title: CD3 deficiencies.
abstract: OBJECTIVE
  The molecular characterization of inherited T-cell immunodeficiencies has contributed to delineating key factors in human T-cell development. This review reports on the recent description of deleterious mutations in the genes encoding CD3 subunits expressed at the T-lymphocyte membrane in association with the T-cell receptor.
  
  
  RESULTS
  Homozygous mutations in CD3D and CD3E genes lead to a complete block in T-cell development and thus to an early-onset severe combined immunodeficiency phenotype. Thymic studies have shown that the defect in T-cell development occurs at the transition between 'double-negative' and 'double-positive' thymocytes. These results contrast with the partial T-cell immunodeficiency caused by a deficiency in CD3G.
  
  
  CONCLUSIONS
  Two new severe combined immunodeficiency conditions have been reported as a consequence of either CD3D or CD3E deficiency. The distinct phenotype of CD3G deficiency sheds light on the differential roles of CD3 subunits in T-lymphocyte development.
authors.affiliation: Department of Pediatric Immuno-Hematology and Inserm Unit 429, Necker-Enfants Malades Hospital, Paris, France. alain.fischer@nck.ap-hop-paris.fr
authors.forename: Alain
authors.initials: A
authors.lastname: Fischer
authors.forename: Geneviève
authors.initials: G
authors.lastname: de Saint Basile
authors.forename: Françoise
authors.initials: F
authors.lastname: Le Deist
mesh_terms: D017252:CD3 Complex / Q000235:genetics*; D006801:Humans; D038041:Lymphopoiesis; D009154:Mutation; D017260:Receptor-CD3 Complex, Antigen, T-Cell / Q000276:immunology; D016511:Severe Combined Immunodeficiency / Q000276:immunology*; D013601:T-Lymphocytes / Q000276:immunology; D013950:Thymus Gland
chemical_list: D017252:CD3 Complex; D017260:Receptor-CD3 Complex, Antigen, T-Cell