Tau aggregates must meet a number of criteria in order to be classified as bona fide strains including existing as diverse conformers that can be stably propagated through living organisms, possessing variations in biochemical characteristics such as seeding efficiencies, toxicity, solubility, and aggregate size, and the ability to produce an array of pathologies, which would account for the range of symptoms underlying the tauopathies. The gene discussed is MAPT; the disease is tauopathy.