As expected from the presence of the proline 301 mutations and the observation that parts of the ordered cores of these filaments are located outside the sequence encoded by the construct that is overexpressed in the biosensor cells, both types of mutant tau seeds were over 50-fold less competent in seeding the assembly of HA-tau297–391 into filaments than tau seeds extracted from AD brains (Fig. 2E). Here, MAPT is linked to Alzheimer disease.