The Genetic Epidemiology of COPD Study (COPDGene) enrolled COPD cases and control smokers at 21 clinical centers throughout the United States [25]. Subjects are 45–80 years old and have a smoking history of at least 10 pack-years. This analysis included the first 994 non-Hispanic white case and control subjects enrolled in COPDGene (Table 1). In these samples, a set of 75 ancestry informative markers has been previously genotyped and did not show evidence of population stratification [11].
