Philadelphia chromosome in chronic myelogenous leukemia: confirmation of cytogenetic diagnosis in Ph positive and negative cases by fluorescence in situ hybridization

Recurrent duplication of Xq27∼qter in hematological malignancies revealed by multicolor fluorescence in situ hybridization and multicolor banding

Multicolor fluorescence in situ hybridization (M-FISH) experiments were performed to determine the composition of abnormal complex karyotypes in 15 cases of hematological malignancy. Four cases were found to have unsuspected unbalanced X chromosome translocations, which resulted in the presence of extra X chromosome material. We determined the identity of the duplicated chromosome regions using the multicolor banding (mBAND) technique. Xq27-qter was duplicated in three of the four male cases with an X chromosome abnormality (i.e., in one third of male cases and one fifth of all cases). These preliminary results may point to the existence of a recurrent chromosome abnormality, either translocation at a specific Xq27 locus or duplication of Xq27-qter.

Fluorescent in-situ hybridization (FISH) for BCR/ABL in chronic myeloid leukemia after bone marrow transplantation

CONTEXT

Identification of Philadelphia chromosome or BCR/ABL gene rearrangement in chronic myeloid leukemia is important at diagnosis as well as after treatment.

OBJECTIVE

To compare the results of karyotyping using fluorescent in-situ hybridization (FISH) upon diagnosis and 1 year after bone marrow transplantation in 12 patients.

TYPE OF STUDY

Diagnostic test and residual disease detection.

SETTING

Hematology and Hemotherapy Department, Federal University of São Paulo/Escola Paulista de Medicina, São Paulo, Brazil.

SAMPLE

12 patients with chronic myeloid leukemia at diagnosis and 1 year after bone marrow transplantation.

DIAGNOSTIC TEST

Karyotyping was done in the usual way and the BCR/ABL gene-specific probe was used for FISH.

MAIN MEASUREMENTS

Disease at diagnosis and residual.

RESULTS

At diagnosis, 10 patients presented t(9;22)(q34.1;q11) as well as positive FISH. Two cases did not have metaphases but FISH was positive. After bone marrow transplantation, 8 patients presented normal karyotype, 1 had persistence of identifiable Philadelphia chromosome and 3 had no metaphases. Two cases showed complete chimera and 2 had donor and host cells simultaneously. FISH was possible in all cases after bone marrow transplantation and confirmed the persistence of identifiable Philadelphia chromosome clone in one patient, and identified another that did not present metaphases for analysis. Cases that showed mixed chimera in karyotype were negative for BCR/ABL by FISH.

CONCLUSION

The applicability of FISH is clear, particularly for residual disease detection. Classical and molecular cytogenetics are complementary methods.

Paediatric myelodysplastic syndrome (MDS) and juvenile chronic myelogenous leukaemia (JCML) detected by cytogenetic and FISH techniques

This report presents two rare cases, one of paediatric myelodysplastic syndrome (MDS) and the other juvenile chronic myeloid leukaemia (jCML). In the first case, there were clinical and biological features of MDS-refractory anaemia with excess blasts (RAEB). The bone marrow (BM) karyotype demonstrated a monosomy 7 which was confirmed by fluorescence in situ hybridization (FISH). In addition, FISH analysis showed that an alpha-satellite DNA sequence had been transferred from chromosomes 13/21 to one homologue of chromosomes 22. The BCR-ABL rearrangement was negative. In the second case, at diagnosis, the karyotype was 46,XX. FISH analysis with the simultaneous and individual application of abl and bcr probes for chromosome 9 and 22, respectively, revealed the presence of the BCR-ABL rearrangement in addition to an extra ABL sequence locating chromosome 20. A clone that was BCR-ABL gene rearrangement negative but with an extra ABL DNA sequence on chromsome 20, and another clone that was BCR-ABL gene rearrangement negative were detected by DC-FISH and uni-colour (UC-) FISH analysis. No monosomy 7 was detected by conventional cytogenetic or FISH analyses.

Clinical implications of fluorescence in situ hybridization analysis in 13 chronic myeloid leukemia cases: Ph-negative and variant Ph-positive

Thirteen chronic myeloid leukemia (CML) patients, 10 with variant Philadelphia (Ph) translocations and 3 Ph negative cases, were analyzed by fluorescence in situ hybridization (FISH) with the use of BCR and ABL cosmid probes and a chromosome 22 painting probe. In the variant Ph translocations, the BCR-ABL fusion gene was located on the Ph chromosome; in 1 CML Ph-negative patient, the BCR-ABL fusion gene was located on the Ph chromosome; and, in 2 patients, it was located on chromosome 9. The chromosome 22 painting probe was detected on the third-party chromosome of the variant translocation, and in none of the variant translocations was there any detectable signal on chromosome 9. In CML patients with clonal evolution of a simple Ph, a signal of the chromosome 22 painting probe was detected on the der(9) of the Ph translocation. It was concluded that the variant Ph translocations evolved simultaneously in a three-way rearrangement. The clinical parameters of the 13 patients were similar to those of a large group of CML patients with a simple Ph translocation. It is suggested that, to determine the prognosis of CML patients with a complex karyotype, FISH analysis with a chromosome 22 painting probe be performed.