The optimal cut-off value for MMP-7 and MMP-10 that achieved the best sensitivity and specificity were < 35,114 pg/mL and < 567.0 pg/mL, respectively, for characterizing RA-ILD+versus IPF, and < 33,983 pg/mL and < 1007 g/mL for identifying SSc-ILD+versus IPF (Additional File 2: Table S2). The gene discussed is MMP7; the disease is idiopathic pulmonary fibrosis.