MAPT and Alzheimer disease: Similar to the infectious isoform of prion protein (PrPSc), aggregates of alpha-synuclein (αSyn), β-amyloid (Aβ), and tau are able to invade the CNS and induce seeded aggregation after peripheral injection in Tg mouse models of PD, MSA and AD [15, 17, 21, 22, 38, 54, 59].