APOE and Alzheimer disease: ApoE exists in three variants, ApoE2, E3, and E4, with ApoE4 being the most risky allele in the sporadic form of AD (Hayashi et al., 2002; Morrow et al., 2002; Leoni et al., 2010; Youmans et al., 2012; Tai et al., 2013; Oikawa et al., 2014; Wood et al., 2014; Chang et al., 2017; Lin et al., 2018; Fernandez et al., 2019; Lanfranco et al., 2020; Lee et al., 2021; de Leeuw et al., 2022).