APOE and Alzheimer disease: The ε4 allele is a strong risk factor for late-onset Alzheimer’s Disease (LOAD), with individuals carrying one APOE ε4 allele having a 3–4-fold higher risk for AD, while those with two ε4 alleles have a 10–15-fold higher risk (Corder et al., 1993; Saunders et al., 1993; Sims et al., 2020).