Study of BCR-ABL gene rearrangement by dual-color-dual-fusion fluorescence in situ hybridization on acute lymphoblastic leukemia patients

Objective To explore the value of dual-color-dual-fusion fluorescence in situ hybridization (DC-DF-FISH) for the detection of BCR-ABL gene rearrangement in acute lymphoblastic leukemia(ALL).Methods Twenty-six cases of ALL were detected by conventional cytogenetics(CCG), DC-DF-FISH, reverse transcriptase polymerase chain reaction (RT-PCR) and flow cytometry(FACs) for Ph chromosome, BCR-ABL fusion gene and immunophenotype.Results All cases that were detected Ph chromosome or BCR-ABL positive were B cell ALL or acute biphenotypic leukemia (BAL) in 26 cases by FACs. The Philadelphia chromosome (Ph chromosome) was detected in 3 cases (positive percent was 11.5%) by CCG, and BCR-ABL fusion gene also was identified in the 3 cases by DC-DF-FISH and RT-PCR, so Philadelphia chromosome positive ALL (Ph~+ALL) was diagnosed. However, out of 23 cases whose t(9;22) was not detected by CCG, 6 cases were identified having BCR-ABL fusion gene by DC-DF-FISH and RT-PCR, thus, these cases were considered having cryptic t(9;22). The positive percent was 34.6% by DC-DF-FISH and RT-PCR.Conclusions The DC-DF-FISH is an accurate and reliable method for the detection of BCR-ABL rearrangement and it is applicable for the diagnosis, treatment evaluation and the detection of minimal residual disease (MRD) in ALL.