In contrast, the KIR2DL1 + C2 combination was overrepresented in the mild group (45.6% vs. 29.3%, OR = 2.256, 95% CI = 1.252-4.068, p = 0.013), but a difference in the frequency of the KIR2DL1 + C2 pair was not observed in the severe COVID-19 group (33.3%, p = 0.563) (Table S8 and Figure 4D). The gene discussed is KIR2DL1; the disease is COVID-19.