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C. Inserm and A. M. , The sequencing costs for ChIP-seq experiments were partially granted by an ESGI consortium grant from the Seventh Framework Programme (FP7/2007-2013) under grant agreement no. 262055. E.D. gratefully acknowledges support from the Association pour la Recherche sur le Cancer and the Fondation pour la Recherche Médicale. We thank participants in the GRAALL-2003 and -2005 study groups for collecting and providing biological samples and data sets. The GRAALL was supported by grants P0200701 and P030425/ AOM03081 from the Programme Hospitalier de Recherche Clinique, Ministère de l'Emploi et de la Solidarité, France and the Swiss Federal Government in Switzerland. Samples were collected and processed by the AP-HP 'Direction de Recherche Clinique' Tumour Bank at Necker-Enfants Malades. We are grateful to V. Lheritier for her help in collecting clinical samples, is a recipient of a fellowship from INCa (#ASC12035ASA). B.N. is the recipient of a CHRT INSERM/Assistance Publique-Hôpitaux de Marseille (HP-HM)

L. C. , R. F. , M. A. , M. G. , I. G. et al., with the advice of C.G. and B.M.; episomal reintegration characterization was performed by