Presenilin 1 (PSEN1) and amyloid precursor protein (APP) are well-established genetic factors associated with early-onset familial Alzheimer’s disease (EOFAD), whereas apolipoprotein E4 (APOE4) is a recognized genetic risk factor for sporadic late-onset Alzheimer’s disease (LOAD). This evidence concerns the gene PSEN1 and early-onset autosomal dominant Alzheimer disease.