PRNP and Alzheimer disease: Thereafter, we tested binding to PrP using a sensitive solid-phase ELISA-like assay, PrP deletion constructs, mouse primary neurons that express or lack PrP, iPSC-derived human neurons (iNs) with and without CRISPR-mediated deletion of PRNP, and aqueous extracts of AD, DLB and PiD brains.