USP30 and Parkinson disease: Mitochondrial dysfunction, reactive oxygen species (ROS), proteasome dysfunction and neuroinflammation are implicated in PD [23–26], as the mutations or changes of genes related with these processes, such as PINK1, Parkin, DJ-1, SNCA, UCHL1, LRRK2, TRIM24, MUL1 and USP30, are found to be widely present in PD [27–29].