Eukaryotic gene editing is the targeted alteration of DNA sequences in the nuclear or organellar genomes of eukaryotic cells. Programmable recognition components position an editing activity at a selected genomic site; in CRISPR systems, a guide RNA specifies complementary DNA recognized by a Cas protein ^[1][2]. Nuclease editors introduce DNA breaks that cellular repair processes resolve into sequence changes. Other editing systems combine target recognition with enzymes that modify bases or copy new sequence information into DNA ^[3]. DNA base editors couple a targeting protein to a nucleobase-modifying enzyme, enabling particular base-pair substitutions without requiring a double-strand break. The molecular components, accessible target sequence, and participating repair reactions specify the range of possible edits, including substitutions, insertions, and deletions ^[4].