Fig. 2: Shifted microbial composition across the prodromal and early stages of α-synucleinopathy.

a Principal coordinates analysis (PCoA) of microbial communities across control (n = 108), RBD-FDR (n = 127), RBD (n = 170), and early PD (n = 36) based on Bray–Curtis distance matrix at the genus level. The label of each group indicates group centroid. Boxplots along the axes of PCoA showed the distributions of PCoA1 and PCoA2 between groups. The white line in the box represented median values, while the lower and upper boundaries represented the first and third quartiles, respectively; whiskers extend up to values within 1.5 times of the interquartile range; outliers are plotted as individual points beyond the whiskers. Statistical differences were analyzed using ANOVA (two-sided test) with post hoc test. P values for multiple testing were adjusted by applying Benjamini–Hochberg method. b Principal coordinates analysis of microbial communities between groups with 70% confidence ellipse. The significance of inter-group differences in overall microbial composition was calculated by PERMANOVA with adjustment of age and sex (permutation = 99,999, two-sided test, based on Bray–Curtis distance matrix at the genus level). R² indicated the inter-individual variation explained by grouping factors in PERMANOVA test, and P values for pairwise comparisons were adjusted by applying Benjamini–Hochberg method. RBD REM sleep behavior disorder, RBD-FDR first-degree relatives of patients with RBD, PD Parkinson’s disease, PERMANOVA permutational multivariate analysis of variance, ns not significant. Source data are provided as a Source Data file.