MAPT and Alzheimer disease: The pathology underlying frontotemporal lobar degeneration is equally heterogeneous and involves abnormal accumulation of proteins including microtubule-associated protein tau, transactive response DNA-binding protein with molecular weight 43 kDa (TDP-43), and fused in sarcoma (FUS) protein, while the lvPPA clinical syndrome is most commonly associated with AD pathology (Rademakers et al., 2012).