TARDBP and primary progressive aphasia: The major molecular histopathological associations differ between the major syndromes of PPA [22, 23••, 36, 37•]: nfvPPA is most often associated with primary tauopathies, svPPA is closely associated with TDP-43 (type C) pathology, and lvPPA with Alzheimer pathology, leading to the proposal that the PPA may constitute ‘molecular nexopathies’ [2], i.e. specific conjunctions of macroscopic network characteristics and pathogenic protein properties.