Tauopathies differ in (i) the isoforms of tau (3R, 4R, or both) found embedded into amyloid fibrils, (ii) the presence or absence of mutations in the MAPT gene, particularly within the MTBR, such as the P301L or P301S mutations in frontotemporal dementia linked to Parkinsonism (FTDP), or in intronic regions affecting RNA splicing, (iii) the folds of the filament core, and (iv) the spatiotemporal patterns of tau pathology propagation42. The gene discussed is MAPT; the disease is tauopathy.