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

The disease ataxia telangiectasia (A-T) is a multifaceted disorder in which patients have an increased chance of developing a T-cell leukaemia, often with abnormalities of chromosome 14, but sometimes with rare translocations, like t(X;14)(q28;q11). We describe the cloning of the breakpoint of one such novel t(X;14) from an A-T patient. The translocation breaks within the T cell receptor alpha chain gene on chromosome 14 at band q11 and in a region of the X chromosome, within about 1 Mb of the telomere of the long arm. The patient subsequently developed T-cell prolymphocytic leukaemia (T-PLL), and molecular examination showed that the tumour cells carried the same t(X;14) breakpoint as that cloned from the premalignant cells. The same breakpoint could be detected in blood samples taken as much as 5 years prior to diagnosis of T-PLL. This suggests a role for the abnormality in the tumour development in this patient but implies that other mutational events were necessary for overt disease to become manifest.
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PMID:Molecular analysis of a new translocation, t(X;14)(q28;q11), in premalignancy and in leukaemia associated with ataxia telangiectasia. 128 20

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

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

Patients with ataxia telangiectasia (A-T) develop specific chromosome translocations, which may confer a proliferative advantage, resulting in the appearance of large clones in the peripheral blood lymphocytes. These lymphocytes are not malignant. Using in situ hybridisation techniques we have investigated a consistent 14q11 translocation breakpoint observed in a t(X;14)(q28;q11) translocation clone from each of two different patients and a t(14;14)(q11;q32) clone from a third patient. In all cases the chromosome translocation involved breakage within the alpha chain locus of the T cell receptor (TCR alpha), between the variable and constant regions, at 14q11. Chromosome rearrangement involving breakage within TCR alpha can therefore precede the development of malignancy. Further chromosomal rearrangement may be required in these patients, for progression to the leukaemic state.
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PMID:Breakage of the T cell receptor alpha chain locus in non malignant clones from patients with ataxia telangiectasia. 297 Apr 26

Abnormal T cell function is a feature of a spectrum of inherited and acquired diseases. We have detected a frequent restriction fragment length polymorphism in the human T cell antigen receptor beta-chain locus that may aid in the analysis of these disorders. A study of a panel of 18 normal individuals, testing for the presence of the polymorphism, showed it to account for 36% of the alleles in that group. In view of the fact that the T cell receptor beta-chain locus has been mapped to chromosome 7, and that the disease ataxia telangiectasia (AT) is associated both with abnormal T cell function and with chromosomal abnormalities of the same region of chromosome 7, we investigated the possibility that the polymorphism could demonstrate linkage of the T cell receptor locus to the gene for that disease. We demonstrated that the mutation causing AT did not lie within the beta-chain locus itself, and that there was preliminary evidence that the two loci were not closely linked. This polymorphism may provide a useful tool for the study of other genetic disorders associated with abnormalities of T cell function, as well as disorders associated with inherited or acquired abnormalities of chromosome 7.
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PMID:Detection of a frequent restriction fragment length polymorphism in the human T cell antigen receptor beta chain locus. A potential diagnostic tool. 299 49

Molecular analysis of somatic cell hybrids derived from T cells carrying a t(7;14)(q35;q32) chromosomal translocation from a patient with ataxia telangiectasia and T cell leukemia indicates that the breakpoint on chromosome 14 is proximal to the IgH locus and to the D14S1 locus, while the breakpoint on chromosome 7 involves the T cell receptor beta chain locus immediately 5' to J beta 1.5 on chromosome 7. The separation of V beta and C beta observed in somatic cell hybrids defined the orientation of the T cell receptor beta chain locus on chromosome 7 where the V beta genes are centromeric and the C beta genes are telomeric. A novel chromosomal alteration, undetected cytogenetically, was revealed as being an inversion with duplication of the distal band of chromosome 14q32. The importance of the 14q32 region in the leukemogenic process is discussed.
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PMID:Molecular analysis of a t(7;14)(q35;q32) chromosome translocation in a T cell leukemia of a patient with ataxia telangiectasia. 325 92

The T cell receptor alpha chain gene locus and the immunoglobulin heavy chain gene locus (IgH) have previously been mapped to the q11 and q32 positions respectively of the human chromosome 14. Both of these sites are also common breakpoints in lymphocytes from ataxia telangiectasia (A-T) patients. Using in situ hybridisation we show that the 14q32 breakpoint in an A-T non-leukaemic T cell clone with t(14;14) translocation, lies outside the IgH locus and proximal to it with respect to the centromere. The 14q11-14qter segment of the homologous chromosome 14 carrying the constant gene region of the alpha chain locus is translocated to this 14q32 position.
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PMID:The chromosome breakpoint at 14q32 in an ataxia telangiectasia t(14;14) T cell clone is different from the 14q32 breakpoint in Burkitts and an inv(14) T cell lymphoma. 348 54

Ataxia-telangiectasia (AT) is a primary genetic immunodeficiency disease predisposing to cancer. Approximately 40% of patients with AT develop malignancy, usually of the lymphoid system. Increased chromosome breakage in AT leads to rearrangements such as translocations and inversions. The preferred chromosome breakpoints in AT involve genes in the immune system: the immunoglobulin (Ig) gene loci in chromosome bands 2p12, 14q32, and 22q11 and the T cell receptor (TCR) gene loci in chromosome bands 7p13, 7q35, and 14q11. Identical chromosome breakpoints are observed in chromosome rearrangements in normal T cells, Burkitt's lymphoma, and adult T cell leukemia. Molecular analysis of these chromosome rearrangements reveals recombination between an oncogene and Ig or between Ig and TCR. In AT, chromosome rearrangements connect the immune system to lymphoid cancer.
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PMID:Chromosome changes connect immunodeficiency and cancer in ataxia-telangiectasia. 349 17

People with ataxia telangiectasia (AT) are at a higher than normal risk of T cell leukaemia and often have either non-malignant or malignant T cells with chromosomal abnormalities, typically t(14;14), inversion 14 or more rarely t(X;14). This provides a chance to study the pre-leukaemic phase of the disease. T cells have been studied with either t(14;14)(q11;q32.1) or t(X;14)(q28;q11) from two AT sisters of which the latter developed T cell leukaemia. The telomeric breakpoint of the t(14;14) was cloned and found to occur at 14q32.1 where known tumour-associated breakpoints are located, but the patient remains asymptomatic for leukaemia. Analysis of T cell populations in both patients showed that the cells containing the translocation became oligoclonal with respect to T cell receptor beta rearrangement and complete T cell receptor beta clonality was only established in the patient with t(X;14) by onset of overt disease. Therefore in these chronic diseases, chromosomal translocations can precede T cell receptor rearrangement suggesting a role for these abnormalities as early events of malignant outgrowth.
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PMID:Clonal evolution of malignant and non-malignant T cells carrying t(14;14) and t(X;14) in patients with ataxia telangiectasia. 803 21

T-cell lymphoproliferative diseases are often associated with recurrent chromosomal translocations involving T cell receptor genes (TCR) and genes that are thought to play a role in the pathogenesis of these diseases. Whereas numerous such genes have already been identified in acute T cell leukemias, no candidate gene has yet been identified to play a role in the heterogeneous group of T cell proliferations with a mature phenotype. We here report the molecular cloning of two examples of the rare but recurrent t(X;14) translocation. The first translocation was associated with a benign clonal proliferation in an ataxia telangiectasia patient and the second with a T cell prolymphocytic leukemia. Both translocations implicated the TCR alpha/delta locus and a common breakpoint region on chromosome Xq28. A previously unidentified gene, abnormally transcribed in both T cell proliferations, was characterized in the immediate proximity of the breakpoints. This Xq28 gene has no homology with known sequences, uses a complex alternative splicing pattern and demonstrates two short open reading frames. This gene, named MTCP-1 (Mature T Cell Proliferation-1) is the first candidate gene potentially involved in the leukemogenic process of mature T cell proliferations.
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PMID:MTCP-1: a novel gene on the human chromosome Xq28 translocated to the T cell receptor alpha/delta locus in mature T cell proliferations. 836 60


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