Women with APOE ɛ3/ɛ4 have a higher risk of developing MCI and AD compared with men with the same genotype; however, men who are homozygous for APOE ɛ4 are at a higher risk of AD than women who are homozygous for ɛ4 [59,260,261]. The gene discussed is APOE; the disease is Alzheimer disease.