FUS and frontotemporal dementia: Pathologically, post mortem brains of people who had FTD are characterized with frontotemporal lobar degeneration (FTLD) and intracellular depositions of three main proteins: RNA-binding protein TDP-43 (~50%), microtubule-associated protein Tau (~40%), and, in rare cases, RNA-binding protein (FUS, 5%) (25).