The ε2 and ε4 alleles of the apolipoprotein E (APOE) gene are associated with Alzheimer disease (AD) risk. Although nearby genetic variants have also been shown to be associated with AD, including rs2075650 in the TOMM40 gene and rs4420638 near the APOC1 gene, it is unknown whether these associations are independent of the ε2 and ε4 alleles.