We also observed a weak positive correlation with a Spearman coefficient between the DemTect score and α-synuclein aggregate concentrations (r = 0.221, p < 0.05), and between the RBDSQ score and α-synuclein aggregate concentrations (r = 0.223, p < 0.05), but no other correlations in stool of PD patients, iRBD patients or healthy controls (Supplementary Table 6). This evidence concerns the gene SNCA and Parkinson disease.