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Query: UMLS:C0004135 (ATM)
 13,001 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The polymerase chain reaction (PCR) was used on DNA obtained from various normal lymphoid tissues to amplify chimeric TCR gene rearrangements involving J segments of the beta gene and V segments of the gamma or delta genes. As found previously for the transrearrangements between the gamma and delta genes, transrearrangements involving the beta gene were more abundant in DNA of the thymus than in DNA of the spleen, lymph node, bone marrow, or PBL. In addition, transrearrangements between Ig H chain V region segment and J segment of TCR delta chain were also found in DNA of normal thymus. Sequence analysis of the trans-rearrangement PCR products revealed structures closely resembling normal intragenic rearrangements, with N insertions and often D segments at the junctions between segments. The sequences analyzed suggest that transrearrangements arise through the action of normal lymphocyte recombinase, involve trans recognition of heptamer/nonamer recombination signals, and follow the 12 + 23 spacer rule. To test whether transrearrangements result from chromosomal rearrangements with breakpoints at the sites of Ag receptor genes, PCR was performed on the DNA of PBL from patients with ataxia telangiectasia, a disorder in which circulating lymphocytes often have numerous karyotypic abnormalities with breakpoints at the cytogenetic positions of these genes. Comparison of the results of PCR on this DNA and that of normal tissues demonstrated a substantially increased frequency for most types of transrearrangements investigated. These results support the interpretation that transrearrangement among TCR genes may occur by chromosomal rearrangement.
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PMID:Transrearrangements between antigen receptor genes in normal human lymphoid tissues and in ataxia telangiectasia. 165 8

In this paper, using polymerase chain reaction (PCR), we demonstrated the occurrence of hybrid genes formed by interlocus recombination between T cell receptor gamma (TCR-gamma) variable (V) regions and TCR-beta joining (J) regions in the peripheral blood lymphocytes (PBL) from normal individuals and patients with ataxia-telangiectasia (AT). Sequence analysis of the PCR-derived hybrid genes confirmed that site-specific V gamma-J beta recombination had occurred and showed that 10 of 23 genomic hybrid genes maintained a correct open reading frame. By dilution analysis, the frequency of these hybrid genes was 8 +/- 1/10(5) cells in normal PBL and 587 +/- 195/10(5) cells in AT PBL. These frequencies and the approximately 70-fold difference between the normal and AT samples are consistent with previous cytogenetic data examining the occurrence of an inversion of chromosome 7 in normal and AT PBL. We also demonstrated expression of these hybrid genes by PCR analysis of first-strand cDNA prepared from both normal and AT PBL. Sequence analysis of the PCR-amplified transcripts showed that, in contrast to the genomic hybrid genes, 19 of 22 expressed genes maintained a correct open reading frame at the V-J junction and correctly spliced the hybrid V-J exon to a TCR-beta constant region, thus allowing translation into a potentially functional hybrid TCR protein. Another type of hybrid TCR transcript was found in a which a rearranged TCR-gamma V-J exon was correctly spliced to a TCR-beta constant region. This form of hybrid gene may be formed by trans-splicing. These hybrid TCR genes may serve to increase the repertoire of the immune response. In addition, studies of their mechanism of formation and its misregulation in AT may provide insight into the nature of the chromosomal instability syndrome associated with AT. The mechanism underlying hybrid gene formation may be analogous to the mechanism underlying rearrangements between putative growth-affecting genes and the antigen receptor loci, which are associated with AT lymphocyte clones and lymphoid malignancies.
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PMID:Hybrid T cell receptor genes formed by interlocus recombination in normal and ataxia-telangiectasis lymphocytes. 169 65

Ataxia-telangiectasia (A-T) is inherited as an monogenetic autosomal recessive disease. Ataxia appears around 1 year of age and progresses until the patient becomes wheelchair-bound, usually by age 10. This progress correlates with deterioration of Purkinje cells in the cerebellum. Sinopulmonary infections are common in patients from some countries but not others. One-third of the patients develop a neoplasm, usually lymphoid, sometime during their shortened lives. Conventional doses of radiation therapy for such cancers are contraindicated since A-T patients are hypersensitive to ionizing radiation. Five complementation groups have been described, based on correction of radioresistant DNA synthesis of fused fibroblasts from pairs of patients. Chromosomal translocations are found in 5-10% of peripheral T cells from most patients and the translocation breakpoints involve sites of normal somatic DNA rearrangement. Thus, the A-T gene(s) effects several cell lineages, suggesting that it is a "housekeeping" gene. Other speculations on "candidate genes" are considered. Recent progress localizing A-T to chromosome 11q23 is reviewed.
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PMID:Speculations on the ataxia-telangiectasia defect. 171 44

It is the purpose of this review to analyse prevalence and pathogenesis of tumours occurring in the diverse conditions of primary and secondary immunodeficiencies. In general, most states of immunodeficiences are connected with a highly increased tumour risk. However, there is circumstantial evidence that immunodeficiency-related malignancies do not primarily result from an impaired immunosurveillance. With special regard to ataxia-telangiectasia it has been found that congenital chromosomal instability deregulates the maturation of immunocompetent lymphoid cells by interfering with their natural DNA rearrangements and eventually leads to false recombinatory events with oncogenetic consequences in a parallel way. Malignancies in primary common variable or in secondary (e.g. AIDS) immunodeficiency may result from an impaired immunity to oncogenic viruses or from chronic immune damage due to secondary autoimmune disorders.
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PMID:[Tumors in immunodeficiency syndromes]. 172 56

Ataxia telangiectasia (AT) is a primary immunodeficiency syndrome characterized by cerebellar ataxia, extrapyramidal signs, oculocutaneous telangiectasia, recurrent respiratory infections and development of malignancies. AT is a complex autosomal recessive disorder involving several systems other than lymphoid cells or the central nervous system. Such a diversity of abnormalities includes hypersensitivity of fibroblasts and lymphocytes to ionizing radiation (anomaly of DNA repair), non-random chromosomal rearrangements in lymphocytes, elevated serum level of alpha-fetoprotein, premature aging and endocrine disorders. A DNA processing or repair protein is the suspected common denominator in this pathology. Whatever the putative common underlying mechanism, AT patients have profound alterations of the humoral and cellular immune system whose mechanisms should be discussed in terms similar to those for other immunodeficiency diseases. The usual immunological abnormalities in this disease include decreased levels of CD 3 and CD 4 positive T lymphocytes, impaired delayed hypersensitivity, hypoplasia of thymus, decreased blast transformation in vitro in response to mitogen or antigenic stimulation, and decreased levels of serum IgA, IgE, and IgG 2 subclass. In this paper, the results of our recent studies on the defects of B cells in patients with AT were presented. (1) We found that the geometric means of IgA production in the supernatants of the lymphoblastoid cell lines established by EB virus, from all patients with AT, were significantly lower than those from healthy controls (P less than 0.01). (2) IgG subclasses of the patients' sera were also measured by ELISA, and IgG 4 was defective in four cases among six patients with AT.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:[Ataxia telangiectasia and characterization of its immunological disorders]. 215 3

Ataxia telangiectasia (A-T) is an autosomal recessive disorder characterised by progressive neurological degeneration, oculocutaneous telangiectasia, immunodeficiency and a high incidence of lymphoid tumours. A prerequisite to gaining a complete understanding of the basic defect that results in these features is the localization of the gene(s) involved. We report here a linkage analysis using seven polymorphic markers, which map to 11q22-23, on a sample of 35 consecutively obtained families from the British Isles showing this disorder. In a pairwise analysis, the strongest support for linkage was a lod score of 4.01 at zero recombination from Thy-1. This result supports a previous report showing linkage of the A-T gene to 11q22-23. We have also obtained evidence in a multipoint analysis for a more centromeric A-T-linked locus in the region between YNB 3.12/CJ52.208 and 2-7-1D6. This observation is also supported by inspection of the haplotypes of selected recombinants.
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PMID:Analysis of 7 polymorphic markers at chromosome 11q22-23 in 35 ataxia telangiectasia families; further evidence of linkage. 237 52

Ataxia-telangiectasia (AT) is a complex multiparametric disease associating oculocutaneous telangiectasias, cerebellar ataxia, elevated chromosomal aberration frequency and varied degrees of immunodeficiency. Recently a wasted mutant mouse (wst) has been described as an animal model of AT. We have looked in the wasted mutants for the presence of immune and endocrine abnormalities characteristic of AT. In contrast to the T cell immunodeficiency in AT, wasted mutants had a marked hypoplasia of all lymphoid organs, which affected both T and B lymphocyte subsets. The marked thymic atrophy appearing at the final stage of their disease did not modify the endocrine function of the thymic epithelium which produced normal levels of the thymic hormone thymulin. Although in vitro interleukin 2 (IL-2) production by splenic T cells in response to Con A was markedly diminished, these mice presented normal T and B cell proliferative responses to mitogens. Finally, no significant increase in serum alpha-fetoprotein level (a typical marker of AT) was found throughout the course of the disease. Although by many aspects, i.e. neurological disorder, chromosomal aberrations and early death, wasted mice presented similarities with human AT, major discrepancies in the typical features of immune abnormalities were found between the mouse model and the human disease.
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PMID:The wasted mutant mouse. II. Immunological abnormalities in a mouse described as a model of ataxia-telangiectasia. 242 78

Immunoglobulin and T cell receptor gene probes have been used to investigate cell lineage and monoclonality in lymphoid malignancies. In the present study we have used T cell receptor beta- and gamma-chain gene probes to screen for abnormal rearrangements of these genes in B lymphoblastoid cells from patients with ataxia-telangiectasia (A-T). No rearrangement of either gene was observed but deletion of a beta-chain gene allele is described for one A-T cell line. Expression of mRNA hybridizing to the beta-chain gene probe was demonstrated for two A-T homozygotes (brother and sister) as well as for their mother (heterozygote). This transcript was found to be truncated in all three cases.
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PMID:T cell receptor gene rearrangement and expression in ataxia-telangiectasia B lymphoblastoid cells. 254 55

Various cellular defects have been found in ataxia telangiectasia (A-T) cells including increased radiosensitivity, increased sensitivity to various chemical agents, a probable DNA repair defect and a defect in DNA synthesis. How these different features are related to each other is at present unknown. It has been suggested that there is a defect in A-T that acts in tissue differentiation as well as during growth and in the mature adult. This hypothesis is supported by the observations, for example, of an immature thymus present in patients, the production of alpha-fetoprotein, which results in a high serum level, and ovarian dysgenesis. A gene for A-T has recently been localized to chromosome region 11q22-23, a site involved in chromosomes translocations in some non-lymphoid leukaemias. At the chromosomal level the spontaneous abnormalities in A-T include, first, an increased frequency of cells showing chromosome translocations involving immune system genes that normally undergo rearrangement to form a functional product; secondly, the formation of telometric dicentrics in both lymphocytes and fibroblasts; and thirdly formation of long-lived chromosome damage following exposure to ionizing radiation and radiomimetic drugs. The gene defect underlying this disorder is unknown and distinguishing between primary and secondary effects of the mutant gene is difficult. We consider alternative models for retention of translocation T cells. First, it is possible that there is a defect in recognition of site-specific damage leading to retention of translocation cells that might otherwise be removed. Secondly, a feature common to the production of illegitimate T-cell receptor gene rearrangements and to formation of telomeric dicentric chromosomes in A-T cells is an increased period of time available for chromosome interchange, possibly due to a site-specific defect in strand break repair. It is possible that this defect may also prevent chromosome restitution following exposure of cells to ionizing radiation.
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PMID:Increased radiosensitivity and the basic defect in ataxia telangiectasia. 257 63

The analysis of various methods of thymic non-lymphoid cells (TNLC) culture in vitro was performed. The TNLC obtained in culture of small thymic fragments in Eagle's minimal essential medium with 30% of fetal calf serum have been found to be biologically active as indicated by their ability to enhance proliferative activity and Il-2 production of peripheral blood mononuclear cells derived from ataxia telangiectasia patients.
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PMID:Thymic non-lymphoid cells cultured for transplantation purposes. Immunostimulatory effect on ataxia telangiectasia peripheral blood mononuclear cells. 263 42


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