Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0021051 (immunodeficiency)
 71,517 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We have previously described the identification of Artemis, a factor involved in the nonhomologous end joining (NHEJ) phase of V(D)J recombination of T and B cell receptor genes. Null mutations of the Artemis gene result in a complete absence of T and B lymphocytes that is associated with increased cell radiosensitivity, causing the radiosensitive T(-)B(-) SCID (RS-SCID) condition. We presently report the occurrence of hypomorphic mutations of the Artemis gene in four patients from two kindreds. Partially preserved in vivo activity of Artemis is associated with the presence of polyclonal T and B lymphocyte populations, albeit in reduced numbers, along with chromosomal instability and development of EBV-associated lymphoma in two of four patients. This syndrome emphasizes the role of Artemis in the NHEJ pathway of DNA repair and suggests that other, yet ill-defined, conditions associating immunodeficiency and lymphoma could be caused by mutations in genes encoding NHEJ factors.
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PMID:Partial T and B lymphocyte immunodeficiency and predisposition to lymphoma in patients with hypomorphic mutations in Artemis. 1256 64

V(D)J recombination constitutes a critical checkpoint in the development of the immune system as shown in several animal models as well as severe combined immune deficiency (SCID) condition in humans. We recently cloned the Artemis gene, whose mutations are responsible for RS-SCID, a condition characterized by an absence of both B and T lymphocytes and associated with increased sensitivity to ionizing radiations. Artemis is ubiquitously expressed and is localized in the nucleus. Artemis belongs to the metallo-beta-lactamase superfamily and defines a new group, beta-CASP, within this family. beta-CASP proteins are beta-lactamases acting on nucleic acids. While RS-SCID patients harbor Artemis loss-of-function mutations, we identified four patients with a combined immunodeficiency characterized by a low but detectable number of both B and T lymphocytes caused by hypomorphic mutations in the Artemis gene. Two of these patients developed aggressive B cell lymphomas, a condition that suggests Artemis may be considered a "caretaker" factor, similarly to the other V(D)J recombination/DNA repair actors.
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PMID:The V(D)J recombination/DNA repair factor artemis belongs to the metallo-beta-lactamase family and constitutes a critical developmental checkpoint of the lymphoid system. 1272 34

Null mutations in Artemis confer a condition described as RS-SCID, in which patients display radiosensitivity combined with severe combined immunodeficiency. Here, we characterize the defect in Artemis in a patient who displayed progressive combined immunodeficiency (CID) and elevated lymphocyte apoptosis. The patient is a compound heterozygote with novel mutations in both alleles, resulting in Artemis proteins with either L70 deletion or G126D substitution. Both mutational changes impact upon Artemis function and a fibroblast cell line derived from the patient (F96-224) has greatly reduced Artemis protein. In contrast to Artemis null cell lines, which fail to repair a subset of DNA double strand breaks (DSBs) induced by ionizing radiation, F96-224 cells show slow but residual DSB rejoining. Despite showing intermediate cellular and clinical features, F96-224 cells are as radiosensitive as Artemis null cell lines. We developed a FACS-based assay to examine cell division and cellular characteristics for 10 days following exposure to ionizing radiation (2 and 4 Gy). This analysis demonstrated that F96-224 cells show delayed cell death when compared with rapid growth arrest of an Artemis null cell line, and the emergence of a cycling population shown by a control line. F96-224 cells also display elevated chromosome aberrations when compared with control cells. F96-224 therefore represents a novel phenotype for a hypomorphic cell line. We suggest that delayed cell death contributes to the progressive CID phenotype of the Artemis patient.
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PMID:Radiation-induced delayed cell death in a hypomorphic Artemis cell line. 1654 May 17

Artemis gene mutations are responsible for the development of a severe combined immunodeficiency [radiation-sensitive (RS) SCID] characterized by a severe B and T cell deficiency and a normal natural killer cell population. To establish the feasibility of a gene therapy approach to the treatment of RS-SCID, we generated a series of lentiviral vectors expressing human Artemis from different promoters and used them to transduce highly purified hematopoietic stem cells (HSCs) from Artemis knockout mice. HSCs transduced by the different viruses were transplanted into either lethally irradiated Rag-1-deficient animals or Artemis knockout mice treated with a nonmyeloablative dose of Busulfan. In both models, transplantation of HSCs transduced by a vector that used a murine phosphoglycerate kinase (PGK) promoter led to a complete functional correction of the immunodeficiency. Corrected animals displayed rescue of mature B cells with normal levels of serum immunoglobulins, together with complete rescue of the T cell compartment as evidenced by the presence of mature T lymphocytes in peripheral blood as well as normal values of thymocytes in thymus. Those B and T cells were capable of activation, as shown both by in vitro stimulation responses and in vivo after immune challenge. Overall, the results indicate that a gene therapy approach for RS-SCID involving the transplantation of genetically modified HSCs is indeed feasible. Furthermore, our studies suggest the possibility that nonmyeloablative conditioning regimens might be effectively used to promote engraftment of genetically modified cells in the case of diseases where standard irradiation-based myeloablative bone marrow transplantation protocols may prove problematic.
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PMID:Complete correction of murine Artemis immunodeficiency by lentiviral vector-mediated gene transfer. 1706 50

Omenn syndrome (OS) is a rare disorder within the combined immunodeficiency family that is characterized by a diffuse exudative, erythematous rash, lymphadenopathy, hepatosplenomegaly, alopecia, and failure to thrive. Specific lab findings unique to OS include hypereosinophilia, elevated IgE, excess production of oligoclonal T-cells and near-to-absent B-cells. Much remains elucidated about the underlying genetic cause of OS. Until recently, it was felt that the disease was primarily caused by mutations of the RAG1 or RAG2 genes. The type of mutation of the RAG1 and RAG2 genes in patients with OS affects the degree of functioning variable (diversity) joining [V(D)J] recombination activity, which is critical to the development of lymphoid cell receptor diversity. New work has also shown that thymic tissue in OS patients demonstrates a severe defect in the expression of the autoimmune regulator element. This may contribute to the development of autoreactive T-cells that are felt to be the causative agent of a number of the clinical hallmarks unique to OS. The genetic spectrum of OS was further expanded when a patient with clinical and immunologic features consistent with OS, without RAG mutation, was found to have mutations in both alleles coding for ARTEMIS, a key V(D)J recombination/DNA repair factor. Regardless of the underlying cause, early recognition is critical because patients die at a very young age without bone marrow transplantation. We describe an infant diagnosed with OS post-mortem in which death was directly related to the development of necrotizing enterocolitis.
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PMID:Necrotizing enterocolitis in an infant with Omenn syndrome. 1717 92

Omenn syndrome is a form of severe combined immunodeficiency associated with erythrodermia, hepatosplenomegaly, lymphadenopathy, and alopecia. Inherited hypomorphic mutations in the recombination activating genes 1 and 2 (RAG1 and RAG2) and in ARTEMIS genes and more recently defects in IL7RA, and RMRP genes have been described to be responsible of this peculiar immunodeficiency. The authors report here a Moroccan patient of four-months-old with classical features of Omenn syndrome, carrying a deletion at the N terminal part of RAG1. Early recognition of this condition is important for genetic counseling and early treatment.
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PMID:Omenn syndrome with mutation in RAG1 gene. 1901 8

Artemis is required for V(D)J recombination and the repair of a subset of radiation-induced DNA double strand breaks (DSBs). Artemis-null patients display radiosensitivity (RS) and severe combined immunodeficiency (SCID), classified as RS-SCID. Strongly impacting hypomorphic Artemis mutations confer marked infant immunodeficiency and a predisposition for EBV-associated lymphomas. Here, we provide evidence that a polymorphic Artemis variant (c.512C > G: p.171P > R), which has a world-wide prevalence of 15%, is functionally impacting. The c.512C > G mutation causes an approximately 3-fold decrease in Artemis endonuclease activity in vitro. Cells derived from a patient who expressed a single Artemis allele with the polymorphic mutational change, showed radiosensitivity and a DSB repair defect in G2 phase, with Artemis cDNA expression rescuing both phenotypes. The c.512C > G change has an additive impact on Artemis function when combined with a novel C-terminal truncating mutation (p.436C > X), which also partially inactivates Artemis activity. Collectively, our findings provide strong evidence that monoallelic expression of the c.512C > G variant impairs Artemis function causing significant radiosensitivity and a G2 phase DSB repair defect. The patient exhibiting monoallelic c.512C > G-Artemis expression showed immunodeficiency only in adulthood, developed bilateral carcinoma of the nipple and myelodysplasia raising the possibility that modestly decreased Artemis function can impact clinically.
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PMID:An Artemis polymorphic variant reduces Artemis activity and confers cellular radiosensitivity. 2103 Mar 22

Primary immunodeficiencies are genetic disorders in which components of immunological pathways are either missing or dysregulated. With the advent of next-generation sequencing, testing for genes in conditions with a heterogeneous genetic background seems more promising. We designed a custom microarray with 385K probe capacity to capture exons of 395 human genes, known or predicted to be associated with primary immunodeficiency and immune regulation. Enriched target DNA was sequenced using a GS FLX Titanium 454 platform. The patients selected were likely to have an underlying immunodeficiency. In one patient with hepatosplenomegaly, recurrent infections and an elevated IgM level, sequence analysis of the patient and his two unaffected parents identified ATM (ataxia telangiectasia mutated) as the underlying defect. In a second child with a clinical SCID phenotype, we detected a mutation in the ARTEMIS gene after focusing on SCID-associated genes. 454 sequencing yielded 152,000-397,000 high-quality reads per patient. 78-99% of the targeted nucleotides were covered at least one time, 76-82% at least five times. Array-based sequence capture expands our capacities to sequence large targeted DNA regions in a less laborious and time-consuming approach. Our array was capable to find the underlying genetic defect in two patients with suspected primary immunodeficiency. Upcoming whole-exome sequencing definitely will add more valuable data, but bioinformatical analysis and validation of variants already pose major challenges.
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PMID:Array-based sequence capture and next-generation sequencing for the identification of primary immunodeficiencies. 2201 23

DNA non-homologous end-joining (NHEJ) is the major DNA double strand break (DSB) repair pathway in mammalian cells. Defects in NHEJ proteins confer marked radiosensitivity in cell lines and mice models, since radiation potently induces DSBs. The process of V(D)J recombination functions during the development of the immune response, and involves the introduction and rejoining of programmed DSBs to generate an array of diverse T and B cells. NHEJ rejoins these programmed DSBs. Consequently, NHEJ deficiency confers (severe) combined immunodeficiency - (S)CID - due to a failure to carry out V(D)J recombination efficiently. NHEJ also functions in class switch recombination, another step enhancing T and B cell diversity. Prompted by these findings, a search for radiosensitivity amongst (S)CID patients revealed a radiosensitive sub-class, defined as RS-SCID. Mutations in NHEJ genes, defining human syndromes deficient in DNA ligase IV (LIG4 Syndrome), XLF-Cernunnos, Artemis or DNA-PKcs, have been identified in such patients. Mutations in XRCC4 or Ku70,80 in patients have not been identified. RS-SCID patients frequently display additional characteristics including microcephaly, dysmorphic facial features and growth delay. Here, we overview the clinical spectrum of RS-SCID patients and discuss our current understanding of the underlying biology.
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PMID:The clinical impact of deficiency in DNA non-homologous end-joining. 2478 May 57

DNA non-homologous end-joining (NHEJ) is the major DNA double strand break (DSB) repair pathway in mammalian cells. Defects in NHEJ proteins confer marked radiosensitivity in cell lines and mice models, since radiation potently induces DSBs. The process of V(D)J recombination functions during the development of the immune response, and involves the introduction and rejoining of programmed DSBs to generate an array of diverse T and B cells. NHEJ rejoins these programmed DSBs. Consequently, NHEJ deficiency confers (severe) combined immunodeficiency - (S)CID - due to a failure to carry out V(D)J recombination efficiently. NHEJ also functions in class switch recombination, another step enhancing T and B cell diversity. Prompted by these findings, a search for radiosensitivity amongst (S)CID patients revealed a radiosensitive sub-class, defined as RS-SCID. Mutations in NHEJ genes, defining human syndromes deficient in DNA ligase IV (LIG4 Syndrome), XLF-Cernunnos, Artemis or DNA-PKcs, have been identified in such patients. Mutations in XRCC4 or Ku70,80 in patients have not been identified. RS-SCID patients frequently display additional characteristics including microcephaly, dysmorphic facial features and growth delay. Here, we overview the clinical spectrum of RS-SCID patients and discuss our current understanding of the underlying biology.
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PMID:Reprint of "The clinical impact of deficiency in DNA non-homologous end-joining". 2462 83


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