APP and early-onset autosomal dominant Alzheimer disease: Three main genes are involved in early‐onset familial AD (EOFAD), APP (HGNC: 620, OMIM: 104760), PSEN1 (HGNC: 9508, OMIM: 104311), and PSEN2 (HGNC: 9509, OMIM: 600759), encoding amyloid precursor protein, presenilin‐1, and presenilin‐2, respectively (Mendez, 2019).