SNCA and Alzheimer disease: Each disorder is characterized by the misfolding of one or more specific proteins: amyloid-β (Aβ) and Tau (MAPT) in AD, α-synuclein (α-syn/SNCA) in PD, Huntingtin (HTT) in HD, superoxide dismutase 1 (SOD1), TAR DNA binding protein 43 (TDP-43/TARDBP), FUS RNA-binding protein (FUS) and dipeptide repeat proteins (DPRs) translated from C9orf72-SMCR8 complex subunit (C9orf72) in ALS, and the prion protein (PrP/PRNP) in prion diseases (Dobson, 2017; Eisenberg and Sawaya, 2017).