1. Departments of Haematology, Cytogenetics and CNRS URA 1461, Hôpital Necker Enfants‐Malades and Université Paris V,
2. Hôpital Clémenceau, Caen, and
3. Hôpital Cochin, Paris, France
4. Department of Cytogenetics, Hôpital Hôtel‐Dieu, Paris, and Departments of Haematology,