1. Hematology Unit, Fondazione Istituto di Ricovero e Cura a Carattere Scientifico Ca’ Granda Ospedale Maggiore Policlinico, Milan, Italy;
2. Department of Oncology and Hemato-Oncology, University of Milan, Milan, Italy;
3. Centre de Référence Maladies Rares sur les Cytopénies Auto-Immunes de l’Adulte, Centre Hospitalier Universitaire Henri Mondor, Assistance Publique–Hôpitaux de Paris, Créteil Université Paris-Est Créteil, Paris, France;
4. Department of Hematology, Odense University Hospital, Odense, Denmark;
5. Hospital Universitario Principe de Asturias (Alcala de Henares), Madrid, Spain;
6. Institute of Hematology “L. e A. Seragnoli”, University of Bologna, Bologna, Italy;
7. Ematologia, Spedali Civili di Brescia, Brescia, Italy;
8. Department of Translational Medicine, Azienda Ospedaliera-Universitaria “Maggiore della Carità”, University of Eastern Piedmont, Novara, Italy;
9. Dipartimento di Ematologia e Oncologia, Niguarda Cancer Center, Azienda Socio Sanitaria Territoriale Ospedale Niguarda, Milan, Italy;
10. Servicio de Hematología, Hospital Universitario Virgen del Rocio, Seville, Spain;
11. Clinical Haematology, Barts Health National Health Service Trust, Queen Mary University, London, United Kingdom;
12. Epidemiology Unit, Fondazione Istituto di Ricovero e Cura a Carattere Scientifico Ca’ Granda Ospedale Maggiore Policlinico, Milan, Italy;
13. Amsterdam University Medical Center, University of Amsterdam–Sanquin Landsteiner Laboratory, Amsterdam, The Netherlands;
14. Department of Hematology, Rigshospitalet, Copenhagen, Denmark; and
15. Servicio de Hematología, Hospital Universitario de Burgos, Burgos, Spain