PSEN2 and Alzheimer disease: Among these forms, presenilin-1 (PSEN1) (MIM #104311), presenilin-2 (PSEN2) (MIM #600759) [2–5], and amyloid protein precursor (APP) (MIM #104760) mutations [6–8] and duplications [9] cause autosomal-dominant EOAD (AD-EOAD), the prevalence of which is estimated to be 5.3 per 100,000 persons at risk [1].