Fig. 1: Modeling of APP and NPTX2 protein levels in DS CSF by estimated year of symptom onset.

A, B Levels of the amyloid precursor protein (APP), located on chromosome 21, in DS (red) and control (blue) cerebrospinal fluid (CSF) (A), and the difference in APP levels between DS and controls (B), by estimated year of symptom onset (EYO). One outlier was removed from A for visualization purposes. C, D CSF levels of neuronal pentraxin-2 (NPTX2), a synaptic protein, in DS and controls (C), and the difference between NPTX2 levels in DS and controls (D). Two outliers were removed from C for visualization purposes. Solid lines indicate the mean protein level; shaded areas indicate the 99% credible interval. Periods of significant difference between DS and controls are highlighted in (B, D) (red indicates significantly increased levels in DS, blue indicates significantly decreased levels in DS). Shaded EYO values on the x-axis indicate periods of lower confidence estimates due to the smaller number of participants over the indicated EYO range. Plots for other proteins are provided in the Supplementary Information.