MAPT and early-onset autosomal dominant Alzheimer disease: Tauopathies such as Alzheimer’s disease, frontotemporal dementia and parkinsonism linked to chromosome 17 (FTDP-17), and progressive supra-nuclear palsy (PSP) are diseases characterised by the intra-neuronal spreading of pathological forms of the microtubule associated protein tau through anatomically connected areas of the brain1–3.