Fig. 3

PCA performed on plaque-derived fluorescence spectra reveals a subset of conformational space unique to DS. a Overview of the experimental and computational workflow. b PCA of 2673 plaques from 100 DS, AD, and ADNC cases. The concatenated spectra were analyzed by PCA and are plotted in the eigenspace defined by PC2 and PC3. Each data point derives from the concatenated spectra of 3 dyes and represents one plaque. A Gaussian KDE is shown at 30%, 60%, and 90% probability intervals. c–e The PCA data are plotted separately by cohort for clarity. f A 99.5% kernel density estimate computed from either all ADNC spectra (purple) or all AD spectra (green) is shaded. The non-overlapping subset of DS vectors (blue points) indicate Aβ strains that may be unique to DS