Moreover, by integrating the BEC RNAseq data with COPD GWAS [98, 99], ENCODE [105], and GTEx [17, 104] databases, we identified ERCC5 SNP rs873601 as a plausible functional connection between ERCC5 DAE (measured at rs17655), and association of rs4150275 with chronic bronchitis in COPD GWAS (Additional file 1: Table S6). Here, ERCC5 is linked to chronic bronchitis.