Prime editing is a search-and-replace genome editing technology in molecular biology by which the genome of living organisms may be modified. The technology directly writes new genetic information into a targeted DNA site. It uses a fusion protein, consisting of a catalytically impaired Cas9 endonuclease fused to an engineered reverse transcriptase enzyme, and a prime editing guide RNA (pegRNA), capable of identifying the target site and providing the new genetic information to replace the target DNA nucleotides. It mediates targeted insertions, deletions, and base-to-base conversions without the need for double strand breaks (DSBs) or donor DNA templates.
The technology has received mainstream press attention due to its potential uses in medical genetics. It utilizes methodologies similar to precursor genome editing technologies, including CRISPR/Cas9 and base editors. Prime editing has been used on some animal models of genetic disease and plants.