Ubiquitin carboxy-terminal hydrolase L1 (UCH-L1) (EC 3.1.2.15) is a deubiqutinating enzyme . A point mutation (I93M) in the gene encoding this protein is implicated as the cause of Parkinson's disease in one kindred. Furthermore, a polymorphism (S18Y) in this gene has been found to be associated with a reduced risk for Parkinson's disease.