The levels of plasma APOE may be important for the endososomal function as APOE ɛ4 carriers have lower levels of plasma APOE4 protein that could predispose them to AD.25 However, APOE genotype does not influence the metabolism of plasma Aβ peptides in young persons without memory deficits.26 In addition, APOE ɛ4- but not ɛ4+ AD participants showed positive relationships between plasma Aβ1–40/Aβ1–42 and PiB uptake.27 This evidence concerns the gene APOE and Alzheimer disease.