A clinically and pathologically heterogeneous type of frontotemporal lobar degeneration has
abnormal tau pathology in neurons and glia (FTLD-tau). Familial FTLD-tau is usually due to
mutations in the tau gene (MAPT). Even FTLD-tau determined by MAPT mutations has
clinical and pathologic heterogeneity. Tauopathies are subclassified according to the
predominant species of tau that accumulates, with respect to alternative splicing of MAPT,
with tau proteins containing three (3R) or four repeats (4R) of~ 32 amino acids in the …

Frontotemporal lobar degeneration (FTLD) is the second most common cause of presenile
dementia. Three main clinical variants are widely recognized within the FTLD spectrum: the
behavioural variant of frontotemporal dementia (bvFTD), semantic dementia (SD) and
progressive non-fluent aphasia (PNFA). FTLD represents a highly heterogeneous group of
neurodegenerative disorders which are best classified according to the main protein
component of pathological neuronal and glial inclusions. The most common pathological …