[1] Cardiff Univ, Dept Child Hlth, Sch Med, Cardiff CF14 4XN, S Glam, Wales
[2] Univ Padua, Dept Pediat, Padua, Italy
[3] Univ London Imperial Coll Sci Technol & Med, Dept Paediat, Royal Brompton & Harefield NHS Fdn Trust, London, England
[4] Univ London Imperial Coll Sci Technol & Med, Natl Heart & Lung Div, London, England
[5] Univ Hosp Leuven, Dept Radiol, Louvain, Belgium
[6] Kings Coll Hosp London, Dept Paediat Surg, London, England
[7] Univ Paris 05, Serv Pneumol Pediat, Hop Necker, Paris, France
[8] Univ Hosp Leuven, Dept Obstet & Gynaecol, Louvain, Belgium
[9] Med Univ Graz, Univ Childrens Hosp, Dept Paediat, Graz, Austria
[10] Karolinska Inst, Dept Paediat Surg, Stockholm, Sweden
[11] Kings Coll London, Div Asthma Allergy & Lung Biol, London WC2R 2LS, England
[12] Univ London Imperial Coll Sci Technol & Med, Royal Brompton & Harefield NHS Fdn Trust, Dept Histopathol, London, England
[13] Univ Complutense Madrid, Div Pediat Surg, Hosp U Octubre 12, Madrid, Spain
[14] Univ Roma La Sapienza, Paeditr Dept, Rome, Italy