Subsequently, we conducted an expression analysis of these nine hub genes and found that CCDC71, DOHH, HM13, PDAP1, and SLC25A39 were significantly upregulated in COPD patients, while ACTR6, CAV2, FBXO8, and NEK7 were significantly downregulated in COPD patients (Figure 7B). This evidence concerns the gene PDAP1 and chronic obstructive pulmonary disease.