Jumping translocations of 11q in acute myeloid leukemia and 1q in follicular lymphoma

Jumping translocations: Short telomeres or pathogenic TP53 variants as underlying mechanism in acute myeloid leukemia and myelodysplastic syndrome?

Chromosomal rearrangements involving one donor chromosome and two or more recipient chromosomes are called jumping translocations. To date only few cases of acute myeloid leukemia (AML) and myelodysplastic syndrome (MDS) with jumping translocations have been described and the underlying mechanisms remain unclear. Here, we analyzed 11 AML and 5 MDS cases with jumping translocations. The cases were analyzed by karyotyping, FISH, telomere length measurement, and next-generation sequencing with an AML/MDS gene panel. Cases with jumping translocations showed significantly (P < .01) shorter telomeres in comparison to healthy age-matched controls. Additional neo-telomeres were found in two cases. In total, eight cases showed recipient chromosomes with a breakpoint in the centromeric region all of them harboring a pathogenic variant in the TP53 gene (n = 6) and/or a loss of TP53 (n = 5). By contrast, no pathogenic variant or loss of TP53 was identified in the six cases showing recipient chromosomes with a breakpoint in the telomeric region. In conclusion, our results divide the cohort of AML and MDS cases with jumping translocations into two groups: the first group with a telomeric breakpoint of the recipient chromosome is characterized by short telomeres and a possibly telomere-based mechanism of chromosomal instability formation. The second group with a centromeric breakpoint of the recipient chromosome is defined by mutation and/or loss of TP53. We, therefore, assume that both critically short telomeres as well as pathogenic variants of TP53 influence jumping translocation formation.

Characterization of an acquired jumping translocation involving 3q13.31-qter in a patient with de novo acute monocytic leukemia

We studied an adult with de novo acute monocytic leukemia and a dismal outcome where her leukemic cells harbored an acquired rare jumping translocation (JT). We used oligo-based array CGH (oaCGH) analysis, fluorescence in situ hybridization (FISH), and 24-color karyotyping to enhance the characterization of the JT. G-banding detected a JT involving the 3q13.3-qter chromosomal segment and the recipient chromosomal regions 17p, 8q, and 15q. Each clone with JT was associated with trisomy 8. oaCGH analysis revealed an additional submicroscopic deletion in 3q13.31 as well as small subtelomeric duplications on several chromosomes. Locus-specific FISH with BAC-based probes from the 3q13.31-q13.32 region showed great heterogeneity. Telomere FISH revealed significantly reduced telomeric content in the aberrant cells with JT compared with cytogenetically normal cells at diagnosis and in normal cells at complete remission. A literature search revealed two previous de novo AML-M5 cases of JT involving the 3q13.3-qter chromosomal segment and concomitant trisomy 8. In addition, a case with an unbalanced der(Y)t(Y;3)(q12;q13.31) and additional trisomy 8 was previously reported in a patient with de novo AML-M5. All of these cases had a dismal outcome. In the present case, and in the der(Y)t(Y;3) case, a concurrent submicroscopic deletion at 3q13.31 was observed affecting the TUSC7 gene. Duplication of 3q13.31-qter might be a non-random chromosomal abnormality with concomitant submicroscopic deletion at 3q13.31 occurring in rare cases of acute monocytic leukemia, being associated with adverse prognosis. The impact of shortened telomeres in forming the JT is reviewed.

Jumping Translocations in Myeloid Malignancies Associated With Treatment Resistance and Poor Survival

BACKGROUND

Jumping translocations (JT) are uncommon cytogenetic abnormalities involving nonreciprocal translocations of a single donor chromosome onto 2 or more chromosomes. The clinical characteristics and prognosis of JTs in patients with myeloid malignancies are not well described.

MATERIALS AND METHODS

We searched our cytogenetic database from 2003 to 2014 to identify cases of myeloid malignancies associated with a JT. These cases were cross-referenced with our clinical databases to determine patient characteristics, response to treatment and overall survival.

RESULTS

We identified 10 patients with myeloid malignancies and a JT: 4 cases of acute myeloid leukemia with myelodysplastic syndrome-related changes, 4 cases of myelodysplastic syndrome, and 2 cases of postpolycythemia myelofibrosis. The donor segment was derived from chromosome 1 in every case. The acquisition of a JT was a late occurrence, with a median time to JT development of 24.9 months (range, 0-248 months) from diagnosis. The overall response to treatment was poor, with no patients experiencing a response to conventional chemotherapy or hypomethylating agents. The median overall survival for the group was 9 months (95% confidence interval, 2.5-15.5) after identification of a JT.

CONCLUSION

The acquisition of a JT in patients with myeloid malignancies appears to be a late event and is associated with myelodysplasia. In our series, this was associated with a poor prognosis with a poor response to treatment, disease transformation to acute myeloid leukemia, and short overall survival.

Jumping translocations, a novel finding in chronic lymphocytic leukaemia

A jumping translocation (JT) is a rare cytogenetic aberration that can occur in haematological malignancy. It involves the translocation of the same fragment of donor chromosome onto two or more recipient chromosomes, typically in different cells. In this study, we describe the first series of chronic lymphocytic leukaemia (CLL) patients with JTs reported to date. Following a review of 878 CLL patient karyotypes, we identified 26 patients (3%) with 97 JTs. The most commonly occurring breakpoint in these translocations was 17p11.2. Loss of TP53 was identified prior to or at the same time as JT in 23 of 26 patients (88%). All patients eventually developed a complex karyotype. All but one patient has required treatment for CLL, with estimated median time to treatment of 11·5 months. This study establishes JTs as a recurrent abnormality found in CLL patients with aggressive disease. JTs contribute to complex karyotypes and, in many cases, are involved in chromosomal rearrangements that result in loss of the tumour suppressor gene TP53.

Distinct karyotypes in two offspring of a man with jumping translocation karyotype 45,XY,der(16)t(16;22)(q24;q11.2), -22 [59]/45,XY,der(1)t(1;22)(p36;q11.2), -22 [11]/45,XY,der(22)t(22;22)(p13;q11.2), -22 [10]

We examined a man and his daughter, who both had different jumping translocation karyotypes. The man's wife was pregnant and had been referred for prenatal diagnosis of the fetus. The karyotype of the husband's peripheral blood lymphocytes was 45,XY,der(16)t(16;22)(q24;q11.2), -22 [59]/45,XY,der(1)t(1;22)(p36;q11.2), -22 [11]/45,XY,der(22)t(22;22)(p13;q11.2), -22 [10]. The karyotype of the daughter's peripheral blood lymphocytes was 45,XX,der(16)t(16;22)(q24;q11.2), -22 [45]/45,XX,der(9)t(9;22)(q34;q11.2), -22 [30]/45,XX,der(5)t(5;22)(q35;q11.2), -22 [25]. The wife and the fetus both had a normal karyotype. To the best of our knowledge, the present familial transmitted jumping translocation has not been previously described and the jumping translocation in the husband and daughter did not cause any phenotypic abnormalities.

Jumping translocation in a case of de novo infant acute myeloid leukemia

An infant presented with fever and purulent discharge from the left ear, proptosis of the right eye, and hepatosplenomegaly. She was diagnosed with acute monoblastic leukemia on morphological and flowcytometric analysis of the bone marrow. Karyotyping showed a jumping translocation (JT) involving the long arm of chromosome 1 as the sole cytogenetic abnormality in 29 metaphases. The patient died within 2 months of diagnosis. The presence of JT in a de novo infant AML as a sole cytogenetic abnormality indicates its possible role in leukemogenesis unlike previous reports that have implicated its role in tumor progression only.

Jumping translocations

Jumping translocations (JT) are uncommon constitutional or acquired chromosome rearrangements involving one donor and several recipient chromosomes. They occur in various pathologic conditions and the mechanism of their formation remains elusive. A review of the literature showed that the major localizations of the breakpoints of JTs in human samples are nonrandomly located in pericentromeric and telomeric regions of chromosomes. Interestingly, comparison of the localization of the chromosomal breakpoints and of presence of interstitial DNA repeats showed differences between constitutional and acquired JTs suggesting differences in the mechanisms for the genesis of JTs and their consequences.

Molecular cytogenetic study of instability at 1q21∼q32 in adult acute lymphoblastic leukemia

In the present paper, we report a molecular cytogenetic study of 1q abnormalities associated with t(8;14)(q24;q32) in an adult common B acute lymphoblastic leukemia case with FAB-L2 morphology. The use of appropriate molecular cytogenetic probes allowed us to detect 13 different subclones showing heterogeneous chromosome 1 abnormalities. A complex pattern of rearrangements consisting of translocations, duplications, and inversions was observed. Breakage-fusion-bridge cycle and jumping translocation are hypothesized to have been involved in generating the large number of aberrations we detected.

A human interstitial telomere associates in vivo with specific TRF2 and TIN2 proteins

Mammalian telomeres are composed of long arrays of TTAGGG repeats that form a nucleoprotein complex which protects the chromosome ends. Human telomere function is known to require two TTAGGG repeat factors, TRF1 and TRF2, and several interacting proteins, but the mechanism by which the DNA/protein complex prevents end to end fusion in vivo has not been elucidated. In order to better understand the role of specific telomere-associated proteins in the organisation of chromosome ends, we have studied a patient with a rare chromosome rearrangement that has given rise to an interstitial telomere. Using specific antibodies and immuno-FISH on unfixed metaphase chromosomes, we show that the proteins TRF2 and TIN2 (TIN2 interacts with TRF1) co-localise with the interstitial TTAGGG repeats. Our results demonstrate, for the first time in humans, that TRF2 and TIN2 proteins associate with interstitial duplex TTAGGG repeats, in vivo. They confirm that double stranded-telomeric repeats, even when complexed with specific proteins, are not sufficient to create a functional telomere. Finally, they suggest a possible role for proteins in stabilising interstitial TTAGGG repeats.

Maintenance and characterization of an Epstein Barr virus-infected CD56-negative T cell lymphoma

T cell lymphoma carrying Epstein Barr virus (EBV(+) TL) is very rare among Western countries while it is much more common among Japanese. Here we report an EBV(+) TL which has been maintained for years by the use of mice with severe combined immune deficiency (SCID) mice. Lymphoma was obtained from a 55-year-old male suffering from oculomotor nerve palsy and lymphadenopathy. A small piece of biopsied tumor was transplanted into SCID mice and the lymphoma has been maintained for over 3 years with passages every 2 - 3 weeks. The maintained lymphoma, termed as TMS24, and the original lymphoma cells showed identical phenotype and genotype, including diffuse medium-sized cell morphology lacking granules, suppressor / cytotoxic immunophenotype and identical T cell receptor beta-chain gene rearrangement mode. Further, both were shown to carry an identical EBV clone in terms of the number of terminal repeats and the latency II-type restricted gene expression profile. Cytogenetically, TMS24 retained two characteristic chromosomal translocations of t(1;18)(q32;q21) and t(6;12)(p21;q24). Since only one cell line with such characters has been reported previously, TMS24 should be useful for detailed analysis of EBV(+) TL.