HSP47-reactive IgG titers of patients with idiopathic NSIP (median, 0.281 [range, 0.194–0.734]) were significantly higher than those of idiopathic UIP (0.165 [0.059–0.361]) (P < 0.01), COP (0.137 [0.101–0.394]) (P < 0.05), and healthy volunteers (0.181 [0.062–0.349]) (P < 0.05) (Fig. 1). This evidence concerns the gene SERPINH1 and idiopathic pulmonary fibrosis.