PSEN1 and Alzheimer disease: 5XFAD is a mouse model of early-onset AD that harbors five Aβ precursor protein (APP) and presenilin (PSEN) mutations linked to familial forms of AD (i.e., APP KM670/671NL (Swedish), APP I716V (Florida), APP V717I (London), PSEN1 M146L, and PSEN1 L286V) leading to a robust production of toxic Aβ peptides, amyloid plaque deposition, synaptic and neuronal loss, and memory deficits14–16.