There are predominantly two pathologic FTD subtypes (i.e., frontotemporal lobar degeneration, FTLD): FTLD-Tau, which has inclusions of the microtubule-associated protein tau, and FTLD-TDP, which has TAR DNA-binding protein 43 (TDP-43) inclusions (Irwin et al., 2015). The gene discussed is MAPT; the disease is frontotemporal dementia.