MAPT and early-onset autosomal dominant Alzheimer disease: Alzheimer’s disease is the most common cause of dementia and is characterized by the accumulation of amyloid-beta (Aβ) plaques and hyperphosphorylated tau proteins in the brain.59 Aβ plaques are precipitated in the extracellular space and form insoluble aggregates that disrupt neuronal function.60,61 Tau pathology involves abnormal phosphorylation of the tau protein, leading to its aggregation into neurofibrillary tangles.