Application of Metaphase-Fluorescence in Situ Hybridization to the Diagnosis of Acute Promyelocytic Leukemia and the Detection of Minimal Residual Disease / 中国实验血液学杂志

ABSTRACT

To investigate the value of metaphase-fluorescence in situ hybridization (M-FISH) in the diagnosis of acute promyelocytic leukemia (APL) and the detection of its minimal residual disease (MRD), 10 cases of untreated acute myeloid leukemia (AML) (de novo APL 5 cases, relapsed APL 3 cases, AML-M(1) and AML-M(5) one case each) diagnosis by cell morphology at presentation and 10 cases of APL after complete remission (CR) were studied by M-FISH using a whole chromosome 17 painting probe labeled by digoxigenin and the results were compared with that of conventional cytogenetic examination and reverse transcription-polymerase chain reaction (RT-PCR). Among 10 untreated AML cases, 7 had positive M-FISH results, of whom 4 had t (15;17) translocation, 3 had normal karyotype. Six of them had PML/RARalpha fusion transcript except one, in whom RT-PCR did not be performed; 3 had negative M-FISH results, of whom one had del (2q) x 2 abnormalities, who was RT-PCR-positive for PML/RARalpha fusion transcript; one had complex karyotype abnormalities, whose RT-PCR was negative for PML/RARalpha fusion transcript; one had t (9;22) translocation, whose RT-PCR was negative for PML/RARalpha fusion transcript, but positive for BCR/ABL fusion transcript. Thus the diagnosis of AML-M(3) was revised as AML-M(2) for the latter two cases. 10 APL cases after CR had normal karyotype, but 12/15 M-FISH assays detected 1 - 5 t (15;17) positive cells in 9 of them. This finding is compatible with the results of RT-PCR assays. Leukemia relapse was seen in one case, and two positive M-FISH results were appeared in the 2 assays at a 13 months' interval. This study suggests that M-FISH had important practical value in the diagnosis of APL and the detection of MRD, and that it is less sensitive than RT-PCR, however, it seems to be more potential for prediction of the relapse of leukemia due to its capacity of detecting quantitatively the chromosome translocation in proliferative cells.