Characterization of Complex Chromosomal Rearrangements in Acute Myeloid Leukemia: FISH and Multicolor FISH Add Precision in Defining Abnormalities Associated with Poor Prognosis

Introduction: The identification of specific chromosome abnormalities in Acute Myeloid Leukemia (AML) is the important for the stratification of patients into the appropriate treatment protocols. However, a significant proportion of diagnostic bone marrow karyotype in AML is reported as normal by conventional cytogenetic analysis. It is suspected that this karyotype may conceal the presence of diagnostically significant chromosome rearrangements. Complex chromosomal aberrations can be detected in a substantial proportion of AML, which are associated with very poor prognosis. Conventional cytogenetic analysis cannot accurately define the specific alterations in Complex chromosomal aberrations. M-FISH allows the comprehensive identification of complex chromosomal aberrations.

Materials and Methods: To address this question, in a series of 321 AML patients, 9 patients showed complex karyotype. Fluorescence In situ Hybridization (FISH) and Multicolor FISH (M-FISH) assay were carried out in 4 patients.

Results: Several rare, novel and recurrent translocations were identified with conventional cytogenetic and molecular cytogenetic techniques. M-FISH analysis identified cryptic chromosomal rearrangements by Conventional cytogenetic analysis.

Conclusion: Present study revealed that M-FISH is a powerful molecular cytogenetic tool to characterize complex karyotype in AML.