PSEN1 and Alzheimer disease: The most impactful one would be anticipated to be the reduction of the latter (i.e., PSEN1 and PSEN2 complexes), as they have been found to be increased in the cerebrospinal fluid of AD patients (Garcia-Ayllon et al., 2013) and to generate the main source of the intracellular Aβ-pool (Sannerud et al., 2016), respectively.