PRKN and synucleinopathy: Loss of Parkin function, due to disease-causing parkin mutations, may impair proteasomal degradation of toxic substrates, but may also compromise non-proteolytic ubiquitin-dependent pathways related to protein aggregation, protein sorting or cell signalling [20]–[26]; partial loss of Parkin function, through age-related or pathological alterations in its biochemical properties, may also contribute to neurodegeneration associated with sporadic PD and possibly other synucleinopathies [27]–[29].