Although the known MAPT mutations appear to exclusively cause FTLD-tau pathology, the rare p.A152T variant, first identified in a patient with dementia with behavioural symptoms and unclassifiable tau pathology (Kovacs et al., 2011), was identified as a genetic risk factor for both clinically-defined Alzheimer’s disease and frontotemporal dementia (FTD) spectrum disorders in an initial genetic association study (Coppola et al., 2012). This evidence concerns the gene MAPT and early-onset autosomal dominant Alzheimer disease.