The apolipoprotein (APOE) gene, encoding APOE involved in lipid metabolism, is a well-established risk factor for Alzheimer’s disease (AD) (Corder et al., 1993; Poirier et al., 1993; Kandimalla et al., 2011, 2013; Yu et al., 2014). Here, APOE is linked to early-onset autosomal dominant Alzheimer disease.