To determine potential differences in the synaptic proteomes of AD patients vs. control subjects dependent on APOE genotype and brain region, we focused on the protein abundance ratios as calculated by dividing values from AD patients by matched control subjects, subcategorised for APOE3/4 or APOE3/3 genotype, and segregated by brain region (Fig. 3a-c). Here, APOE is linked to Alzheimer disease.