MAPT and early-onset autosomal dominant Alzheimer disease: Tauopathies, such as frontotemporal dementia (FTD) and Alzheimer’s disease (AD), are neurodegenerative diseases characterized by the aberrant accumulation of misfolded, insoluble, and hyper-phosphorylated tau (P-tau) protein within neurons and glia of specific brain regions (Kosik et al., 1989; Goedert, 2004; Morris et al., 2011; Cruts and Van Broeckhoven, 2015; Ghetti et al., 2015; Neumann et al., 2015; Olney et al., 2017).