The pathogenesis of PF has many mechanisms, including alveolar epithelial cell inefficacy, endothelial cell disorders, fibroblast heterogeneity and plasticity, immune cell regulation, integrin-mediated activation of the TGF-β pathway, cytokine regulation, and, in recent years, microbial ecological regulation of the gut-lung axis, which has been found to be a pathogenetic mechanism and a modifying factor of PF disease. The gene discussed is TGFB1; the disease is pemphigus foliaceus.