Mutations in the APP, presenilin 1 (PSEN1) and presenilin 2 (PSEN2) genes can cause Familial AD (FAD), which is typically associated with early-onset (<65 years) AD (Selkoe, 2001; De Strooper and Annaert, 2010; Tcw and Goate, 2017). Here, PSEN1 is linked to Alzheimer disease.