SNCA and Parkinson disease: Future studies using antibodies that can detect immature, un-phosphorylated forms of α-synuclein found outside the brain will help us to understand where α-synuclein aggregation begins in prodromal PD [67] In summary, lesional and histopathology-based studies provide moderately supportive evidence for the gut-first model of PD, albeit with several inconsistencies between the existing established evidence.