COPD is characterized by increased levels of inflammatory cytokines, such as interleukins (ILs) IL-1β, IL-4, IL-8, and IL-12 and other proteins, such as chemotactic cytokine (C-C motif ligand, CCL) CCL5, CCL3, macrophage migratory inhibitor factor (MIF), soluble intercellular adhesion molecule (sICAM), granulocyte chemotactic activity (GCA) and surfactant protein D (SP-D), in exhaled breath condensate. This evidence concerns the gene SFTPD and chronic obstructive pulmonary disease.