Genetic factors play a significant role in AD as heritability was estimated to range 60–80% (Gatz et al., 2006): the strongest common genetic risk factor for AD is the APOE-ε4 allele, and large collaborative GWAS have identified 41 additional common variants associated with a slight modification of the risk of AD (Sims et al., 2017; Jansen et al., 2019; Kunkle et al., 2019; de Rojas et al., 2021). Here, APOE is linked to Alzheimer disease.