PRNP and Alzheimer disease: Overall, these findings suggest a role for PrPC in protecting from the pathological effects of Aβ peptides that occur in AD, although the requirement of PrPC for Aβ-induced toxicity has been controversial, with some investigators finding that PrPC was not required for the pathological effects of Aβ (Balducci et al., 2010; Calella et al., 2010; Kessels et al., 2010; Cisse et al., 2011).