PSEN2 and familial Alzheimer disease: Whereas sAD represent a polygenic disorder, fAD is linked to mutations and polymorphisms in genes such as Amyloid precursor protein (APP), Presenilin 1 (PSEN1) or Presenilin 2 (PSEN2) and account for 5%–10% of all AD cases (Bagyinszky et al., 2014).