PSEN1 and Alzheimer disease: Generally, FAD occurs due to mutations in presenilin 1 (PSEN1), presenilin 2 (PSEN2), and APP genes through β-secretase (BACE-1) and γ-secretase instead of α-secretase leads to unwanted assembly and accumulation of Aβ peptides in the brain, [11], thereby causing AD pathogenesis [12].