Highly efficient base editing at PCSK9 and normal human embryo development.

Authors

Stepan Jerabek, Chanju Jung, Michelle Kappy, Qiaojin Zhao, Julie Sung, Ning Wang, Euihyun Kim, Jimin Kim, Marcos Iuri Roos Kulmann, Madeleine Bliss King, Mitchell John McAndrew, Meng Li, Sakshi Bhatele, Melisa Isado, Hong-Su Jang, Michal Dolezal, Robert Prosser, Shuangyi Xu, Gue-Ho Hwang, Iva Pichova, Jia Xu, Diego Marin, Jae-Sung Woo, Sangsu Bae, Nathan Treff, Audrone Lapinaite, Dieter Egli

Published in

Nature. Sep 09, 2026. Epub Sep 09, 2026.

Abstract

Cas9-based tools enable programmable DNA lesions for studying repair outcomes, gene function, and genome correction. In human embryos, Cas9-induced DNA double-strand breaks are genotoxic, causing frequent aneuploidy and large deletions^1,2. Here, we evaluate DNA repair outcomes at nicks and mismatches introduced by base editors at the PCSK9 and HBG loci in human embryos. Delivering ABE8e-V106W as a protein at fertilization achieved editing at all PCSK9 alleles, supporting development to the blastocyst stage and the derivation of homozygous edited stem cell lines. No insertions or deletions were detected, although rare on-target chromosome breakage and chromosomal abnormalities occurred. Nevertheless, editing at bystander and off-target sites was mosaic, and the introduction of the editor as mRNA caused frequent embryo arrest due to guide-independent deaminase activity. Thus, unlike Cas9-induced DNA breaks, base editor-induced lesions are efficiently repaired. However, undesirable consequences for the genome and development can occur, currently precluding clinical use in reproduction.

PMID:
42742174
Bibliographic data and abstract were imported from PubMed on 15 Sep 2026.

Read full publication at:
Please sign in to see all details.

Stats

1-terrible, 9-excellent. How would you rate this publication? Sign in in to submit your rating.

Post a comment

You need to be signed in to post comments. You can sign in here.

Comments

There are no comments yet.