The highly penetrant mutations in the genes coding for amyloid precursor protein (APP), presenilin 1 (PSEN1), and presenilin 2 (PSEN2) are considered responsible for an earlier onset (early-onset, EOAD) or familial form, accounting for 5 to 10% of AD cases according to different estimates [6]. This evidence concerns the gene PSEN1 and Alzheimer disease.