Known polymorphisms in MAPT which confer susceptibility not only for AD and FTD, but other neurodegenerative diseases as well, together with a possible additional novel disease locus near the MAPT gene [188], strongly support the key role of tau protein not only in primary tauopathies but also in the pathogenesis of LOAD and other secondary tauopathies. The gene discussed is MAPT; the disease is Alzheimer disease.