Compared with those in the ANCA-IIPs group, neutrophil levels (6.79 vs 4.68, p = 0.011), ESR (69 vs 17, p < 0.001) and CRP (23.40 vs 2.44, p < 0.001) were significantly higher in the MPA-ILDs group. The gene discussed is CRP; the disease is microscopic polyangiitis.