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Updated: Aug 10, 2026
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FISH for Pre-implantation Genetic Diagnosis
Published on: February 24, 2011
Monosomy 20 as a pointer to dicentric (9;20) in acute lymphoblastic leukemia
R Clark1, S A Byatt, C F Bennett
1Leukaemia Research Fund/United Kingdom Cancer Cytogenetics Group Karyotype Database in Acute Lymphoblastic Leukaemia, Department of Haematology, Royal Free and University College Medical School, London, UK.
Leukemia
|February 16, 2000
Summary
The dicentric chromosome dic(9;20) in acute lymphoblastic leukemia (ALL) is often misidentified as monosomy 20. Fluorescence in situ hybridization (FISH) is crucial for accurate diagnosis of this rare abnormality.
Area of Science:
- Hematology
- Cytogenetics
- Oncology
Background:
- Acute lymphoblastic leukemia (ALL) is a heterogeneous hematologic malignancy.
- The dicentric chromosome dic(9;20)(p1113;q11) is a rare chromosomal abnormality observed in ALL.
- Standard G-banding techniques can misinterpret dic(9;20) as monosomy 20, hindering accurate diagnosis.
Purpose of the Study:
- To identify and characterize new cases of ALL with the dic(9;20) chromosomal abnormality.
- To evaluate the diagnostic utility of fluorescence in situ hybridization (FISH) for detecting dic(9;20).
- To investigate the clinical and cytogenetic associations of dic(9;20) in ALL patients.
Main Methods:
- Retrospective analysis of 20 new cases of ALL with suspected dic(9;20).
- G-banding and fluorescence in situ hybridization (FISH) were used for chromosomal analysis.
- Review of the Leukaemia Research Fund/UK Cancer Cytogenetics Group Karyotype Database for cases with monosomy 20.
Main Results:
- Twenty new cases of ALL with dic(9;20) were identified, increasing the total reported cases to 37.
- FISH confirmed dic(9;20) in 20 out of 25 cases initially suspected of having monosomy 20.
- Eight of the 20 patients with dic(9;20) also exhibited trisomy 21. One case of T-ALL with dic(9;20) was identified.
Conclusions:
- The dicentric chromosome dic(9;20) is an under-recognized abnormality in ALL that requires FISH for accurate identification.
- dic(9;20) is associated with specific immunophenotypes and can co-occur with trisomy 21.
- Accurate cytogenetic diagnosis of dic(9;20) is essential for understanding its role in ALL pathogenesis and prognosis.
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