TGFB1 and Airway obstruction: The study by van Diemen et al. [36], found that the TGF-β1 polymorphisms were associated with forced expiratory volume in 1 s (FEV1)/inspiratory vital capacity (IVC) in patients with COPD, suggesting that the severity of airway obstruction was genetically influenced by the TGF-β1 polymorphisms.