Similar α-Synuclein staining in the colon mucosa in patients with Parkinson's disease and controls

Background: The gut is proposed as a starting point of idiopathic IPD, but the presence of α-synuclein in the IPD colon mucosa is debated. Objectives: The objective of this study was to evaluate if α-synuclein in the colon mucosa can serve as a biomarker of IPD. Methods: Immunohistochemistry was used to locate and quantify in a blinded approach α-synuclein in the mucosa from biopsies of the right and left colon in 19 IPD patients and 8 controls. Results: Total α-synuclein was present in all but 1 IPD patients and in all controls; phosphorylated α-synuclein was present in all subjects. There was no intensity difference depending on disease status. Staining of total α-synuclein was stronger in the right colon (p =.04). Conclusions: Conventional immunohistochemistry α-synuclein staining in colon mucosal biopsies cannot serve as a biomarker of idiopathic PD. These findings do not contradict the assumption of disease starting in the colon, and a colon segment-specific risk for disease initiation can still be hypothesized.