MAPT and early-onset autosomal dominant Alzheimer disease: Alzheimer’s disease (AD) is the most irreversible and progressive brain disorder of neurodegenerative disease characterized by the accumulation of extracellular amyloid beta (Aβ) leading to the formation of senile plaques and intracellular tau aggregates that form neurofibrillary tangles (NFTs) in the brain [1,2].