Ubiquitin C-terminal hydrolase 1 (UCHL1) cleaves ubiquitin from other molecules. Genetic knockout of UCHL1 in mice results in a motor neuron degeneration similar to the spontaneous gracile axonal dystrophy (gad) mutant mice. Point mutations in the UCHL1 gene are associated with some forms of human Parkinson's disease. Since UCHL1 is heavily expressed in neurons, it is released in large amounts following injury or degeneration. The detection of UCHL1 in CSF and other bodily fluids can be used as a biomarker.