1. King's College London School of Medicine, Division of Gene and Cell Based Therapy, London, United Kingdom;
2. King's College Hospital, Department of Haematological Medicine, London, United Kingdom;
3. King's College London School of Medicine, Division of Genetics and Molecular Medicine, London, United Kingdom;
4. Centre National de Génotypage, Institut Génomique, Commissariat à l'Energie Atomique, Evry, France;
5. Wellcome Trust Centre for Human Genetics, Oxford, United Kingdom