PRNP and Alzheimer disease: Although the role of PrP as a receptor for Aβ and its significance in Alzheimer disease were initially controversial (22, –, 24), considerable data from independent laboratories have accumulated supporting the association between PrP and Aβ oligomers (25, –, 30), whereas the earlier discrepancies could be explained by differences in the preparation of the Aβ oligomers and the models used (31).