1 Regional Referral Centre for Rare Lung Diseases, University Hospital "Policlinico", Dept of Clinical and Experimental Medicine, University of Catania, Catania, Italy.
2 Center for Interstitial and Rare Lung Diseases, Pneumology and Respiratory Critical Care Medicine, Thoraxklinik, University of Heidelberg, Heidelberg, Germany.
3 Dept of Medicine, University of California, San Francisco, CA, USA.
4 Dept of Respiratory Medicine, Erasmus University Medical Centre, Rotterdam, The Netherlands.
5 Dept of Epidemiology and Biostatistics, University of California, San Francisco, CA, USA.
6 Regional Referral Centre for Rare Lung Diseases, University Hospital "Policlinico", Dept of Clinical and Experimental Medicine, University of Catania, Catania, Italy vancheri@unict.it.