TGFB1 and idiopathic pulmonary fibrosis: Regarding the TGF-β polymorphisms, Xu et al. found no significant difference in the TGF-β genotype distribution between the CPFE group and two other groups, although the difference was noted between IPF and emphysema patients, with the T allele frequency of TGF-β1 in T869C being higher in patients with emphysema than in those with IPF [142].