Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:Q00604 (X-linked)
 16,883 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Human severe combined immunodeficiency (SCID), a syndrome of profoundly impaired cellular and humoral immunity, is most commonly caused by mutations in the X-linked gene for interleukin-2 (IL-2) receptor gamma chain (IL2RG). For mutational analysis of IL2RG in males with SCID, SSCP screening was followed by DNA sequencing. Of 40 IL2RG mutations found in unrelated SCID patients, 6 were point mutations at the CpG dinucleotide at cDNA 690-691, encoding amino acid R226. This residue lies in the extracellular domain of the protein in a region not previously recognized to be significantly conserved in the cytokine receptor gene family, 11 amino acids upstream from the highly conserved WSXWS motif. Three additional instances of mutation at another CpG dinucleotide at cDNA 879 produced a premature termination signal in the intracellular domain of IL2RG, resulting in loss of the SH2-homologous intracellular domain known to be essential for signaling from the IL-2 receptor complex. Mutations at these two hotspots constitute > 20% of the X-linked SCID mutations found by our group and a similar proportion of all reported IL2RG mutations.
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PMID:Two mutational hotspots in the interleukin-2 receptor gamma chain gene causing human X-linked severe combined immunodeficiency. 766 84

The IL2RG gene encoding the gamma chain of the lymphocyte receptor for IL-2 lies in human Xq13.1 and is mutated in males with X-linked severe combined immunodeficiency (SCID). In a large Canadian pedigree genetic linkage studies demonstrated that the proband's grandmother was the source of an X-linked SCID mutation. However, her T cells did not show the expected skewed X chromosome inactivation pattern of female carriers of SCID, despite her having one affected son and two carrier daughters with skewed X inactivation. Single strand conformation polymorphism analysis of IL2RG in the affected proband was abnormal in exon 5; sequencing revealed a nine nucleotide in-frame duplication insertion. The three duplicated amino acids included the first tryptophan of the "WSXWS" motif found in all members of the cytokine receptor gene superfamily. Mutation detection in the pedigree confirmed that the founder grandmother's somatic cells had only normal IL2RG, and further showed that the SCID-associated X chromosome haplotype was inherited by three daughters, one with a wild type IL2RG gene and two others with the insertional mutation. Female germ line mosaicism is unusual, but its presence in this X-linked SCID family emphasizes the limitations of genetic diagnosis by linkage as compared with direct mutation analysis.
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PMID:Female germ line mosaicism as the origin of a unique IL-2 receptor gamma-chain mutation causing X-linked severe combined immunodeficiency. 786 Jul 24

The gene encoding the gamma chain of the lymphocyte interleukin-2 receptor has been cloned and shown to be required to associate with the beta chain in order for IL-2 internalization and cell activation to occur (1). We considered this gene, IL2RG, a candidate for the X-linked form of severe combined immunodeficiency at the SCIDX1 locus, in which affected males have impaired lymphocyte development. Using fluorescence in situ hybridization and PCR amplification of somatic cell hybrid DNAs, we mapped IL2RG to human Xq13.1, a location within the SCIDX1 critical region established by linkage analysis. The 4.2 kb IL2RG gene was sequenced, and its genomic organization was elucidated. Seven of 19 transformed B-lymphocyte cell lines with independent SCIDX1 mutations had absent or minimal IL2RG mRNA. Unique point mutations were documented to be specifically associated with the disease and the carrier state in four unrelated affected males and their family members: one in a boy with no detectable IL2RG mRNA, in which the mutation ablated a splice donor site; one causing premature chain termination; and two causing distinct amino acid changes. The demonstration of impaired IL2RG mRNA expression in males with X-linked SCID and of unique point mutations in SCIDX1 pedigrees constitutes powerful evidence that the SCIDX1 gene is IL2RG. Noguchi et al. (2) have independently published IL2RG mapping to Xq13 and discovery of mutations in three affected males. The specific pathogenesis of IL2RG mutations and approaches to gene therapy can now be addressed in the X-linked form of SCID.
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PMID:The interleukin-2 receptor gamma chain maps to Xq13.1 and is mutated in X-linked severe combined immunodeficiency, SCIDX1. 840 90

X-linked severe combined immunodeficiency disease (SCID) results from mutations of IL2RG, the gene encoding the interleukin-2 receptor gamma chain, also known as the common gamma chain (gamma c). A distinct form of autosomal recessive SCID occurs at an increased frequency among the Navajo Native American population. The disease gene responsible for autosomal Navajo SCID remains to be determined. We report the occurrence of X-linked SCID in a Navajo Native American kindred with two affected brothers. X-linked SCID was suggested by the presence of circulating B cells and the absence of surface gamma c expression in a cell line derived from an affected male. A C-to-T transition was demonstrated in exon 5 of the IL2RG gene, resulting in the substitution of tryptophan for arginine at position 224. This change was not present in the peripheral blood lymphocytes of the mother, thus proving the occurrence of a new mutation in the maternal germline. This report underscores the importance of establishing a specific genetic diagnosis for SCID cases and illustrates the inherent difficulties in providing genetic counseling in cases involving mosaicism.
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PMID:Maternal mosaicism for a novel interleukin-2 receptor gamma-chain mutation causing X-linked severe combined immunodeficiency in a Navajo kindred. 904 83

Severe combined immunodeficiency (SCID) is a syndrome of profoundly impaired cellular and humoral immunity. In humans, SCID is most commonly caused by mutations in the X-linked gene IL2RG, which encodes the common gamma chain, gamma c, of the leukocyte receptors for interleukin-2 and multiple other cytokines. To investigate the frequency and variety of IL2RG mutations that cause SCID, we analyzed DNA, RNA, and B-cell lines from a total of 103 unrelated SCID-affected males and their relatives using a combination of molecular and immunologic techniques. Sixty-two different mutations spanning all eight IL2RG exons were found in 87 cases, making possible correlations between mutation type and functional consequences. Although skewed maternal X chromosome inactivation, single-strand conformation polymorphism, mRNA expression, and cell surface staining with anti-gamma c antibodies were all helpful in establishing IL2RG defects as the cause of SCID, only dideoxy fingerprinting and DNA sequence determination each detected 100% of the IL2RG mutations in our series. Abnormal gamma c chains may be expressed in the lymphocytes of as many as two thirds of patients with X-linked SCID. Specific mutation diagnosis thus remains technically challenging, but it is important for genetic counseling and perhaps for helping to select appropriate subjects for retroviral gene therapy trials, This is a US government work. There are no restrictions on its use.
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PMID:Mutation analysis of IL2RG in human X-linked severe combined immunodeficiency. 905 18

IL2RG, the gene encoding the common gamma chain, gamma c, of the receptor for interleukin-2 and other cytokines, has been identified as the disease gene for severe combined immunodeficiency (SCID) of the X-linked type. Specific mutational diagnosis for X-linked SCID has thus become possible. For many women at risk for carrying an IL2RG mutation, no samples were saved from an affected male relative prior to either death or bone marrow transplantation (BMT). To establish optimal methods for genetic evaluation of such women, we compared mutational screening by single-strand conformational polymorphism, heteroduplex analysis and dideoxy fingerprinting (ddF). Abnormally migrating band patterns were followed up with direct sequencing for identification of specific mutations. The most sensitive method, ddF, detected heterozygous alterations, subsequently confirmed to represent significant mutations, in all of 19 unrelated obligate or suspected carriers studied. Some of these women, as well as others at risk for carrying an X-linked SCID mutation, enrolled in a study of prenatal diagnosis after fetal testing for gender determination. Originally using linkage analysis and, more recently, specific detection of IL2RG mutations, we evaluated pregnancies at risk for X-linked SCID prospectively on a research basis. Of 27 male fetuses tested 14 were predicted to be unaffected and confirmed to have normal immune status at birth. Among pregnancies predicted to be affected, 2 were terminated, while 11 affected males were born at term. Nine of these received neonatal BMT, one had BMT at 3 months of age, and one underwent a successful experimental in utero BMT. In our study cohort accurate prenatal diagnosis assisted decision making and expanded treatment options for families at risk for having infants with a severe, but treatable genetic disorder that presents early in life.
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PMID:Carrier and prenatal diagnosis of X-linked severe combined immunodeficiency: mutation detection methods and utilization. 915 Jul 30

Severe combined immunodeficiency (SCID) is caused by multiple genetic defects. The most common form of SCID, X-linked SCID (XSCID), results from mutations in IL2RG (ref. 4), which encodes the common cytokine receptor gamma chain (gamma(c)) that is shared by the IL-2, IL-4, IL-7, IL-9 and IL-15 receptors. In XSCID and SCID resulting from mutations in JAK3, which encodes a Janus family tyrosine kinase that couples to gamma(c) and is required for gamma(c)-dependent signalling, T- and natural killer (NK)-cells are decreased but B-cell numbers are normal (T(-)B(+)NK(-)SCID). Some SCID patients lack T cells but retain NK cells. Given diminished T-cell development in Il7- or Il7r-deficient mice and that Il/7r-deficient mice have NK cells, we hypothesized that T(-)B(+)NK(+) SCID might result from defective IL-7 signalling, although apparent differences in the role of the IL-7/IL-7R pathway in humans and mice in T-cell and B-cell development have been suggested. We now demonstrate that defective IL7R expression causes T(-)B(+)NK(+) SCID, indicating that the T-cell, but not the NK-cell, defect in XSCID results from inactivation of IL-7Ralpha signalling.
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PMID:Defective IL7R expression in T(-)B(+)NK(+) severe combined immunodeficiency. 984 16

Combined immune deficiencies comprise a spectrum of genetic disorders characterized by developmental or functional defects of both T and B lymphocytes. Recent progress in cell biology and molecular genetics has unraveled the pathophysiology of most of these defects. In particular, the most common form of severe combined immune deficiency in humans, with lack of circulating T cells, a normal or increased number of B lymphocytes, and an X-linked pattern of inheritance (SCIDXI) has been shown to be due to defects of the IL2RG gene, encoding for the common gamma chain (gammac), shared by several cytokine receptors. Furthermore, defects of the JAK3 gene, encoding for an intracellular tyrosine kinase required for signal transduction through gammac-containing cytokine receptors, have been identified in patients with autosomal recessive T-B+ SCID. Characterization of the functional properties of cytokines that signal through the gammac-JAK3 signaling pathway has been favored by the detailed analysis of SCID patients. Specifically, the key role of IL-7 in promoting T cell development has been substantiated by the identification of rare patients with T-B+ SCID who have a defect in the alpha subunit of the IL-7 receptor (IL7Ralpha). The heterogeneity of genetic defects along the same signaling pathway that may lead to combined immune deficiency is paralleled by the heterogeneity of immunological phenotypes that may associate with defects in the same gene, thus creating a need for detailed immunological and molecular investigations in order to dissect the spectrum of combined immune deficiencies in humans.
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PMID:Combined immunodeficiencies due to defects in signal transduction: defects of the gammac-JAK3 signaling pathway as a model. 1099 86

The development of T-cell leukaemia following the otherwise successful treatment of three patients with X-linked severe combined immune deficiency (X-SCID) in gene-therapy trials using haematopoietic stem cells has led to a re-evaluation of this approach. Using a mouse model for gene therapy of X-SCID, we find that the corrective therapeutic gene IL2RG itself can act as a contributor to the genesis of T-cell lymphomas, with one-third of animals being affected. Gene-therapy trials for X-SCID, which have been based on the assumption that IL2RG is minimally oncogenic, may therefore pose some risk to patients.
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PMID:Gene therapy: therapeutic gene causing lymphoma. 1698 60

The gene IL2RG encodes the gamma-chain of the interleukin-2 receptor and is mutated in patients with X-linked severe combined immune deficiency (X-SCID). Woods et al. report the development of thymus tumours in a mouse model of X-SCID after correction by lentiviral overexpression of IL2RG and claim that these were caused by IL2RG itself. Here we find that retroviral overexpression of IL2RG in human CD34+ cells has no effect on T-cell development, whereas overexpression of the T-cell acute lymphoblastic leukaemia (T-ALL) oncogene LMO2 leads to severe abnormalities. Retroviral expression of IL2RG may therefore not be directly oncogenic--rather, the restoration of normal signalling by the interleukin-7 receptor to X-SCID precursor cells allows progression of T-cell development to stages that are permissive for the pro-leukaemic effects of ectopic LMO2.
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PMID:Gene therapy: is IL2RG oncogenic in T-cell development? 1664 81


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