Mutations in the genes responsible for amyloid precursor protein (APP), presenilin 1 and 2 (PSEN1, PSEN2) are implicated in the development of early-onset AD [48,49], while factors like aging, diet, lifestyle, and apolipoprotein E4 gene expression exacerbate late-onset AD [50]. The gene discussed is PSEN1; the disease is Alzheimer disease.