Corresponding author: m.cavazzana@nck.aphp.fr, Professor Marina Cavazzana-Calvo, Biotherapy Department, Hopital Necker EnfantsMalades, 149 rue de Sevres, F-75015 Paris, France; tel. +33 1 44 49 50 68; fax +33 1 44 49 25 05. 18 These authors contributed equally to this work 19 These authors contributed equally to this work Author contributions: C.L.-P. and E.M.S contributed equally to this study by performing most of the experimental work and analysis, with the assistance of C.D.-C. and E.M. C.Picard and F.R.-L. performed apoptotic tests on the fibroblasts, gave critical advices and comments in designing the experiments. Experiments shown in Fig. 4 were performed by V.M. A.D. performed the RNA interference experiments. F.V. provided expertise in histological examination. K.L.S.-S. mapped P6 deletion and found P7 mutation. J.C.M. performed the sequencing project. C.B. performed the genome-wide linkage scan. C.Picard, L.M.N., N.M.W., A.F., M.M.A. and M.C.-C. recruited and diagnosed the RD patients and provide materials for them. F.Calvo gave critical comments in designing the experiments and helped to sequence the healthy and pathological samples. C.Petit contributed to the design of the inner ear experiments, F.Candotti designed and coordinated the sequencing project. C. Picard and L.A. performed the Lodscore analysis. L.A. and A.F. contributed equally to this study. M.C.-C. supervised the overall project. M.C.-C., C.L.-P., E.M.S L.A. and A.F. wrote the paper and added the comments from all authors. Author information: All authors declare that there is no competing financial interests. Reprints and permissions information is available at npg.nature.com/reprintsandpermissions. Correspondence and requests for materials should be addressed to Marina Cavazzana-Calvo (m.cavazzana@nck.aphp.fr). NIH Public Access Author ManuscriptNat Genet. Author manuscript; available in PMC 2010 January 1. Published in final edited form as:Nat Genet. We have identified biallelic mutations in the adenylate kinase 2 (AK2) gene in seven patients affected with RD. These mutations resulted in the absence or a strong decrease in protein expression. We then demonstrated that restoration of AK2 expression in the bone marrow cells of RD patients overcomes the neutrophil differentiation arrest underlining its specific requirement in the development of a restricted set of haematopoietic lineages. Lastly, we established that AK2 is specifically expressed in the stria vascularis region of the inner ear, which provides an explanation to the sensorineural deafness. These results suggest a novel mechanism regulating haematopoetic cell differentiation, and involved in one of the most severe human immunodeficiency syndromes.The term "reticular dysgenesis" (RD), was coined in 1959 by de Vall and Seyneheve 1 and relates to the histological findings in primary and secondary lymphohaematopoietic organs, where the scarcity of cells highlights the prominent reticular tissue framework. The lack of polymorphonuclear neutrophils (PMNs) in affected patien...

Patients with mutations in the Artemis gene display a complete absence of T- and B lymphocytes, together with increased cellular radiosensitivity; this leads to a radiosensitive severe combined immunodeficiency (RS-SCID). Allogenic hematopoietic stem-cell (HSC) transplantation is only partially successful in the absence of an human leukocyte antigen-genoidentical donor, and this has prompted a search for alternative therapeutic approaches such as gene therapy. In this study, a self-inactivated lentiviral vector expressing Artemis was used to complement the Artemis knockout mouse (Art(-/-)). Transplantation of Artemis-transduced HSCs into irradiated Art(-/-) mice restored a stable (over a 15-month period of follow-up) and functional T- and cell repertoire that was comparable to that of control mice. The success of secondary transplantations demonstrated that the HSCs had been transduced. One of thirteen mice developed a thymoma 6 months after gene therapy. Although thymic cells were seen to be carrying two lentiviral integration sites, there was no evidence of lentivirus-driven oncogene activation. The Art(-/-) mice were found to be prone to develop T-cell lymphomas, either spontaneously or after irradiation. These data indicate that the observed lymphoproliferation was probably the consequence of the chromosomal instability associated with the Artemis-deficient background. As a whole, our work provides a basis for supporting the gene therapy approach in Artemis-deficient SCID.