TNFRSF9 and idiopathic pulmonary fibrosis: The reasons that the ILA score [all transcripts] performed worse than the ILA score [IPF transcripts] are likely similar to the reasons we did not observe genes differentially expressed with ILA; the reason for the lack of differential gene expression for ILA is multifactorial and is attributable to a combination of limited statistical power, phenotypic heterogeneity of ILA in smokers, and poor reflection of ILA disease processes in peripheral blood gene expression.