Figure 1.

Genome-wide association study design for subjects with chronic obstructive pulmonary disease (COPD) with a ratio of pulmonary artery (PA) diameter to aorta (A) diameter greater than 1. GOLD (Global Initiative for Chronic Obstructive Lung Disease) 2–4 was defined as having a post-bronchodilator forced expiratory volume at 1 second (FEV₁)/forced vital capacity (FVC) less than 0.7 and FEV₁ less than 80% predicted. Normal spirometry was defined as a post-bronchodilator FEV₁/FVC of 0.7 or greater and an FEV₁ of 80% predicted or greater. PAE, PA enlargement.