[Enhancement can do harm]

Inactivation of the CCR5 gene by CRISPR editing in human embryos, as recently attempted in China, was touted as a positive change for the babies involved since it was expected to impart resistance to HIV infection. However, it turns out that the absence of CCR5 is not neutral but actually decreases fitness, as shown by survival analysis of population data in the UK biobank. This underlines the pitfalls of genetic enhancement, and emphasizes that any germline modification must be preceded by in-depth studies to exclude unforeseen negative effects. ‡.

[CRISPR babies: technology and transgression]

Analysing the data recently presented by Jiankui He and assuming that it is authentic shows that the goal of abolishing the expression of CCR5 may have been reached for one of the resulting twins, although this remains to be proven. However, the canonical delta32 mutation has not been achieved. The various preliminary experiments and controls give some confidence that major off-target modifications have not occurred; again, this is difficult to exclude. Clearly, the requirements of perfect technical mastery of the process have not been met, to say nothing of the requirements for complete transparency and full societal approval.