APOE Ɛ4 allele has been particularly investigated in neurodegenerative and cognitive impairment diseases, and indeed, severe COVID-19 and Alzheimer’s disease share common genetic and metabolic pathways via the OAS1 gene and many risk factors strongly overlap (Tisato et al., 2018; Gemmati et al., 2020; Magusali et al., 2021). The gene discussed is APOE; the disease is COVID-19.