Additionally, this study also found that individuals with the AD risk allele APOE ε4/ε4 had reduced transcriptomic expression of antiviral genes compared to APOE ε3/ε3 AD patients, suggesting that AD patients with the APOE ε4/ε4 genotype may have less active antiviral defense gene expression activities, rendering them more susceptible to SARS-CoV-2 infection. The gene discussed is APOE; the disease is Alzheimer disease.