Subjects from a case-control study [21],[22] recruited from Bergen, Norway were used as the discovery cohort in the GWAS. Baseline characteristics of the subjects are shown in Table 1. The entry criteria for COPD cases were post-bronchodilator forced expiratory volume in 1 second (FEV1) <80% predicted and FEV1/FVC (forced vital capacity) <0.7. The controls were selected based on post-bronchodilator FEV1 >80% predicted and FEV1/FVC >0.7. Individuals with Pi ZZ, ZNull, Null-Null or SZ α1-antitrypsin deficiency were excluded. Subjects with chronic pulmonary disorders other than COPD (e.g., lung cancer, sarcoidosis, active tuberculosis, and lung fibrosis) were also excluded. Because of the potential overlap in susceptibility genes for COPD and asthma, and the difficulty of diagnosing COPD vs. asthma in smokers with chronic airflow obstruction, previous asthma diagnosis was not used as an exclusion criterion. Both cases and controls were required to have a minimum of 2.5 pack-years of smoking. A total of 823 COPD cases and 810 controls were included in the present analysis. All of the subjects used in the primary and replication populations were current or former smokers (Table
