The DEGs shared between the immune responses of COVID-19 and SZ consist of ACVRL1, BDNF, CSF3R, CXCL1, CXCR2, EDN1, and FLT1. DEGs with COVID-19 and LOD include ACVR1C, FGF9, and INHBB. COVID-19 immune response and BD share two DEGs, EGF and IFNAR2. Here, FGF9 is linked to Behcet disease.