C3 and Ehlers-Danlos syndrome: These include variant genes with parallel impacts or functions like ADAMTS2/F2/PIK3R1 influencing EDS; ADAMTS13/F2/PIK3C3 influencing COVID-19 that impact clotting tissue laxity; LIFR/NLRP3/STAT1/T1CAM1/TNFRSF13B (both) plus C1R/IF1H1/NFKB2 (EDS) and C3/IFR3/NFKB1 (COVID-19) that impact immunity-inflammation; SLC6A2 (EDS) and SLC6A20 (COVID-19) that have transport functions; and POLG/FOXP2/RBM20/WNT10A/ZNF469 (EDS) and POLD4/FOXP4/RBM15/WNT3/ZNF275 (COVID-19) that have DNA polymerase/regulatory functions (Figure 3, Tables S2 and S3).