Genome-wide association studies and genome sequencing have identified more than 25 Alzheimer's disease (AD) risk loci, including common, low-risk variants and rare moderate risk variants, in addition to the classical risk variants in the apolipoprotein E (APOE) gene (Guerreiro et al., 2013b, Hollingworth et al., 2011, Jonsson et al., 2013, Lambert et al., 2013, Naj et al., 2011, Pimenova et al., 2018, Steinberg et al., 2015). Here, APOE is linked to Alzheimer disease.