Alzheimer's disease (AD) is a progressive neurodegenerative disorder characterized by early accumulation of amyloid beta (Aβ) plaques, decades before dementia onset,1, 2 and the subsequent spread of tau neurofibrillary tangles (NFTs), which correlates closely with neurodegeneration and cognitive decline.3, 4. The gene discussed is MAPT; the disease is early-onset autosomal dominant Alzheimer disease.