1. Molecular Haematology Laboratory and INSERM Unit U432,
2. Paediatric Haematology Unit, Hôpital Saint Louis,
3. Haematology Laboratory and INSERM Unit U417,
4. Onco‐Haematology Unit,
5. Armand‐Trousseau Hospital Immuno‐Haematology Unit,
6. Haematology Laboratory, Hôpital Necker, Paris, France