Another study has shown that serum biomarkers of pulmonary fibrosis, including type IV collagen (COL4), laminin (LN), hyaluronic acid (HA), and procollagen III N-terminal peptide (PIIINP), were elevated in PC19-PF patients and may serve as indicators of PC19-PF severity [69]. The gene discussed is LAMB2; the disease is pemphigus foliaceus.