Fig. 1: Screening for a highly efficient base editor and analyzing its off-target effects.

a Schematic diagram of screening for highly efficient base editors that induce homozygous stop codons in early embryos through direct injection into zygotes. KSOM, embryo culture medium. b The target sequence in EGFP. The PAM sequence and the intended mutant bases are shown in red and yellow, respectively. c, d, e Statistical analysis of on-target C-to-T base conversion (c), indels (d) and adjacent site mutation (e) induced by BE3, Gam-BE4, hA3A-BE3-Y130F, hA3A-eBE3-Y130F, X-BE3, and X-BE4 in EGFP. Data are mean ± s.e.m for the indicated numbers of blastocysts. Detailed data are shown in Supplementary Data 1. P values were determined by Student’s unpaired two-sided t-test. f Number of nonsynonymous mutations detected in E11.5 embryos from five groups. Floating bars show minima to maxima from two biological replicates. P values were determined by Student’s unpaired two-sided t-test; Lists of nonsynonymous off-target mutations are presented in Supplementary Data 2. g Analysis of SNVs detected in two E11.5 embryos with mutant Tyr, Crygc, or/and Dnmt3a by GOIT and off-targets predicted by Cas-OFFinder based on Tyr-sgRNA, Crygc-sgRNA, and Dnmt3a-sg3, indicating no overlapped sites caused by hA3A-eBE3-Y130F. The numbers present the predicted off-target sites or detected SNVs. h The Manhattan plot shows the distribution of all off-target mutations of different groups (Cre and Try-Crygc-Dnmt3a) in the genome. The abscissa is the location of the mutations on the chromosome, and the ordinate is the frequency of each mutation. Each point presents a mutation (SNV or indel), and the different colors indicate different chromosomes. Source data are provided as a Source Data file.