SNCA and Parkinson disease: In the author’s opinion, given the numerous potential pathogenic mechanisms of PD mentioned earlier (Jankovic and Tan, 2020; Bloem et al., 2021), it is conceivable that the relevant mechanisms at play such as alpha synuclein aggregation and propagation may differ to varying degrees from one patient with PD to the next depending on their specific genetic predispositions and environmental exposures.