HTT and Parkinson disease: Depending on the disease, different protein aggregates are found such as α-synuclein (α-syn) in PD, β-amyloid (Aβ) plaques and hyper-phosphorylated tau neurofibrillary tangles (NFTs) in AD, huntingtin (Htt) in HD, superoxide dismutase 1 (SOD1), and TAR DNA binding protein 43 (TDP-43) in ALS and scrapie prion protein (PrPSc) in spongiform encephalopathies [52].