COPDGene is a multicenter observational sample primarily focused on identifying genetic risk factors for COPD, as previously described.16 Recruited participants were non-Hispanic white or African American and aged 45 to 80 years old, who reported a history of smoking (currently or past) and 10 or more cigarette pack-years. FTND was assessed in current smokers only. We used the non-Hispanic white current smoking participants for this study. Among the COPD cases, disease severity was staged according to the Global Initiative for Chronic Obstructive Lung Disease criteria, which are based on post-bronchodilator pulmonary function measures. COPD controls had pulmonary function measures in the normal range for their age and height, separately by sex. Exclusion criteria for acute and chronic respiratory disease, cancer and other conditions were used. COPDGene participants were genotyped on the Illumina HumanOmni1-Quad BeadChip array. After applying our standard QC procedures (Supplementary Information), there were 2211 COPDGene participants for analysis.
