responsible for a “recessive” disease, i.e. caused by having two defective copies of a gene (and not only one), has been edited. Since it would be difficult for the researchers to find dozens of embryos with this rare double mutation, the team produced embryonic clones from the skin cells of a patient with the disease.
Ethical approach to human cloning for research
From an ethical point of view, this work presents very serious concerns. On one hand, the destruction of embryos is completely unacceptable ( see the Anthropological status of the human embryo. Likewise, the cloning of human beings is ethically unacceptable (see HERE), as it violates the dignity of persons, a fact that is exacerbated when the cloning is done with the sole purpose of obtaining individuals for use in research before subsequent destruction, as is the case of the study discussed. Finally, it should be mentioned that, today, the risks of germline gene editing are so many and so serious, that the wave of studies in this respect on human embryos makes no sense, when there still remains so much to perfect in animal models.