Corder et al. reported that the APOE ε4 allele increases the amount of amyloid deposition in a gene dose-dependent manner, which was mirrored by their findings that AD frequency was increased among APOE ε4 homozygous individuals compared to those with only one APOE ε4 allele (91.3 versus 46.6%, respectively) (30). Here, APOE is linked to Alzheimer disease.