Similarly, mutations in PARK2 (Parkin, an E3 ubiquitin ligase), PINK1 (PTEN-induced putative kinase 1) and PARK7 (DJ-1, a protein deglycase), which are associated with early onset (age less than 40 years) PD [33, 53], directly or indirectly affect mitochondrial function either by regulating mitophagy (Parkin and PINK1) or protecting mitochondria from oxidative stress (DJ-1) [5, 59]. Here, PRKN is linked to Parkinson disease.