The ROC curve analysis indicated that SP-D had the highest diagnostic accuracy in distinguishing IPF from control subjects (AUC 0.9089, 95% CI 0.8196–0.9983, p < 0.0001) followed by MMP-7 (AUC 0.8946, 95% CI 0.8011–0.9882, p < 0.0001), and KL-6 (AUC 0.8589, 95% CI 0.7430–0.9749, p < 0.0001). The gene discussed is SFTPD; the disease is idiopathic pulmonary fibrosis.