CRISPR-Cas9 induces large structural variants at on-target and off-target sites in vivo that segregate across generations.

Journal or Publishing Institution: Nature communications

Study: https://www.nature.com/articles/s41467-022-28244-5

Author(s): Höijer, I., Emmanouilidou, A., Östlund, R., van Schendel, R., Bozorgpana, S., Tijsterman, M., Feuk, L., Gyllensten, U., den Hoed, M. and Ameur, A.

Article Type: Peer Reviewed Study

Abstract:

CRISPR-Cas9 genome editing has potential to cure diseases without current treatments, but therapies must be safe. Here we show that CRISPR-Cas9 editing can introduce unintended mutations in vivo, which are passed on to the next generation. By editing fertilized zebrafish eggs using four guide RNAs selected for off-target activity in vitro, followed by long-read sequencing of DNA from >1100 larvae, juvenile and adult fish across two generations, we find that structural variants (SVs), i.e., insertions and deletions ≥50 bp, represent 6% of editing outcomes in founder larvae. These SVs occur both at on-target and off-target sites. Our results also illustrate that adult founder zebrafish are mosaic in their germ cells, and that 26% of their offspring carries an off-target mutation and 9% an SV. Hence, pre-testing for off-target activity and SVs using patient material is advisable in clinical applications, to reduce the risk of unanticipated effects with potentially large implications.

Keywords: CRISPR-Cas9, on-target, off-target, in vivo

Citation:

Höijer, I., Emmanouilidou, A., Östlund, R., van Schendel, R., Bozorgpana, S., Tijsterman, M., Feuk, L., Gyllensten, U., den Hoed, M. and Ameur, A., 2022. CRISPR-Cas9 induces large structural variants at on-target and off-target sites in vivo that segregate across generations. Nature communications, 13(1), pp.1-10.