SNCA and Parkinsonism: To investigate whether human wild-type alpha-synuclein supports prion-like spreading of pathological alpha-synuclein, we prepared and injected the sarkosyl-insoluble fraction from cortical brain tissue from two patients with MSA, a 51-year-old female and a 59-year-old male, and from two cases of probable iLBD, a 68-year-old female and a 78-year-old male (Table 1), without clinical symptoms of parkinsonism or any other neurological disorder, or phosphate-buffered saline (PBS) as a negative control into the striatum of 6-8-week-old adult Tg(SNCA)1Nbm/J mice (Table 2).