In the past decade, imaging biomarkers, including hippocampal volume in structural magnetic resonance images (MRI), temporoparietal glucose hypometabolism, neocortical Aβ, and medial temporal and neocortical tau deposition in PET images have been used to stage AD and understand the associated cognitive decline (Besson et al., 2015; Jack et al., 2018). The gene discussed is MAPT; the disease is Alzheimer disease.