PSEN1 and Alzheimer disease: A study conducted by Raygani et al. found that apart from ApoE 4, increased ApoB and decreased ApoA1 are associated with Alzheimer's disease [46]. Early-onset AD has also been associated with mutations in the genes coded for enzymes and transporters involved in beta-amyloid metabolisms, such as APP, PSEN1, and PSEN2.