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Yin Law JH, Au CH, Leung AWS, Leung HCM, Wong EYL, Ip BBK, Ho DNY, Ma SY, Chan HMH, Chiu EKW, Chim JCS, Liang RHS, Wan TSK, Ma ESK. A multi-modal molecular characterization of the Philadelphia translocation featuring long read sequencing. Gene 2025; 950:149370. [PMID: 40024301 DOI: 10.1016/j.gene.2025.149370] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2024] [Revised: 02/22/2025] [Accepted: 02/25/2025] [Indexed: 03/04/2025]
Abstract
OBJECTIVE Clinically significant structural variation (SV), notably chromosomal translocation, results in the formation of fusion genes that drive leukaemogenesis. Detection of SVs is vital in clinical diagnosis, prognosis and therapy of haematological malignancies. Current methods for SV identification are low in sensitivity for cryptic cases and time-consuming for complex cases. This study investigated the feasibility of long read sequencing as an approach for SV detection and precise breakpoint characterization. METHODS Six archival samples, including 4 bone marrow blood samples (F/66 B-ALL, F/25 B-ALL, M/53 CML, F/34 B-ALL) and 1 cytogenetic cell pellet each in cell culture medium (M/52 CML) or Carnoy's fixative (M/44 CML) with known and previously characterized BCR::ABL1 fusion transcript were selected for study. The genomic DNA was extracted from each case for further breakpoint characterization by long read sequencing (MinION R9.4.1 flow cell, Oxford Nanopore Technologies, UK). RESULTS All the genomic breakpoints were concordant with the RNA fusion transcript breakpoints. Three typical (e1a2, e13a2, and e14a2) and 3 variant (e23a2Ins52, e8a2, and e13a2ins74) BCR breakpoints were identified. CONCLUSION Using the Ph translocation as an example, long read sequencing is a promising alternative method to detect SV, revolutionizing detection of chromosomal translocation to a higher precision. A more comprehensive spectrum of SV can be resolved along with cytogenetic results, enabling precise diagnosis and personalized monitoring of haematological malignancies.
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Affiliation(s)
- Janet Hei Yin Law
- Division of Molecular Pathology, Department of Pathology, Hong Kong Sanatorium & Hospital, Hong Kong, China
| | - Chun Hang Au
- Division of Molecular Pathology, Department of Pathology, Hong Kong Sanatorium & Hospital, Hong Kong, China
| | - Amy Wing-Sze Leung
- Division of Molecular Pathology, Department of Pathology, Hong Kong Sanatorium & Hospital, Hong Kong, China
| | - Henry C M Leung
- Division of Molecular Pathology, Department of Pathology, Hong Kong Sanatorium & Hospital, Hong Kong, China
| | - Elaine Y L Wong
- Division of Molecular Pathology, Department of Pathology, Hong Kong Sanatorium & Hospital, Hong Kong, China
| | - Beca B K Ip
- Division of Molecular Pathology, Department of Pathology, Hong Kong Sanatorium & Hospital, Hong Kong, China
| | - Dona N Y Ho
- Division of Molecular Pathology, Department of Pathology, Hong Kong Sanatorium & Hospital, Hong Kong, China
| | - Shing Yan Ma
- Specialist in Haematology & Haematological Oncology, Hong Kong, China
| | - Helen M H Chan
- Specialist in Haematology & Haematological Oncology, Hong Kong, China
| | - Edmond K W Chiu
- Specialist in Haematology & Haematological Oncology, Hong Kong, China
| | - James C S Chim
- Department of Medicine and Comprehensive Oncology Centre, Hong Kong Sanatorium & Hospital, Hong Kong, China
| | - Raymond H S Liang
- Department of Medicine and Comprehensive Oncology Centre, Hong Kong Sanatorium & Hospital, Hong Kong, China
| | - Thomas S K Wan
- Division of Molecular Pathology, Department of Pathology, Hong Kong Sanatorium & Hospital, Hong Kong, China
| | - Edmond S K Ma
- Division of Molecular Pathology, Department of Pathology, Hong Kong Sanatorium & Hospital, Hong Kong, China.
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Tang Z, Toruner GA, Tang G, Cameron Yin C, Wang W, Hu S, Thakral B, Wang SA, Miranda RN, Khoury JD, Medeiros LJ. Chronic myeloid leukemia with insertion-derived BCR-ABL1 fusion: redefining complex chromosomal abnormalities by correlation of FISH and karyotype predicts prognosis. Mod Pathol 2020; 33:2035-2045. [PMID: 32404952 DOI: 10.1038/s41379-020-0564-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2019] [Revised: 04/24/2020] [Accepted: 04/24/2020] [Indexed: 12/29/2022]
Abstract
Chromosomal insertion-derived BCR-ABL1 fusion is rare and mostly cryptic in chronic myeloid leukemia (CML). Most of these cases present a normal karyotype, and their risk and/or prognostic category are uncertain. We searched our database and identified 41 CML patients (20 M/21 F, median age: 47 years, range 12-78 years) with insertion-derived BCR-ABL1 confirmed by various FISH techniques: 31 in chronic phase, 1 in accelerated phase, and 9 in blast phase at time of diagnosis. Conventional cytogenetics analysis showed a normal karyotype (n = 19); abnormal karyotype with morphologically normal chromosomes 9 and 22 (n = 5); apparent ins(9;22) (n = 2) and abnormal karyotype with apparent abnormal chromosomes 9, der(9) and/or 22, der(22) (n = 15). The locations of insertion-derived BCR-ABL1 were identified on chromosome 22 (68.3%), 9 (29.3%), and 19 (2.4%). Complex chromosomal abnormalities were often overlooked by conventional cytogenetics but identified by FISH tests in many cases. After a median follow-up of 58 months (range 1-242 months), 11 patients died, and 3 lost contact, while the others achieved different cytogenetic/molecular responses. The locations of BCR-ABL1 (der(22) vs. non-der(22)) and the karyotype results (complex karyotype vs. noncomplex karyotype) by conventional cytogenetics were not associated with overall survival in this cohort. However, redefining the complexity of chromosomal abnormality by correlating karyotype and FISH findings, CML cases with simple chromosomal abnormalities had a more favorable overall survival than that with complex chromosomal abnormalities. We conclude that insertion-derived BCR-ABL1 fusions often involve complex chromosomal abnormalities which are overlooked by conventional cytogenetics, but can be identified by one or more FISH tests. We also suggest that the traditional cytogenetic response criteria may not apply in these patients, and the complexity of chromosomal abnormalities redefined by correlating karyotype and FISH findings can plays a role in stratifying patients into more suitable risk groups for predicting prognosis. (Word count: 292).
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Affiliation(s)
- Zhenya Tang
- Department of Hematopathology, The University of Texas MD Anderson Cancer Center, Houston, TX, 77030, USA.
| | - Gokce A Toruner
- Department of Hematopathology, The University of Texas MD Anderson Cancer Center, Houston, TX, 77030, USA
| | - Guilin Tang
- Department of Hematopathology, The University of Texas MD Anderson Cancer Center, Houston, TX, 77030, USA
| | - C Cameron Yin
- Department of Hematopathology, The University of Texas MD Anderson Cancer Center, Houston, TX, 77030, USA
| | - Wei Wang
- Department of Hematopathology, The University of Texas MD Anderson Cancer Center, Houston, TX, 77030, USA
| | - Shimin Hu
- Department of Hematopathology, The University of Texas MD Anderson Cancer Center, Houston, TX, 77030, USA
| | - Beenu Thakral
- Department of Hematopathology, The University of Texas MD Anderson Cancer Center, Houston, TX, 77030, USA
| | - Sa A Wang
- Department of Hematopathology, The University of Texas MD Anderson Cancer Center, Houston, TX, 77030, USA
| | - Roberto N Miranda
- Department of Hematopathology, The University of Texas MD Anderson Cancer Center, Houston, TX, 77030, USA
| | - Joseph D Khoury
- Department of Hematopathology, The University of Texas MD Anderson Cancer Center, Houston, TX, 77030, USA
| | - L Jeffrey Medeiros
- Department of Hematopathology, The University of Texas MD Anderson Cancer Center, Houston, TX, 77030, USA
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Wan TSK. Cancer cytogenetics: methodology revisited. Ann Lab Med 2014; 34:413-25. [PMID: 25368816 PMCID: PMC4215412 DOI: 10.3343/alm.2014.34.6.413] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2014] [Revised: 07/31/2014] [Accepted: 10/06/2014] [Indexed: 01/14/2023] Open
Abstract
The Philadelphia chromosome was the first genetic abnormality discovered in cancer (in 1960), and it was found to be consistently associated with CML. The description of the Philadelphia chromosome ushered in a new era in the field of cancer cytogenetics. Accumulating genetic data have been shown to be intimately associated with the diagnosis and prognosis of neoplasms; thus, karyotyping is now considered a mandatory investigation for all newly diagnosed leukemias. The development of FISH in the 1980s overcame many of the drawbacks of assessing the genetic alterations in cancer cells by karyotyping. Karyotyping of cancer cells remains the gold standard since it provides a global analysis of the abnormalities in the entire genome of a single cell. However, subsequent methodological advances in molecular cytogenetics based on the principle of FISH that were initiated in the early 1990s have greatly enhanced the efficiency and accuracy of karyotype analysis by marrying conventional cytogenetics with molecular technologies. In this review, the development, current utilization, and technical pitfalls of both the conventional and molecular cytogenetics approaches used for cancer diagnosis over the past five decades will be discussed.
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Affiliation(s)
- Thomas S. K. Wan
- Haematology Division, Department of Pathology, The University of Hong Kong, Hong Kong
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Abstract
SUMMARY Cytogenetic analysis is now considered a mandatory investigation in the diagnostic work-up of hematologic malignancies. Recurring structural aberrations serve as powerful markers not only for diagnosis and prognosis of these conditions, but also guide the selection of targeted drugs for personalized oncology. The FISH approach is established as an indispensable tool to complement conventional cytogenetics, in addition to basic and clinical research applications. FISH is used to identify specific chromosomal aberrations through the detection of target DNA sequences by fluorescently labeled DNA probes. Multicolor FISH analysis allows the accurate identification of recurring translocations in neoplastic cells by means of genomic probes that flank the breakpoints. This review summarizes the panel of FISH probes for selection and the current utilization of these FISH techniques in unraveling chromosomal aberrations. The niche of FISH analysis is also highlighted. Variant signal patterns of the clinically useful FISH probes for hematologic oncology illustrated here provide useful interpretative reference for molecular pathology laboratories. In addition, the recent application of FISH tests in contributing information on drug targets at the genomic level to support personalized oncology will also be discussed.
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Affiliation(s)
- Thomas SK Wan
- Division of Haematology, Department of Pathology, Queen Mary Hospital, The University of Hong Kong, 102, Pokfulam Road, Hong Kong, China
| | - Edmond SK Ma
- Department of Pathology, Hong Kong Sanatorium & Hospital, Hong Kong, China
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Bennour A, Bellâaj H, Ben Youssef Y, Elloumi M, Khelif A, Saad A, Sennana H. Molecular cytogenetic characterization of Philadelphia-negative rearrangements in chronic myeloid leukemia patients. J Cancer Res Clin Oncol 2011; 137:1329-36. [PMID: 21739181 DOI: 10.1007/s00432-011-1002-4] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2011] [Accepted: 06/27/2011] [Indexed: 01/13/2023]
Abstract
BACKGROUND The BCR/ABL gene rearrangement is generated by a reciprocal translocation t(9;22)(q34;q11) in chronic myeloid leukemia (CML) patients. In most cases, it is cytogenetically visualized by the Philadelphia (Ph) chromosome. About 5-10% of CML patients lack cytogenetic evidence of the Ph translocation but show BCR/ABL fusion by fluorescence in situ hybridization (FISH) or reverse transcriptase-polymerase chain reaction (RT-PCR). Deletions around the breakpoints on derivative chromosome 9 including 5'ABL and 3'BCR sequences occur in 10-15% of Ph-positive CML patients and are thought to have prognostic significance. METHODS We explored cryptic rearrangements involving chromosomes 9 and 22 in 3 CML patients with an apparently normal bone marrow karyotypes using multiplex RT-PCR and FISH with commercial and home-brew probes. RESULTS The BCR/ABL fusion transcripts were detected by RT-PCR. Using commercial FISH probes, the BCR/ABL fusion gene was found on chromosome 22 in two patients and on chromosome 9 in one patient. Consecutive FISH assays clarified the mechanism of the masked Ph chromosome: in the 3 patients, Ph rearrangement resulted from double mechanism consisting in standard translocation t(9;22)(q34;q11) followed by a second reversed translocation t(9;22)(q34;q11). One patient achieved major cytogenetic response after 6 months of imatinib therapy, and one patient had successful bone marrow transplant. CONCLUSIONS In this study, we have characterized three Ph-negative CML patients with cryptic BCR/ABL rearrangement generated after an uncommon mechanism involving two sequential translocations and confirm that the BCR/ABL hybrid gene may be located on other sites than 22q11. Ph-negative CML patients with BCR/ABL fusion gene have the same prognosis as patients with classical t(9;22).
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MESH Headings
- Adolescent
- Adult
- Chromosome Banding
- Chromosomes, Human, Pair 22/genetics
- Chromosomes, Human, Pair 9/genetics
- Cohort Studies
- Cytogenetics/methods
- Early Detection of Cancer
- Female
- Humans
- In Situ Hybridization, Fluorescence
- Leukemia, Myeloid, Chronic, Atypical, BCR-ABL Negative/genetics
- Male
- Middle Aged
- Philadelphia Chromosome
- Translocation, Genetic
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Affiliation(s)
- Ayda Bennour
- Department of Cytogenetics, Molecular Genetics and Reproductive Biology, Farhat Hached University Teaching Hospital, Sousse, Tunisia.
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Bennour A, Sennana H, Laatiri MA, Khelif A, Saad A. A masked BCR/ABL rearrangement in a case of chronic myeloid leukemia with translocation t(3;9)(p14;q34). ACTA ACUST UNITED AC 2008; 181:72-4. [DOI: 10.1016/j.cancergencyto.2007.11.007] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2007] [Revised: 11/19/2007] [Accepted: 11/20/2007] [Indexed: 10/22/2022]
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Robinson HM, Martineau M, Harris RL, Barber KE, Jalali GR, Moorman AV, Strefford JC, Broadfield ZJ, Cheung KL, Harrison CJ. Derivative chromosome 9 deletions are a significant feature of childhood Philadelphia chromosome positive acute lymphoblastic leukaemia. Leukemia 2005; 19:564-71. [PMID: 15716990 DOI: 10.1038/sj.leu.2403629] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Deletions from the derivative chromosome 9, der(9), of the translocation, t(9;22)(q34;q11), at the site of the ABL/BCR fusion gene, have been demonstrated by fluorescence in situ hybridisation (FISH), in both Philadelphia chromosome (Ph)-positive chronic myeloid leukaemia (CML) and acute lymphoblastic leukaemia (ALL). In CML they occur in 10-15% of cases and appear to indicate a worse prognosis, whereas in ALL, the situation is unclear. This study presents the findings of dual fusion FISH used to detect such deletions in a series of 27 BCR/ ABL-positive childhood ALL patients. Metaphase FISH was essential for the accurate interpretation of interphase FISH signal patterns. Three cases (11%) had a single fusion signal, resulting from deletions of the der(9). Three other patients with variant translocations and one with an insertion, also had a single fusion, but with no evidence of deletions. Gain of a fusion in approximately one-third of patients indicated a second Ph, which appears to be a diagnostic marker of Ph-positive ALL. This study shows that the incidence of deletions from the der(9) in childhood ALL is at least as high as that reported for CML.
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Affiliation(s)
- H M Robinson
- Leukaemia Research Fund Cytogenetics Group, Cancer Sciences Division, University of Southampton, Southampton, UK
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