In view of the far-reaching implications of the birth of allegedly ‘gene-edited’ twin girls announced by Chinese researcher He Jiankui last month (Nature 563, 607–608; 2018), we urgently need to revisit the use of the term.
It is ten years since the concept of gene editing took off (see, for example, E. E. Perez et al. Nature Biotechnol. 26, 808–816; 2008). This was used to describe just about any DNA modification by exogenous nuclease systems. It now makes more sense to apply it only to deliberate, precise alterations to DNA sequences. Sequences modified haphazardly by cells after the introduction of CRISPR would then be classified simply as random mutations and not as ‘gene edits’.
This is not just a matter of semantics (see also M. O’Keefe et al. Am. J. Bioeth. 15, 3–10; 2015). Characterizing He’s claimed mutations to the CCR5 gene as ‘edits’ misleads the public by implying that they were planned and applied with accuracy. It seems, however, that they were the result of random insertions and deletions of DNA. Exaggerating the precision of the process is harmful — in part, because it downplays the potential biological risks associated with random gene mutations in the germline.
Overall, a more-precise definition of genome editing will be helpful in the human reproductive context — in the event of more ‘CRISPR babies’ — and for broader CRISPR-related applications.
Nature 564, 345 (2018)