TBK1 and Parkinson disease: Notably, decreased mitophagy is widely and tightly associated with neurodegenerative diseases, including Parkinson's disease (PD) and amyotrophic lateral sclerosis (ALS), since loss of function mutations in Parkin (gene product of PARK2) and PINK1 (gene product of PARK6) cause PD, and loss of function mutations in OPTN (gene product of ALS2) and TBK1 (gene product of ALS-FTD4) cause ALS [1,11].