MAPT and early-onset autosomal dominant Alzheimer disease: Alzheimer disease (AD) is a common neurodegenerative disease that is marked by the pathologic accumulation of amyloid-beta (Aβ) and tau proteins in the brain.1,2 Although the exact causes of AD are not fully understood yet, it is commonly acknowledged that the development of AD is probably due to a combination of genetic factors, lifestyles, vascular health, and other various risk factors.3