Interestingly, by studying the functional annotations of the two lists of switch genes from the COPD training and test set, we found that they share COPD-related KEGG pathways (Table 1) and GO biological processes (Table 2), namely the NF-κB and toll-like receptor signaling pathways, regulation of immune and inflammatory response and key processes in cell development. Here, NFKB1 is linked to chronic obstructive pulmonary disease.