Hence, animal models of AD are genetically engineered to induce the overexpression of genes that are implicated most commonly in FAD, such as APP and PS1 (encoding presenilin 1, which is the catalytic component of the Aβ peptide-producing complex gamma secretase) (Sasaguri et al., 2017; Gerakis and Hetz, 2019). Here, APP is linked to Alzheimer disease.