Lavaut SK, Hernández AN

Language: Spanish
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ABSTRACT

Introduction: The t(12;21) (p13;q22) translocation is the most common chromosomal abnormality alteration in pediatric patients with B-cell acute lymphoblastic leukemia (B-ALL), its molecular consequence is the fusion gene ETV6/RUNX1.This translocation is cryptic, so it escapes conventional cytogenetic diagnosis. One of the diagnosis tool is the fluorescence in situ hybridization (FISH) technique.
Objective: To describe hybridization signals patterns observed in pediatric patients with B-ALL.
Methods: Bone marrow samples of 25 pediatric patients with diagnosis of ALL-B were studied at the Cytogenetics Laboratory of the Institute of Hematology and Immunology. LSI ETV6/RUNX1 Dual Color Dual Fusion probe was used.
Results: Eight samples were positive to ETV6/RUNX1 fusion gene, in four of them additional chromosomal alterations were observed: deletion of ETV6 gene allele not translocated, one extra copy of chromosome 21 derivative and extra copies of chromosome 21. Of the 17 negative fusion gene samples, hyperdiploidy was observed in three of them.
Conclusions: The FISH technique was useful for detecting chromosomal abnormalities non visible to karyotype such as t (12;21) and its fusion gene. Also it facilitated the diagnosis of additional chromosomal alterations with prognostic implications.