In particular one of five tested SNPs spanning Transforming Growth Factor β1 TGFB1 (at 41.8 Mbp) was associated with severe COPD in case (n = 304) control (n = 441) analyses and airway obstruction in family (77 pedigrees) analyses (p < 0.05) [10]. Here, TGFB1 is linked to Airway obstruction.