In human study, the patients with AE-IPF had higher serum PRDX4 protein levels than those with S-IPF, and serum PRDX4 protein levels showed higher prognostic value than both serum KL-6 and SP-D levels for distinguishing AE-IPF from S-IPF. The gene discussed is SFTPD; the disease is idiopathic pulmonary fibrosis.