Definition of deleterious mutation

deleterious mutation (DEH-leh-TEER-ee-us myoo-TAY-shun): A genetic alteration that increases an individual’s susceptibility or predisposition to a certain disease or disorder. When such a variant (or mutation) is inherited, development of symptoms is more likely, but not certain. Also called disease-causing mutation, pathogenic variant, predisposing mutation, and susceptibility gene mutation.