PSEN1 and Alzheimer disease: Many transgenic mouse models have been developed so far, harboring mutations in the APP, presenilin (PSEN1, PSEN2), MAPT genes or in combination (APP/Tau, APP/PSEN1 double transgenic mice, APP/Tau/PSEN1 triple transgenic mice (3xTg-AD) and five transgenic mice (5xFAD).