Due to the heterogeneity of symptomatology within the 4R-tauopathies but also because of phenotypic overlap with neurodegenerative diseases caused by differing protein aggregates, like amyloid β and 3R- and 4R-tau in Alzheimer’s disease (AD) or TAR DNA binding protein 43 (TDP-43) proteinopathies, a precise antemortem prediction of the underlying pathology is difficult based on clinical features alone. Here, MAPT is linked to early-onset autosomal dominant Alzheimer disease.