Mitochondrial dysfunction is an early sign of many neurodegenerative diseases. 
Very recently, two Parkinson disease (PD) associated genes, PINK1 and Parkin, 
were shown to mediate the degradation of damaged mitochondria via selective 
autophagy (mitophagy). PINK1 kinase activity is needed for prompt and efficient 
Parkin recruitment to impaired mitochondria. PD-associated Parkin mutations 
interfere with the process of mitophagy at distinct steps. Here we show that 
whole mitochondria are turned over via macroautophagy. Moreover, 
disease-associated PINK1 mutations also compromise the selective degradation of 
depolarized mitochondria. This may be due to the decreased physical binding 
activity of PD-linked PINK1 mutations to Parkin. Thus, PINK1 mutations abrogate 
autophagy of impaired mitochondria upstream of Parkin. In addition to 
compromised PINK1 kinase activity, reduced binding of PINK1 to Parkin leads to 
failure in Parkin mitochondrial translocation, resulting in the accumulation of 
damaged mitochondria, which may contribute to disease pathogenesis.