To assess whether the novel regions that we identified as associated with FEV1 extremes are also associated with COPD, we defined individuals fulfilling spirometric criteria for the Global Initiative for Chronic Obstructive Lung Disease (GOLD) Stage 2+ COPD (FEV1:FVC ratio <0·7 and percent predicted FEV1<80%) as COPD cases and we defined individuals with FEV1:FVC ratio >0·7 and percent predicted FEV1 in excess of 80% from the high FEV1 strata as controls. Post-bronchodilator spirometry was not available, although drug treatment was not withheld before spirometry.
