1. Department of Pulmonary Diseases,
2. Groningen Research Institute for Asthma and COPD, University Medical Center Groningen, University of Groningen, Groningen, the Netherlands;
3. Respiratory Bioinformatics and Molecular Biology, University of Technology Sydney, Sydney, Australia;
4. Thirona, Nijmegen, the Netherlands; and
5. COPD Centre, Institute of Medicine, and
6. Department of Respiratory Medicine and Allergology, Sahlgrenska University Hospital, University of Gothenburg, Gothenburg, Sweden