1. Department of Respiratory Medicine; Bispebjerg Hospital; Copenhagen Denmark
2. Department of Epidemiology Research; Statens Serum Institut; Copenhagen Denmark
3. Institute of Regional Health Services Research & Odense Patient Data Explorative Network; University of Southern Denmark; Odense Denmark
4. The Danish Twin Registry; University of Southern Denmark; Odense Denmark
5. Copenhagen Prospective Studies of Asthma in Childhood (COPSAC); Danish Pediatric Asthma Center; Gentofte Hospital; Copenhagen Denmark
6. Department of Dermato-allergology; Gentofte Hospital; Copenhagen Denmark