The Chinese twins born last year from embryos genetically modified by the "CRISPR" molecular scissors probably have unexpected mutations in their genome as a result of this manipulation. This information was revealed by an American journalist on December 3 after obtaining an unpublished version of the study detailing the experiment.
The announcement shocked the world in November 2018 when scientist He Jiankui revealed in Hong Kong that he had modified embryos, as part of an in vitro fertilization for a couple, in an attempt to create a mutation in their genomes that would give them natural immunity to the AIDS virus during their lifetime. The news had caused an outcry because the procedure used had no medical justification, presented serious health risks and contravened the most elementary ethical rules.
Twins were born, named Lulu and Nana, but they and their parents have remained anonymous, and it is not known what became of them.
He Jiankui's experiment had been strongly condemned by the international scientific community and his country's authorities, and the case had rekindled calls for a ban on "baby Crisprs".
The manuscript of the study revealed
A journalist from the MIT Technology Review received the manuscript of the study that He Jiankui has attempted to have published by prestigious scientific journals, detailing his method and results. But the text of the study confirms what many experts suspected: according to geneticists interviewed, it does not actually show that the attempted mutation on part of the CCR5 gene actually succeeded. The study claims that the mutation that was successful is "similar" to the one that confers immunity, not identical.
In addition, data included in the appendix show that the twins have mutated elsewhere in their genome, and probably differently from cell to cell, making the consequences unpredictable.
Why not enjoy unlimited reading of UP'? Subscribe from €1.90 per week.
"CRISPR" is a revolutionary genome-modification technique invented in 2012, much simpler and easier to use than existing technologies. But the scissors often cut next to the target location, and geneticists repeat that the technology is still far from perfect for therapeutic use.
" There are a lot of problems with the CRISPR twins. All the established ethical principles were violated, but there is also a big scientific problem: he did not control what CRISPR was doing, and this created a lot of unintended consequences. ", said genetics professor Kiran Musunuru of the University of Pennsylvania in a recent interview with AFP.
In the MIT Technology Review, geneticist Fyodor Urnov says: " However, the research was incomplete and the manuscript fails to mention a key point: the cells taken from early embryos for testing did not actually contribute to the twins' bodies. The remaining cells, those that would multiply and develop into twins, could also have had off-target effects, but there would have been no way to know this before the pregnancy began.. "He adds: " A blatant distortion of the real data which can, once again, only be described as a blatant lie. It is technically impossible to determine whether a modified embryo "did not exhibit any off-target mutations" without destroying that embryo by inspecting every cell in it. This is a key problem for the whole field of embryo editing, a problem that the authors are sweeping under the rug here. "