Fluorescence in Situ Hybridization (FISH) Is a Reliable Diagnostic Tool for Detection of the 9; 22 Translocation

Abstract

The fluorescence in situ hybridization (FISH) technique for detection of the 9;22 translocation was compared with the "gold standard" of conventional cytogenetics. For this purpose, both methods were applied to 81 bone marrow aspirates and/or peripheral blood specimens comprising 50 CML cases and controls from 31 patients without CML. Independently, core biopsies of these 81 patients were investigated by three histopathologists. Conventional karyotype analysis from unstimulated bone marrow cells was successful in 71/81 cases and demonstrated the Ph-chromosome in 42/46 CML patients. With FISH, results were obtained in all 81 cases investigated, confirming fusion of the ber and abl genes in all cytogenetically Ph-positive patients. Among the five Ph-chromosome-negative specimens bcr/abl fusions were detected in only one patient. The percentage of cells found to be Ph-positive by both methods was correlated, but in individual cases considerable differences in the numbers of Ph-positive cells were observed. Different results may be due to selection of cells after in vitro cultivation predominantly. FISH proved to be a very reliable technique for specimens that do not contain dividing cells. With FISH, large numbers of cells can easily be scored which is an advantage compared to conventional cytogenetics. Therefore, this method is particularly suitable for those whose therapy is being monitored or a relapse is suspected. However, the FISH results should be evaluated critically with respect to the practical limit of sensitivity since non-specific fusion signals can also be observed in a small percentage of cells in non-CML cases. It is suggested that each laboratory define its own threshold of bcr/abl fusion signals for diagnosing Ph-positive CML by FISH.

FISH for BCR-ABL on interphases of peripheral blood neutrophils but not of unselected white cells correlates with bone marrow cytogenetics in CML patients treated with imatinib

“…This approach has been used in several studies in patients on nonimatinib treatment. 12,[20][21][22] However, the correction led only to a very moderate improvement of the correlation coefficient to 0.6817 (P ¼ 0.005).…”

High rate of chromosome abnormalities detected by fluorescence in situ hybridization using BCR and ABL probes in adult acute lymphoblastic leukemia

“…20 The high value of FISH analysis with ABL and BCR probes in the initial diagnosis and for the detection of residual disease in CML patients has been demonstrated in several studies. [14][15][16][21][22][23][24][25][26][27][28] In ALL, the applicability of FISH to detect the BCR/ABL rearrangement has only been addressed in small series of selected patients and in single cases with variant Ph translocations. 15,16,20,29,30 Using FISH on interphase nuclei, a colocalization of a BCR and ABL hybridization spot may occur by chance due to the two-dimensional projection of the BCR and ABL hybridization signals of the three-dimensional nucleus, and thus lead to a false positive result.…”

A Comparative Analysis of FISH, RT-PCR, and Cytogenetics for the Diagnosis ofbcr-ablPositive Leukemias

“…[22][23][24][25] Furthermore, the detection of bcr rearrangements by Southern blot analysis is problematic if the minor break-point region is involved. 26 Recently, double-color fluorescence in situ hybridization (FISH) has been used for the identification of gene fusion, [27][28][29][30][31][32][33][34] but systematic data testing and comparing this approach with cytogenetics and RT-PCR are needed, and, to date, FISH is not used routinely as a diagnostic method for identifying the bcr-abl translocation.…”