The four most promising biomarker genes to predict clinical outcome in COVID-19 patients were C-type lectin domain family 12 member A (CLEC12A, AUROC = 0.908, 95% CI = 0.822–0.994), rhesus blood group CcEe antigen (RHCE, AUROC = 0.875, 95% CI = 0.774–0.976), C-type lectin domain family 12 member B (CLEC12B, AUROC = 0.863, 95% CI = 0.754–0.972), and acetylcholinesterase (ACHE, AUROC = 0.837, 95% CI = 0.722–0.951). The gene discussed is RHCE; the disease is COVID-19.