All SNPs appeared in the 1000 Genomes Project imputation reference panel in exonic GSTCD. In addition a targeted sequencing study in both controls and subjects with COPD that focused on 26 regions known to affect lung function [4,5,9] (see Table S2B) identified two intronic SNPs in GSTCD that do not appear in the 1000 Genomes Project imputation reference panel. Here, GSTCD is linked to chronic obstructive pulmonary disease.