1. Department of Haematology, Imperial College School of Medicine, Hammersmith Hospital, London, U.K.,
2. Dipartimento di Oncologia Clinica e Sperimentale, Universitá di Genova and Istituto Nazionale per la Ricerca sul Cancro, Genova, Italy,
3. Minesterio da Saude, Hospital Central Especializado de Criancas Maria Pia, Porto, Portugal,
4. Department of Haematology, Royal Free Hospital, London, U.K.,
5. First Paediatric Clinic, University of Thessaloniki, Greece,
6. Department of Human Genetics, Memorial Sloan‐Kettering Cancer Center, New York, U.S.A.