MAPT and frontotemporal dementia: Neuropathological examination (see images in Additional File 1) revealed that all FTD-GRN cases exhibited TDP-43 immunoreactivity in both cortical areas, consistent with TDP-subtype A. All FTD-MAPT cases were characterized by tau-positive neuronal inclusions, neuropil threads, and tangles in both cortical areas, with MAPT-variant specific features.