APOE and Onset: The most important genetic risk factor for developing late-onset AD (LOAD) is the apolipoprotein E (APOE) genotype, at least in Caucasians, where carriers of one or two copies of the APOE4 allele have a substantial increase in the risk for developing LOAD compared to carriers of the APOE2 or 3 alleles (Hersi et al., 2017; Bejanin et al., 2021).