AP2A2 and chronic obstructive pulmonary disease: Our GWAS meta-analysis of three studies of COPD subjects with CB relative to smoking controls not only reconfirmed previously known genome-wide significant SNPs in FAM13A related to lung function [32,33] and COPD [21-23], but also revealed a novel locus on 11p15.5, including EFCAB4A, CHID1, and AP2A2. Proteins encoded by one or more of these three genes could be involved in CB.