MAPT and behavioral variant of frontotemporal dementia: A key concept in understanding the clinical presentation of bvFTD and PPA is that theanatomical pattern of degeneration – rather than the type of pathology – determinesthe symptoms.24 In bvFTD, earlyselective neuronal degeneration of Von Economo neurons and fork cells has beendescribed.25 Thisselective neuronal loss has been observed in FTLD-tau, FTLD-TDP and FTLD-FUS,suggesting it occurs irrespectively of the abnormal protein.