More than 15 different pathologies can underlie FTD and related disorders and it has four major types of pathological features: (1) microvacuolation without neuronal inclusions, (2) microvacuolation with ubiquitinated rounded intraneuronal inclusions and dystrophic neurites FTLD-ubiquitinated (FTLD-U), (3) transcortical gliosis with tau-reactive rounded intraneuronal inclusions, (4) microvacuolation and taupositive neurofibrillary tangles. Here, MAPT is linked to frontotemporal dementia.