MAPT and semantic dementia: In 1990s, linkage analysis in families affected by frontotemporal dementia with parkinsonism (FTDP) and pathologically characterized by tau deposits in neuronal and glial cells indicated that the candidate gene lied at 17q21–22, where MAPT is located, and in 1998 sequencing analysis finally revealed pathological mutations of MAPT (FTDP linked to chromosome 17-tau, FTDP-17T).