These disease phenotypes were rescued by removing the APP protein in the BACE2 mutation organoids, revealing the protective role of BACE2 in preventing apoptosis induced by Aβ deposition.[167] Mutations in Presenilin 1 (PSEN1) or Presenilin 2 (PSEN2) lead to fAD. Here, PSEN2 is linked to familial Alzheimer disease.