To screen key genes associated with DM-ILD, we extracted 35 common genes from lung disease and skin disease in DO analysis (Figure 4A), namely, BDKRB2, CAMP, COL1A1, F2RL1, F3, MS4A2, CXCR3, ICAM1, IGFBP3, IGHE, IL1A, IL1B, IL1RN, IL6, CXCL8, IL9R, IL10, IL18, CXCL10, KRT18, LAMA5, LAMC2, LEP, MET, CXCL9, MMP1, MMP2, MMP9, PLAUR, PPARG, RNASE2, RNASE3, SOD2, TLR4, and IL1RL1. The gene discussed is MMP9; the disease is dermatomyositis.