MAPT and Creutzfeldt Jacob disease: A partial analogy may be found in the observation that more than 30% of sporadic CJD cases involve 2 human prion strains in the same or different brain locations [16, 74, 79, 107] and this type of strain coexistence effect may be heightened in tauopathies; indeed, the view that singular tau strains drive singular clinical entities may need revisiting.