EOAD with a family link is referred to as familial AD (FAD), most cases of which are linked to autosomal dominant inherited gene mutations: Amyloid precursor protein (APP) (16% of FAD), presenilin 1 (PSEN1) (30%–70% of FAD) and presenilin 2 (PSEN2) (less than 5% of FAD) [11]. This evidence concerns the gene PSEN2 and familial Alzheimer disease.