Up to now, extensive genome-wide linkage scanning has identified a single nucleotide polymorphism (SNP) in the promoter region of the MUC5B gene (rs35705950) that is the principal risk factor (genetic and otherwise) for developing IPF, accounting for 30–35% of the risk [4, 12–19]. This evidence concerns the gene MUC5B and idiopathic pulmonary fibrosis.