The bidirectional relationship between these two proteins in signal transduction cascades may account for some -once puzzling- observations that deposits of Aβ and PrP may co-occur in patients with mixed AD and CJD clinical manifestation (Muramoto et al., 1992; Hainfellner et al., 1998; Debatin et al., 2008). This evidence concerns the gene PRNP and Alzheimer disease.