MAPT and Parkinson disease: The predominant misfolded proteins found in AD are amyloid-β (Aβ) and tau, in FTD tau and TAR DNA-binding protein 43 (TDP-43), in PD α-synuclein (α-syn), and in ALS TDP-43.74, 75, 76, 77, 78 Although in their native forms, these proteins differ considerably in size, subcellular localization, and function, they can all aggregate into large fibrils called amyloids.