Hyperphosphorylated tau protein and fibrillar beta‐amyloid (Aβ) are the hallmark neuropathologies of Alzheimer's disease, with neurofibrillary tangles of tau accumulating both intra‐ and extracellularly and Aβ plaques largely found in the extracellular space (Jack et al. 2018a). Here, MAPT is linked to early-onset autosomal dominant Alzheimer disease.