We identified a series of significant pathways, including BCR signaling pathway, ECM-related pathways, NF-κB and TGF-β signaling pathways, and several hub genes (i.e. CD19, BLK, MS4A1, POU2AF1, and COL6A1) that may be involved in the emphysema phenotype of COPD. This evidence concerns the gene BLK and chronic obstructive pulmonary disease.