The ubiquitin kinase PINK1 (encoded by PARK6/PINK1) and the E3 ubiquitin ligase Parkin (encoded by PARK2/PRKN) are among >15 PARK-encoded proteins that, when mutated, cause an early onset form of PD (EOPD), accounting for ~5 to 10% of PD cases (3–5). Here, PRKN is linked to Parkinson disease.