CHRNA3 and chronic obstructive pulmonary disease: The specific genes involved in COPD are α1-antitrypsin (SERPINA1), serine protease inhibitor-2 (SERPINE2), CHRNA3/5 encoding nicotinic acetylcholine receptor subunits, superoxide dismutase-3 (SOD3), and transforming growth factor-β1 (TGF-β1) [8,9,10,11].