Synthetic rescue (or synthetic recovery or synthetic viability when a lethal phenotype is rescued [1][2]) refers to a genetic interaction in which a cell that is nonviable, sensitive to a specific drug, or otherwise impaired due to the presence of a genetic mutation becomes viable when the original mutation is combined with a second mutation in a different gene.[1] The second mutation can either be a loss-of-function mutation (equivalent to a knockout) or a gain-of-function mutation.[2]
Synthetic rescue could potentially be exploited for gene therapy, but it also provides information on the function of the genes involved in the interaction.