Compare base editing and prime editing with traditional CRISPR-Cas9.

Traditional CRISPR-Cas9 creates double-strand breaks (DSBs), relying on cellular repair (NHEJ for knockouts, HDR for precise edits requiring donor template). Base editors fuse catalytically impaired Cas9 to deaminases enabling C>T or A>G transitions without DSBs: cytosine base editors (CBE) deaminate C to U; adenine base editors (ABE) deaminate A to I (read as G). Prime editing uses nickase Cas9 fused to reverse transcriptase with pegRNA containing edit template, enabling all transition and transversion mutations, small insertions, and deletions without DSBs or donor templates. Efficiency varies by edit type and cell context. Base/prime editing have lower off-target risks and indel rates but limited edit scope compared to HDR. Selection depends on edit requirements and application.