Of these, five—CRP, TIMP1, LRG1, S100A8/A9, and TKT—were the best-performing markers with AUC > 0.9 and positive LR 12.5–25.9 for distinguishing patients with active AAV from control subjects. The gene discussed is S100A8; the disease is anti-neutrophil cytoplasmic antibody-associated vasculitis.