SNCA and Parkinson disease: Furthermore, MSA brain extracts exhibit distinct infectivity compared to PD or control brain extracts in cultured cells or mice expressing mutant A53T or WT α-synuclein (Lau et al., 2020; Peng et al., 2018; Prusiner et al., 2015; Woerman et al., 2019; Woerman et al., 2015).