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Multicolor COBRA-FISH analysis of chronic myeloid leukemia reveals novel cryptic balanced translocations during disease progression.

Author:
  • Aikaterini Barbouti
  • Bertil Johansson
  • Mattias Höglund
  • Nils Mauritzson
  • Bodil Strömbeck
  • Per-Gunnar Nilsson
  • Hans J Tanke
  • Anne Hagemeijer
  • Felix Mitelman
  • Thoas Fioretos
Publishing year: 2002
Language: English
Pages: 127-137
Publication/Series: Genes, Chromosomes and Cancer
Volume: 35
Issue: 2
Document type: Journal article
Publisher: John Wiley & Sons

Abstract english

During the initial indolent chronic phase of chronic myeloid leukemia (CML), the t(9;22)(q34;q11), resulting in the Philadelphia chromosome (Ph), is usually the sole cytogenetic anomaly, but as the disease progresses into the accelerated phase (AP), and eventually into aggressive blast crisis (BC), secondary aberrations, mainly unbalanced changes such as +8, i(17q), and +Ph, are frequent. To date, molecular genetic studies of CML BC have mainly focused on alterations of well-known tumor-suppressor genes (e.g., TP53, CDKN2A, and RB1) and oncogenes (e.g., RAS and MYC), whereas limited knowledge is available about the molecular genetic correlates of the unbalanced chromosomal abnormalities. Balanced secondary changes are rare in CML AP/BC, but it is not known whether cryptic chromosomal translocations, generating fusion genes, may be responsible for disease progression in a subgroup of CML. To address this issue, we used multicolor combined binary ratio fluorescence in situ hybridization (FISH), which allows the simultaneous visualization of all 24 chromosomes in different colors, verified by locus-specific FISH in a series of 33 CML cases. Two cryptic balanced translocations, t(7;17)(q32-34;q23) and t(7;17)(p15;q23), were found in two of the five cases showing the t(9;22) as the only cytogenetic change. Using several BAC clones, the breakpoints at 17q23 in both cases were mapped within a 350-kb region. In the case with the 7p15 breakpoint, a BAC clone containing the HOXA gene cluster displayed a split signal, suggesting a possible creation of a fusion gene involving a member of the HOXA family. Furthermore, one case with a partially cryptic t(9;11)(p21-22;q23) and an MLL rearrangement as well as a previously unreported t(3;10)(p22;p12-13) were identified. Altogether, a refined karyotypic description was achieved in 12 (36%) of the 33 investigated cases, illustrating the value of using multicolor FISH for identifying pathogenetically important aberrations in CML AP/BC.

Keywords

  • Medical Genetics

Other

Published
  • ISSN: 1045-2257
Thoas Fioretos
E-mail: thoas [dot] fioretos [at] med [dot] lu [dot] se

Principal investigator

Translational Genomic and Functional Studies of Leucemia

+46 46 222 45 95

+46 70 334 33 67

BMC C13

66

Professor

Division of Clinical Genetics

+46 46 222 45 95

+46 70 334 33 67

BMC C13

66

Professor

Translational Genomic and Functional Studies of Leucemia

+46 46 222 45 95

+46 70 334 33 67

BMC C13

66