LTBP4 and chronic obstructive pulmonary disease: Genetic variants near TGF-β superfamily members TGFB2 (Castaldi et al., 2014; Cho et al., 2014), ACVR1B (Boueiz et al., 2019), LTBP4 (Wain et al., 2017), and BMP6 (Loth et al., 2014) have been identified in GWAS for lung function and COPD, but prior to this study the region near ACVR1B was the only one linked to a gene in the TGF-β pathway through functional studies (Boueiz et al., 2019).