The absence of binding in the vitro autoradiography images of FTLD-TDP cases is in line with a recent study in which in vitro [3H]AV1451 autoradiography on frontal and temporal cortical cryosections of SV PPA cases as well as C9orf72 TDP-43 type B cases also showed no binding [12]. Here, C9orf72 is linked to primary progressive aphasia.