The G/T rs35705950 SNP found in the promoter of mucin 5B (MUC5B) on chromosome 11p15.5 [18,19] has one of the highest (~40%) [20] and most reproducible associations with idiopathic pulmonary fibrosis (IPF) across white, hispanic, and Asian populations [21,22,23,24,25,26,27,28,29,30,31,32,33,34,35,36,37], with homozygous mutants exhibiting a higher risk of developing the disease [38] and higher mortality [39]. Here, MUC5B is linked to idiopathic pulmonary fibrosis.