MAPT and early-onset autosomal dominant Alzheimer disease: A prominent feature of Alzheimer’s disease is the accumulation of the amyloid β (Aβ) peptide in the brain in the form of plaques and cerebral amyloid angiopathy (CAA).1 Aggregation of Aβ has been suggested as an early event in the pathophysiology of Alzheimer’s disease, followed by the accumulation of hyperphosphorylated tau, and cognitive dysfunction.