MAPT and early-onset autosomal dominant Alzheimer disease: Neurodegenerative tauopathies, including Alzheimer’s disease (AD), are characterized by the intraneuronal accumulation and pathological neuron-to-neuron spread of hyperphosphorylated aggregated tau protein, along with elevated extracellular levels of soluble hyperphosphorylated tau, measurable in the cerebrospinal fluid (CSF) and plasma (1).