HTT and juvenile Huntington disease: Aggregated proteins that are common hallmarks of neurodegenerative diseases, and known autophagy substrates, include amyloid-β [39, 40], that forms amyloid plaques in Alzheimer's disease; HTT (huntingtin) [41], the causative agent in Huntington's disease; and α-syn [42], a major component of Lewy's bodies associated with Parkinson's and Lewy's body dementia.