We can distinguish three basic types of FTLD depending on the hallmark pathological protein: (1) FTLD-tau (characterized by tau-positive inclusions), (2) FTLD-TDP (with TDP-43 inclusions), and (3) FTLD-FUS (having FUS-positive inclusions); although, a small proportion of FTD cases do not express any of the above-mentioned proteins. The gene discussed is MAPT; the disease is frontotemporal dementia.