(A) DNA double-strand breaks generated by CRISPR/Cas9 and sgRNA are repaired by nonhomologous end joining (NHEJ) or, in the presence of a donor template, by homology-directed repair (HDR). The Cas protein recognizes the DNA by the protospacer adjacent motif (PAM). Base editors are generated by fusion of nCas9 or dCas9 with the cytidine deaminase APOBEC1 for cytidine base editors (CBEs) to convert nucleotide C/G to T/A within a 5-bp activity window located in the spacer sequence (108). Similarly, fusion with adenosine deaminase TadA produces adenine base editors (ABEs) to convert nucleotide A/T to G/C (109). Prime editors (PEs) are generated by fusion of nCas9 or dCas9 with reverse transcriptase to perform targeted small insertions, deletions, and base changing in a precise way (28). (B) DMD patients with deletion of exon 50 in the DMD gene have an out-of-frame mutation. (i) Double-cut myoediting results in single- or multi-exon deletion. (ii) Single-cut sgRNA myoediting precisely designed at splice sites (e.g., splice acceptor site [SAS]) restores the correct ORF by both exon skipping and exon reframing events. (iii) Nucleotide editing can be accomplished by BEs or PEs, correcting nonsense mutations. Shaded area highlights different myoediting approaches. Exons encoding ORF are shown in blue. Exons with stop codon are shown in red. The corrected exon is shown in green.