A series of studies and meta‐analysis (Gough et al., 2011; Llorca et al., 2008; Ridge et al., 2013; Shao et al., 2017) showed that apolipoprotein E gene (APOE) ε4 is the well‐known risk factor for sporadic AD, including early‐onset AD (EOAD) and late‐onset AD (LOAD). This evidence concerns the gene APOE and Alzheimer disease.