The total percentage of COVID-19 patients with variants in UNC13D or AP3B1 was dramatically higher in high-level cytokine group than in low-level group (33.3 vs. 5.7%, P < 0.001), in critical group than in non-critical group (16.7 vs. 5.2%, P < 0.01), in ICU than in non-ICU admission group (16.1 vs. 5.9%, P < 0.05), and in death group than in survival group (21.7 vs. 5.7%, P < 0.01) (Fig. 1C). This evidence concerns the gene UNC13D and COVID-19.