PSEN1 and Alzheimer disease: Mutations in the APP, presenilin-1 (PSEN1) and presenilin-2 (PSEN2) genes have been identified to be causative in AD, particularly FAD, while apolipoprotein E (APOE) and microtubule-associated protein Tau (MAPT) genes are thought to increase the risk of late onset AD (Lanoiselee et al. 2017).