MAPT and frontotemporal dementia: Patients with mutant MAPT-associated FTD (also known as FTD and Parkinsonism linked to chromosome 17 or FTDP-17) suffer from additional degeneration of brain stem areas including the substantia nigra and demonstrate excessive accumulation of phosphorylated TAU protein (p-TAU) in neurons and also in astrocytes, which undergo pronounced morphological changes in affected brain areas4.