ATG5 and Parkinson disease: Ubiquitin-protein aggregates are also cleared through autophagy pathway and one of the characteristic of autophagy malfunction is the increase of ubiquitinated proteins, as it has been reported for different neurodegenerative diseases such as Alzheimer's, Parkinson's, and Huntington's diseases (AD, PD, and HD) as well as the genetically deficient Atg5 and Atg7 knockout mice.