GPC1 and Alzheimer disease: We observed a consistent enrichment of AD associated proteins such as the Aβ specific peptide LVFFAEDVGSNK (sequence corresponds to amino acids 17–28 of Aβ, Fig. 2D–F, J) and other previously detected amyloid plaque proteins such as HTRA1, GPC1, VIM, APOE, CLSTN1 and SYT11 within the top 10 most significant proteins across groups (Table 2).