MAPT and early-onset autosomal dominant Alzheimer disease: Tau is predominantly distributed in the axon of healthy mature neurons, but, in Alzheimer’s Disease (AD) and other tauopathies, tau protein is hyperphosphorylated and, aberrantly, moves to the somatodendritic compartment where it aggregates to form paired helical filaments (PFH) (Iqbal et al.