China’s Gene-Edited Baby Experiment Created Unintended Mutations
First, despite claiming in the abstract of their unpublished article that they reproduced the human CCR5 mutation, in reality the team tried to modify CCR5 close to the Δ32 mutation.
As a result, they generated different mutations, of which the effects are unknown. It may or may not confer HIV resistance, and may or may not have other consequences.
Worryingly, they did not test any of this, and went ahead with implanting the embryos. This is unjustifiable.
The Mosaic Effect
A second source of errors could have been that the editing was not perfectly efficient. This means that not all cells in the embryos were necessarily edited.
When an organism has a mixture of edited and unedited cells, it is called a “mosaic”. While the available data are still limited, it seems that both Lulu and Nana are mosaic.
This makes it even less likely that the gene-edited babies would be resistant to HIV infection. The risk of mosaicism should have been another reason not to implant the embryos.
via themindunleashed China’s Gene-Edited Baby Experiment Created Unintended Mutations