title: Omenn syndrome in the context of other B cell-negative severe combined immunodeficiencies.
abstract: Severe combined immunodeficiencies represent a heterogeneous group of hereditary defects of the immune system that affect both T and B cells and whose etiology has only recently begun to be understood. A portion of these SCID patients bear a defect in either of the two recombination-activating genes, Rag-1 or Rag-2, while others have mutations in a newly identified gene, Artemis. Omenn syndrome is an unusual severe immunodeficiency with T cells but no B cells, and peculiar features also due to a defect in Rag-1 or Rag-2 genes. All these three forms are characterized by an impairment of the VDJ recombination, the process that insures the somatic diversification of immunoglobulin and T cell receptor-encoding genes. Recent findings have enabled us to better understand the pathophysiology of these three immunodeficiencies, which affect the V(D)J recombination process to a different extent and in different ways.
authors.affiliation: Department of Human Genome and Multifactorial Disease, Institute of Biomedical Technology, Medical Research Council, Milan, Italy. villa@itba.mi.cbr.it
authors.forename: Anna
authors.initials: A
authors.lastname: Villa
authors.forename: Christina
authors.initials: C
authors.lastname: Sobacchi
authors.forename: Paulo
authors.initials: P
authors.lastname: Vezzoni
mesh_terms: D001402:B-Lymphocytes / Q000276:immunology*; D004268:DNA-Binding Proteins / Q000235:genetics / Q000276:immunology*; D004720:Endonucleases; D016654:Genes, RAG-1 / Q000276:immunology*; D006801:Humans; D009154:Mutation; D009687:Nuclear Proteins; D016511:Severe Combined Immunodeficiency / Q000235:genetics / Q000276:immunology*; D001618:beta-Lactamases / Q000235:genetics*
chemical_list: D004268:DNA-Binding Proteins; D009687:Nuclear Proteins; C499311:RAG2 protein, human; C064655:V(D)J recombination activating protein 2; C426344:DCLRE1C protein, human; D004720:Endonucleases; D001618:beta-Lactamases