Our data contribute to the mounting evidence that prion-like transmission of misfolded proteins represents a common process in the pathogenesis of several neurodegenerative diseases, including α-synuclein in Parkinson's disease [9, 17, 63], Aβ and Tau in AD [18, 64, 65], and SOD1 or TDP-43 in ALS [21, 25, 26, 28]. Here, SOD1 is linked to Parkinson disease.