KL-6, SP-D, and chemokine ligand 18 (CCL18) have a high sensitivity but are not specific in diagnosing SSc-ILD, and CCL18 can predict the deterioration of IPF and SSc-ILD where CCL18 has a higher predictive value (194–208). The gene discussed is SFTPD; the disease is idiopathic pulmonary fibrosis.