INVESTIGATION OF CHROMOSOMAL ABNORMALITIES INVOLVING CHROMOSOMES 12 AND 21 IN CHILDHOOD ACUTE LYMPHOBLASTIC LEUKEMIA BY KARYOTYPING AND FLUORESCENCE IN SITU HYBRIDIZATION (FISH)
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Abstract
Objective: This study aimed to investigate chromosomal abnormalities involving chromosomes 12 and 21 in childhood acute lymphoblastic leukemia (ALL) using karyotyping and fluorescence in situ hybridization (FISH).
Study design: A retrospective cross-sectional case series.
Study setting and period: The study was conducted at the Blood Transfusion and Hematology Hospital from January 2023 to December 2025.
Study population: Pediatric patients (<16 years of age) diagnosed with acute lymphoblastic leukemia (ALL) based on bone marrow examination and immunophenotyping by flow cytometry. Peripheral blood and/or bone marrow samples were analyzed for abnormalities involving chromosome regions 12p13 and 21q22 using conventional cytogenetic analysis (karyotyping) and fluorescence in situ hybridization (FISH).
Results: Among a total of 184 pediatric ALL cases analyzed, chromosomal abnormalities were detected in 85 cases (46.2%) by karyotyping, whereas FISH identified abnormalities involving chromosomes 12 and 21 in 106 cases (57.6%). Among 99 cases (53.8%) with normal karyotypes, 28 cases showed abnormalities of chromosomes 12 and 21 by FISH. Specifically, 15 cases (15.1%) exhibited numerical signal abnormalities at 12p13 and 21q22, including 14 cases (14.1%) with signal amplification of 12p13 and/or 21q22 and 1 case (1.0%) with deletion of 12p13. Additionally, 13 cases (13.1%) showed the translocation t(12;21)(p13;q22), as detected by FISH. Among 78 cases (42.8%) with no detectable abnormalities at 12p13 and 21q22 by FISH, 6 cases (7.7%) had abnormalities involving other chromosomes, and 1 case (1.3%) showed abnormalities related to chromosomes 12 and 21 but not at loci 12p13 or 21q22.
Conclusion: The findings indicate that both karyotyping and FISH have distinct advantages and certain limitations in detecting chromosomal abnormalities. Therefore, the combined use of karyotyping and FISH—two complementary techniques—is essential to avoid missed abnormalities and has significant value in supporting the diagnosis of childhood ALL.
Keywords
Pediatric Acute lymphoblastic leukemia, chromosomal abnormalities of chromosomes 12 and 21, karyotype, FISH
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References
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