Jumping translocations of 3q in acute promyelocytic leukemia

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 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.

Genome-wide search for loss of heterozygosity in Burkitt lymphoma cell lines

The molecular biological characteristics of Burkitt lymphoma (BL), in addition to the presence of the Epstein-Barr virus (EBV) in some forms, relies on well-characterized alterations, such as MYC translocations and TP53 inactivations. To ascertain the number and location of other genome alterations, we used 191 polymorphic markers in a genome-wide search for loss of heterozygosity (LOH) in 31 Burkitt lymphoma cell lines and their normal counterparts. We were able to distinguish two types of altered allelic patterns: a bona fide LOH profile, indicative of deletion (LOH), and a profile indicative of increased dosage (ID). The former type was most frequent at chromosome arm 17p, most likely indicating TP53 gene inactivation. Increased dosage at 1q was found almost exclusively in non-EBV cell lines (P < 0.00004) and correlated well with karyotypic abnormalities affecting region 1q21-25. Our results suggest that a gene important for BL pathogenesis is located in region 1q21-25 and that the activation of this gene mimics the effects of EBV.

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

Jumping translocation is a rare cytogenetic aberration in leukemia and lymphoma, and its etiologic mechanisms are not clearly known. We report two cases with jumping translocations. One had follicular lymphoma and jumping translocations of 1q onto the telomeric regions of 5p, 9p, and 15q in three cell lines, co-existing with the specific translocation t(14;18)(q32;q21). The second case had acute myeloid leukemia (AML) and jumping translocations of 11q as the sole aberration, onto multiple derivative chromosomes in each of the abnormal cells. A total of 17 telomeric regions were seen as the recipients of 11q in this case, and 9q was always involved as one of the recipients in all abnormal cells. Fluorescence in situ hybridization (FISH) confirmed the identification of 11q material in the derivative chromosomes. While 1q has been the most common donor of acquired jumping translocations, this is the first report on jumping translocations of 11q. Different from all previously reported jumping translocations which involve only one recipient in each cell line and lead to a mosaic trisomy, multiple recipients in most of the abnormal cells in this case had led to a tetrasomy, or a pentasomy of 11q. The pattern of chromosome involvement as the recipients of 11q appears to show a continuing evolutionary process of jumping, stabilization, and spreading of the donor material into other chromosomes. Somatic recombinations between the interstitial telomeric or subtelomeric sequences of a derivative chromosome and the telomeric sequences of normal chromosomes are believed to be the underlying mechanism of jumping translocations and their clonal evolution.

Jumping translocation in acute leukemia of myelomonocytic lineage: a case report and review of the literature

Jumping translocation (JT) is a very rare cytogenetic event, occurring especially in cancer. We describe a case of secondary acute monocytic leukemia (AML5b) with a JT involving the 3q13-3qter segment and leading to a partial trisomy 3. Each clone with JT was associated with trisomy 8 or tetrasomy 8. The literature of JT in AML cases is reviewed: only 13 cases of AML associated with JT have been previously described, seven of which are AML4/5 FAB subtype. Jumping translocation involvement in leukemogenesis is discussed. Leukemia (2000) 14, 119-122.