One of best documented AD risk genes is apolipoprotein E (ApoE), a protein that binds and transports lipids (Strittmatter et al., 1993), and also likely binds to beta amyloid plaques (Namba et al., 1991; Jiang et al., 2008) which possibly exerts an immune response (Gale et al., 2014). Here, APOE is linked to Alzheimer disease.