SNCA and Parkinson disease: Immunostaining of α- synuclein was similar in the colonic mucosa and submucosa of iRBD patients and controls, but that of 129-phosphorylated-α-synuclein in submucosa nerve fibers or ganglia was found in 5.3% of 19 PD patients, 23.5% of 17 iRBD patients, and in 0% of controls [137].