MAPT and Alzheimer disease: An overwhelming majority of AD cases is late‐onset (approximately 95%), and both early and late‐onset AD share similar clinical phenotypes (i.e., severe memory loss and cognitive decline accompanied by changes in mood and behavior) (Reitz et al., 2011) and similar biological hallmarks (i.e., β‐amyloid plaques, neurofibrillary tangles of hyperphosphorylated tau, and progressive neurodegeneration in multiple brain regions) (Serrano‐Pozo et al., 2011).