PRKN and Parkinson disease: Mitophagy itself has strong links to PD following the landmark discoveries that PINK1 and Parkin, two other genes mutated in familial PD, sequentially operate to initiate mitophagy in response to mitochondrial depolarisation in cell lines (Narendra et al., 2008; Koyano et al., 2014; Pickrell and Youle, 2015; Yamano et al., 2018).