Preclinical PF (PrePF) is frequently reported in smokers and patients with f-IPF 162, and the polymorphism of the MUC5B promoter can be used as an indicator of IPF susceptibility for identifying individuals with PrePF 163 and predicting the radiological progression of PrePF, as well as the prognosis of IPF 164. The gene discussed is MUC5B; the disease is idiopathic interstitial pneumonia.