Besides recombinant synthetic strains, brain-derived α-synuclein aggregates obtained from MSA, PD and DLB patients also exhibit distinct seeding activity, propagation patterns and toxicity both when applied to cultured cells (Woerman et al. 2015; Yamasaki et al. 2019; van der Perren et al. 2020) and to animal models (Watts et al. 2013; Prusiner et al. 2015; Rey et al. 2019; van der Perren et al. 2020). The gene discussed is SNCA; the disease is Parkinson disease.