MAPT and early-onset autosomal dominant Alzheimer disease: Many neurodegenerative disorders, including Alzheimer's disease (AD), frontotemporal dementia, Parkinson's disease, Lewy bodies dementia, and amyotrophic lateral sclerosis, have in common the accumulation and aggregation of pathogenic proteins such as amyloid‐β (Aβ), phospho‐tau (p‐tau), α‐synuclein, or TAR DNA‐binding protein 43 (Brettschneider et al. 2015; Jucker and Walker 2013, 2018).