For instance, genotyping of cytokine-related single-nucleotide polymorphisms (SNPs), e.g., IL-6 rs1800796 [7], IL-10 rs1800896 [8], TNF-α rs1800629 [9], and IFITM3 rs12252 [10], has shown them to underlie the differential viral virulence and severity of COVID-19. The gene discussed is IFITM3; the disease is COVID-19.