PSEN1 and early-onset autosomal dominant Alzheimer disease: PSEN1 (HGNC: 9508, OMIM: 104311), PSEN2 (HGNC: 9509, OMIM: 600759), and APP (HGNC: 620, OMIM: 104760) are three primary genes involved in familial EOAD (EOFAD).