Fig. 1: Overview of genome editors and editing outcomes.

A Cas9 nuclease, cytosine BE (CBE), adenine BE (ABE) and prime editor (PE) are shown, illustrating their mechanisms of action and respective editing outcomes. The Cas9 nuclease (Cas9-WT), guided by a sgRNA, induces a DSB at the target site, leading to DNA repair via nonhomologous end joining (NHEJ) or HDR, resulting in indels. CBE combines nCas9 (D10A) and cytidine deaminase to convert a cytosine (C) to uracil (U), which is repaired as a thymine (T), achieving C-to-T substitutions. The ABE uses nCas9 (D10A) fused with adenosine deaminase to convert adenine (A) to inosine (I), which functions as guanine (G), resulting in A-to-G substitutions. The prime editor (PE) is a more versatile system, using nCas9 (H840A) fused to a RT to directly write new genetic information into the DNA via a pegRNA, enabling a range of modifications, including precise base substitutions, insertions and deletions without the need for DSBs. Each method offers unique editing outcomes, from indel formation with Cas9 nuclease to precise, programmable base edits and structural changes with BEs and prime editors.