SNCA and Parkinson disease: Prusiner et al. originally reported that TgM83+/– mice expressing human A53T α-synuclein when inoculated with MSA, but not PD, brain homogenates developed neurodegeneration, suggesting that a distinct strain of α-synuclein displays prion characteristics during the development of MSA (Watts et al., 2013; Prusiner et al., 2015).