1. Department of Public Health Laboratory of Clinical Epidemiology ‐ IRCCS Istituto di Ricerche Farmacologiche “Mario Negri” Milan Italy
2. Department of Clinical Sciences and Community Health Università degli Studi di Milano Milan Italy
3. Department of Dermatology, Azienda Ospedaliera Papa Giovanni XXIII Centro Studi GISED Bergamo Italy
4. Université Paris Descartes Paris France
5. INSERM Institut Necker‐Enfants Malades Paris France
6. CNRS UMR 8253 Institut Necker‐Enfants Malades Paris France