Characterization of a B-lymphocyte t(2;14) (p11;q32) translocation from an ataxia telangiectasia patient conferring a proliferative advantage on cells in vitro

Patients with the recessively inherited disorder ataxia telangiectasia (AT) are particularly prone to the development of both B-cell and T-cell tumours. Specific translocations involving T-cell gene rearrangements and an unknown locus 3' of IGH have been described in AT T-cell clone and tumour cells. We describe here a t(2;14)(p11;q32) translocation which was observed in nonmalignant short-term-cultured B lymphocytes from an AT patient. In vivo, the clone of cells grew from 1% to 6% of the total cell population over a period of 2 yr. Clonal translocations may therefore be associated with AT B cells, as well as AT T cells. B lymphocytes were transformed with Epstein-Barr virus, and the t(2;14) translocation cell was cellularly cloned. Using Southern filter analysis and in situ hybridisation to define more clearly the positions of the breakpoints, we show that the translocation at 14q32 involves a deletion within the IGH chain gene of at least J1, J2, DQ52, and sequences 1.5 kb 5' of DQ52 and that the breakpoint is either adjacent to the non-deleted JH sequences or upstream of these sequences, within the D or V regions, but proximal to all members of the VHII family of genes. The breakpoint at 2p11 is outside and proximal to IGK with respect to the centromere in an unknown gene. Sub-lines with an initially low proportion of translocation cells eventually became monoclonal in vitro for these cells. This suggests they have a growth advantage in vitro.     

Molecular involvement of the pvt-1 locus in a gamma/delta T-cell leukemia bearing a variant t(8;14)(q24;q11) translocation.

A highly malignant human T-cell receptor (TCR) gamma/delta+ T-cell leukemia was shown to have a productive rearrangement of the TCR delta locus on one chromosome 14 and a novel t(8;14)(q24;q11) rearrangement involving the J delta 1 gene segment on the other chromosome 14. Chromosome walking coupled with pulsed-field gel electrophoretic (PFGE) analysis determined that the TCR J delta 1 gene fragment of the involved chromosome was relocated approximately 280 kb downstream of the c-myc proto-oncogene locus found on chromosome band 8q24. This rearrangement was reminiscent of the Burkitt's lymphoma variants that translocate to a region identified as the pvt-1 locus. Sequence comparison of the breakpoint junctions of interchromosomal rearrangements in T-cell leukemias involving the TCR delta-chain locus revealed novel signal-like sequence motifs, GCAGA(A/T)C and CCCA(C/G)GAC. These sequences were found on chromosome 8 at the 5' flanking site of the breakpoint junction of chromosome 8 in the TCR gamma/delta leukemic cells reported here and also on chromosome 1 in T-cell acute lymphocytic leukemia patients carrying the t(1;14)(p32;q11) rearrangement. These results suggest that (i) during early stages of gamma delta T-cell ontogeny, the region 280 kb 3' of the c-myc proto-oncogene on chromosome 8 is fragile and accessible to the lymphoid recombination machinery and (ii) rearrangements to both 8q24 and 1p32 may be governed by novel sequence motifs and be subject to common enzymatic mechanisms.     

Distal trisomy 14q

Summary Two cases of chromosome 14 rearrangements with partial duplication which occurred de novo were analyzed by Southern blot analysis using IGH, D14S1 and PI probes. In the first case, with a 46,XX,14p+ karyotype, our study confirms that the additional material on chromosome 14p+ results from a duplication of the 14q region containing the IGH, D14S1 and PI loci. In the second case, our study reveals only one 14q32 locus per chromosome 14 indicating that the extra material does not contain the 14q32 region. Our results demonstrate that molecular probes of the 14q32 region are valuable tools for the characterisation of chromosome 14 abnormalities appearing de novo.     

New data on clonal anomalies of chromosome 14 in ataxia telangiectasia: tct (14;14) and inv(14)

Summary From a series of 53 patients with ataxia telangiectasia, two large clones with a t tan or tct(14;14) and two with an inv(14) were observed among phytohaemagglutinin (PHA)-stimulated lymphocytes. Smaller clones with the same inv(14) were observed in two other cases. Similar breakpoints may exist, both for t(14;14) and inv(14): q11.1/q11.2 and q32, and it is postulated that the rearrangements are related to a recombination of the -chain of the T-cell receptor and IgH clusters of genes.     

Familial reciprocal translocation t(17;19) (q11.2;q13.2) associated with neurofibromatosis type 1, including one patient with non-Hodgkin lymphoma and an additional t(14;20) in B lymphocytes

The cosegregation of a reciprocal translocation t(17;19) (q11.2;13.2) with neurofibromatosis type 1 in three generations suggested that the breakpoint on chromosome 17 involved the NF1 gene. In order to map the breakpoint, we analysed DNAs of patients using parts of the NF1 gene as probes. Southern analysis revealed that the chromosome 17 breakpoint lies within intron 23 of the NF1 gene. One of the patients of the family developed a non-Hodgkin lymphoma. An additional translocation t(14;20) (q32;13.1) in his B lymphocytes points to a gene on chromosome 20 that is juxtaposed to the IGH locus on 14q32, and that may be of relevance for the development of this tumor type.     

Molecular cloning of a DNA fragment from human chromosome 14(14q11) involved in T-cell malignancies.

To isolate DNA segments specific to chromosome band 14q11, which has been implicated in a number of human T-cell malignancies, a genomic DNA library was prepared from a variant cell subline of the human lymphoblastic KE37 cell line. This subline (KE37-R) bears a t(8;14) (q24;q11) translocation, and the breakpoint on the resulting chromosome 8q+ has been located at the 3' end of the third c-myc exon. Three molecular clones were isolated by screening the library with a c-myc exon 3 probe, and one of them (lambda K40) was analyzed in detail. It contains a 15-kb insert consisting of 4.5 kb of sequence from chromosome 8 (e.g., downstream of c-myc exon 3) and sequences from chromosome 14. The origin of these latter sequences was established by hybridizing DNA from chromosomes sorted by flow cytometry to a lambda K40 subclone containing only chromosome 14 presumptive sequences and by Southern blot analysis of rodent X human somatic hybrid cell DNA with the same probe. No cross-hybridization was found between the lambda K40 clone and a cDNA clone for the alpha chain T-cell receptor gene which is also located in 14q11. A preliminary survey of DNAs from human T-cell malignancies with a probe corresponding to chromosome 14 sequences of lambda K40 clone revealed for some of them restriction patterns different from those of the germ line DNA. The fact that the rearrangement observed in a leukemic patient was not found in DNA from lymphocytes obtained during remission excluded any polymorphism.(ABSTRACT TRUNCATED AT 250 WORDS)     

Unbalanced 1q whole-arm translocation resulting in der(14)t(1;14)(q11-12;p11) in myelodysplastic syndrome

Unbalanced whole-arm translocations (WATs) of the long arm of chromosome 1, resulting in complete trisomy 1q, are chromosomal abnormalities detectable in both solid tumors and hematologic neoplasms. Among the WATs of 1q to acrocentric chromosomes, a few patients with der(1;15) described as a dicentric chromosome have been reported so far, whereas cases of der(1;14) are much rarer. We report on a case of der(1;14) detected as single anomaly in a patient with myelodysplastic syndrome. The aim of our work was to investigate the breakpoints of the (1;14) translocation leading to the der(1;14). Fluorescence in situ hybridization (FISH) experiments have been performed on chromosome preparations from bone marrow aspirate, using specific centromeric probes of both chromosomes, as well as a probe mapping to 1q11 band. FISH results showed that in our patient the derivative chromosome was monocentric with a unique centromere derived from chromosome 14. The breakpoints of the translocation were located in the short arm of chromosome 14 and in the long arm of chromosome 1, between the alphoid D1Z5 and the satellite II domains. The 1q breakpoint was within the pericentromeric region of chromosome 1, which is notoriously an unstable chromosomal region, involved in different chromosomal rearrangements.     

Molecular cytogenetics of IGH rearrangements in non-Hodgkin B-cell lymphoma

Rearrangements involving the IGH gene have been identified in about 50% of non-Hodgkin B-cell lymphomas (NHLs) and correlated to clinically relevant subgroups. However, the detection rate largely varied with the technique used. We analyzed the incidence of IGH rearrangements using several fluorescence in situ hybridization (FISH) techniques on metaphases obtained from 96 patients with nodal NHL. An IGH rearrangement was identified in 71 cases (74%). A t(14;18)(q32;q21) was found in 37 of the 42 follicular lymphomas (88.1%) studied and a t(11;14)(q13;q32) in 12 of the 14 mantle cell lymphomas (85.7%). IGH rearrangements were identified in 21 of the 40 diffuse large B-cell lymphomas (52.5%), including seven t(14;18)(q32;q21) and four t(3;14)(q27;q32). Conventional cytogenetics was uninformative in several cases. However, the complemented analysis using 24-color FISH, chromosomal whole paints, telomeric probes and locus specific identifiers enabled us to characterize complex and/or masked IGH translocations in follicular lymphomas and mantle cell lymphomas and to identify all the chromosomal partners involved in IGH rearrangements in diffuse large B-cell lymphomas. This study shows the interest of using metaphase FISH in addition to conventional cytogenetics. Following banding techniques, FISH with the IGH dual color probe can be the first approach in NHL, after which chromosome painting and 24-color FISH can be used to identify the chromosomal partners involved in IGH rearrangements. The identification of these genes is of utmost importance for a better understanding of the molecular mechanisms involved in the genesis of lymphoma.     

Human T-cell tumours containing chromosome 14 inversion or translocation with breakpoints proximal to immunoglobulin joining regions at 14q32.

T-cell tumours are frequently found to carry an inversion of chromosome 14 (inv(14)) (q11;q32) or more rarely a chromosome 14 translocation t(14;14) with the same cytogenetic breakpoints (q11;q32). We have examined the molecular junctions of an inv(14) and a translocation t(14;14) using T-cell receptor (TCR) alpha joining (J) region probes. Both of these chromosomal abnormalities have breakpoints within the TCR J alpha locus at 14q11 and both have breakpoints which are proximal (i.e. on the centromeric side) to the immunoglobulin heavy chain JH region at 14q32. The cloned segments corresponding to the junctions at 14q32 are not associated with obvious immunoglobulin-like sequences. This contrasts to the previously described inv(14) in the cell line SUP-T1 and places a potential cluster of chromosome 14 breakpoints downstream of the Ig JH locus. The possible role of the varying breakpoints in the development of these tumours is discussed.     

SNP analysis of minimally evolved t(14;18)(q32;q21)-positive follicular lymphomas reveals a common copy-neutral loss of heterozygosity pattern

Follicular lymphoma (FL) cases with a t(14;18)(q32;q21) and minimal or no additional karyotypic alterations, such as copy number gains and losses and/or chromosomal rearrangements, may exhibit pathologic features and a clinical behavior similar to those with more complex karyotypes. This study sought to investigate whether the copy-neutral loss of heterozygosity (cnLOH) profiles of these minimally evolved t(14;18)(q32;q21)-positive follicular lymphoma (MEV-FL) cases are similar to or different from the majority of FL cases with more karyotypic alterations. Affymetrix SNP 6.0 array analysis was applied to the tumor genomes of 23 MEV-FL biopsy samples to assess for the presence of cnLOH. These cases carried either a single or no chromosomal abnormality in addition to t(14;18)(q32;q21) as determined by karyotyping. We found that, although these MEV-FL cases had simple karyotypes, they showed very similar cnLOH profiles as compared to cytogenetically complex cases. The most frequent regions affected by cnLOH were 1p (17%), 6p (17%), 12q (13%) and 16p (13%). Our study suggests that cnLOH alterations may serve as important contributors to the pathological and clinical manifestations of FL.     

Partial trisomy 14q due to maternal t(4;14)(p16;q32) in a dysmorphic newborn

Partial Trisomy 14q is a rare chromosomal disorder that mostly results from a parental translocation. We report here a newborn boy with partial trisomy 14q and dysmorphic features that are compatible with previously reported cases. Conventional cytogenetic analysis revealed an extra chromosomal segment at the end of the short arm of chromosome 4. In order to determine the origin of this chromosome region we used subtelomeric FISH technique. Based on the results of these cytogenetic studies and the physical examination, this dysmorphic case was diagnosed as partial trisomy of 14q and his karyotype determined as 46 XY, der(4)t(4;14)(p16;q32) resulting from a balanced maternal translocation identified as 46,XX, t(4;14)(p16;q32).     

(11; 14) translocation in three boys with acute lymphoblastic leukemia of T-cell immunophenotype

Three boys, 12, 15 and 5 years old are presented with acute lymphoblastic leukemia resp. Non-Hodgkin's lymphoma with leukemic transformation. Blast cells could be characterized as being of T-cell origin. Hand mirror variant was the predominant morphologic feature of the blast cells in two patients. Chromosome analysis of the leukemic blast cells revealed a pseudodiploid (modal chromosome number = 46) karyotype in two patients and a pseudotetraploid (modal chromosome number = 92) in one patient. A chromosome translocation (11; 14) with breakpoints at (p 13; q 13) (within the human T-cell receptor alpha chain locus!) was found in the leukemic cells of all three cases plus an additional t (7; 9) (q 22; p 13) in one patient.     

Exceptional complex chromosomal rearrangement and microdeletions at the 4q22.3q23 and 14q31.1q31.3 regions in a patient with azoospermia

In this report we describe the first patient ever found to have azoospermia in association with both exceptional complex chromosomal rearrangements and microdeletions at two translocation breakpoints. A 36-year-old male who had been suffering from male factor infertility was admitted to our clinic. The patient also displayed mild dysmorphia. An analysis of the patient's semen revealed azoospermia. GTG banding revealed the presence of an exceptional complex chromosomal rearrangement involving chromosomes 1, 4, 10 and 14. Using subtelomeric FISH analysis, the patient's karyotype was designated as 46,XY,t(1;10)(q43q44;q21q26.1)(CEB108/T7+,D1S3738-;10PTEL006+,D10S2290+, D1S3738+), ins(14;4) (q31.3;q23q33)(D14S1420+; D4S3359+, D4S2930+). Array-CGH analysis revealed two microdeletions at the 4q22.3q23 and 14q31.1q31.3 chromosomal regions. We suggest that microdeletions at the 4q22.3q23 and 14q31.1q31.3 chromosomal regions associated with both an exceptional complex chromosomal rearrangement and the Homo sapiens chromosome 4 open reading frame 37 (C4orf37) gene located at the 4q22.3q23 region might be associated with male factor infertility.     

Localization of a DNA segment encompassing four tRNA genes to human chromosome 14q11 and its use as an anchor locus for linkage analysis

The chromosomal location of an 8.2-kb genomic fragment encompassing a cluster of four human tRNA genes has been determined by three complementary methods including Southern analysis of human/rodent somatic cell hybrids, in situ hybridization, and genetic linkage analysis. This tRNA cluster (TRP1, TRP2, and TRL1) is located near the T-cell receptor alpha (TCRA) locus at 14q11, and several RFLPs were detected at this site. These RFLPs and those at the TCRA and MYH7 (cardiac beta-MHC gene) loci have been used to type all informative members of the CEPH pedigrees. This has permitted ordering of these three gene loci and two anonymous probes (D14S26 and D14S25) in a 20-cM interval just below the centromere of chromosome 14. Based upon the chromosomal location and the polymorphisms at this site, one or more members of this gene cluster could serve as a useful anchor locus on chromosome 14.     

Partial duplication 14q/deletion 2q in two sibs due to t(2;14) (q37.1;q31.2) pat

Two siblings are described with duplication 14q/deletion 2q due to a paternal translocation (2;14) (q37.1;q31.2). The first one, a boy, born at term, lived 14 days. The second one, a female foetus, was born after induced labour when the anomaly was discovered by way of amniocentesis. They both had almost identical phenotypes. From a study of the literature it is inferred that a typical asymmetric head form, low set abnormal ears, micrognathia, long upper lip, rib anomalies, camptodactyly, long fingers and contractures are prominent features of the syndrome.     

Intragenic breakpoint within RAD51L1 in a t(6;14)(p21.3;q24) of a pulmonary chondroid hamartoma

Rearrangements involving chromosome region 14q23-->q24 represent a main cytogenetic subgroup in a variety of benign solid tumors. Recently, in uterine leiomyomas containing the classical t(12;14)(q15;q23-->q24), the primary chromosome 14 target gene was identified as the protein kinase-encoding gene RAD51L1. In this report we show that RAD51L1 is also involved in the frequently occurring t(6;14) (p21;q23-->q24) in pulmonary chondroid hamartomas.     

Physical mapping of probes within 14q32, a subtelomeric region showing a high recombination frequency

The genetic linkage map of chromosome 14q32 contains 11 loci which span a distance of more than 60 cM. We have assigned 10 of these loci and the AKT1 proto-oncogene to segments of 14q32, using breakpoints derived from four independent chromosomal deletions or rearrangements. The most telomeric breakpoint was found in a proband (HSC 6) carrying a ring-14 chromosome. HSC 6 is monosomic for the distal part of 14q32, which contains the immunoglobulin heavy-chain locus (IGH), and random markers D14S20, D14S19, and D14S23. Two other chromosomal breakpoints, found in probands HSC 121 and HSC 981, could not be distinguished from each other using DNA probes, although the cytogenetic breakpoints appeared to be different at 14q32.32 and 14q32.31, respectively. The region between the breakpoints of HSC 6 and HSC 121 contains AKT1, D14S1, D14S17, and D14S16. The entire telomeric band 14q32 is assumed to contain about 10% of chromosome 14, or approximately 10 Mb. The 8 most telomeric loci, including D14S1, map to 14q32.32-qter, which measures only several megabases. However, these loci span a genetic distance of 23 cM. The high recombination frequency contrasts with the observation that two of the gamma genes in the IGH constant region show a high degree of linkage disequilibrium, though 180 kb apart. This finding suggests that a telomeric localization per se does not lead to a higher recombination frequency and favors the hypothesis that the higher recombination frequency at the telomeres may be due to specific "hot spots" for recombination.     

A subpopulation of t(2;14)(p11;q32) cells in ataxia telangiectasia B lymphocytes

Summary Partially purified B cells from ataxia telangiectasia (A-T) patients and normal individuals were stimulated with Staphylococcus aureus Cowan I organisms (SAC). High levels of apparently random rearrangements were seen in the A-T B cells only. In addition a t(2;14)(p11;q32) rearrangement was identified in B cells from more than one patient.