MUC5B and idiopathic pulmonary fibrosis: The association of the MUC5B promoter polymorphism with IPF has been replicated and confirmed in nine independent cohorts (10, 11, 49, 50, 70–74), including in a 2013 GWAS (OR for T minor allele = 4.51; 95% CI = 3.91–5.21; P = 7.21 × 10−95) (10).