In 2011, Seibold et al. identified a common variant (rs35705950) in the promoter region of the mucin 5b (MUC5B) gene, which was associated with familial pulmonary fibrosis, sporadic idiopathic pulmonary fibrosis (IPF) and increased expression of mucin 5B in the lung (1). Here, MUC5B is linked to idiopathic pulmonary fibrosis.