1. German Center for Lung Research, Dr. von Hauner Children’s Hospital, Ludwig Maximilians University, Munich, Germany
2. Center for Interstitial and Rare Lung Diseases, Department of Pneumology, Ruhrlandklinik University Hospital, Essen, Germany
3. Hôpital Necker-Enfants Malades, Paris, France; and
4. Institute of Clinical Chemistry and Laboratory Medicine, Regensburg University Hospital, Regensburg, Germany