PSEN1 and Alzheimer disease: However, one of the vCJD cases (vCJD27) with diffuse Aβ deposits in the brain had the PSEN1 p.E318G variant that increases the risk of AD in APOE-ɛ4 carriers [2] and a −48 C/T polymorphism in the PSEN1 promoter that is a genotype associated with an increased risk of AD and an increased Aβ load in the brain [37].