MUC5B and idiopathic pulmonary fibrosis: Mucin 5B (MUC5B) played an important role in immune regulation in maintaining bronchoalveolar epithelial function, and its genetic variation had been identified as a risk factor for IPF5,6.So far, Genome-wide Association Study (GWAS) has found a SNP in the promoter region of MUC5B gene (rs35705950), in which the T allele frequency was 30–35% in IPF cases6–14.Variant rs35705950 alone explains 5.9–9.4% of disease liability in the general population and 13.5% in people > 65 years of age15.