SNCA and Parkinson disease: Additionally, it is plausible that probiotics could influence PD progression given the reported influence of the gut microbiota on various pathways that are potentially implicated in the pathogenesis of PD including inflammation (Tamtaji et al., 2019; Castelli et al., 2020) and alpha synuclein aggregation (Chen et al., 2016), but more work in this field is needed.