Search-and-remove genome editing allows selection of cells by DNA sequence.

The selection of cells that have acquired a desired gene edit is often done by the introduction of additional genes that confer drug resistance or encode fluorophores. However, such marker genes can have unintended physiological effects and are not compatible with editing of single nucleotides. Here, we present SNIPE, a method that allows the marker-free selection of edited cells based on single nucleotide differences to unedited cells. SNIPE drastically enriches for cells, which have been precisely edited (median 7-fold). We validate the approach for 42 different edits using Cas9 or Cas12a in different cell types and species. We use it to enrich for combinations of substitutions that change missense mutations carried by all people today back to the ancestral state seen in Neandertals and Denisovans. We also show that it can be used to kill cultured tumor cells with aberrant genotypes and to repair heterozygous tumorigenic mutations.