Recent genetic evidence reported several polymorphisms in protease (e.g., MMP1 and MMP12), anti-protease (e.g., α1-antitrypsin, α1-antichymotrypsin, and α1-macroglobulin), antioxidant (e.g., heme oxygenase-1), cytokines (e.g., TGFβ1, TNF-α, IL-1 complex, IL-8, and IL-13), and other various genes (e.g., CFTR, human leukocyte antigen, vitamin D-binding protein, and β2 adrenergic receptor) that may be associated with COPD [166]. Here, CFTR is linked to chronic obstructive pulmonary disease.