MiRNAs that were downregulated in serum of COVID-19 patients mainly target genes promoting angiogenesis (e.g., VEGFA, ANGPT2, COL4A1, FGF2, ZEB1), apoptosis, autophagy, stress response (e.g., ATG12, ATG14, ATG2B, SOD2, TXNIP), and inflammation (e.g., CXCL9, CXCL10, IL1R1, TNF). The gene discussed is CXCL9; the disease is COVID-19.