Contrary to the situation in aged PDAPP/KO mice, δ secretase activity was not increased in young PDAPP/KO female animals at 12 weeks of age (Supplementary Fig. 6e), indicating that induction of δ secretase activity in SORCS2-deficient brains aligns well with the appearance of profound amyloid and tau pathologies. This evidence concerns the gene MAPT and amyloidosis.