OBJECTIVETo explore the value of dual-color fluorescence in situ hybridization (D-FISH) in the detection of inv(16) in acute myeloid leukemia (AML).

METHODSEleven AML patients were investigated by D-FISH with two-color break apart probe for MYH11 labeled directly by fluorescein isocyanate (FITC) and a Texas Red. The results were associated or compared with those of cell morphology, cytogenetics, single color fluorescence in situ hybridization (FISH) and reverse transcription-polymerase chain reaction (RT-PCR).

RESULTSFour cases (M4Eo three cases, M2a one case) had inv(16), of which one had trisomy 22 in addition to inv(16), while the other seven cases had no inv(16), of which, five cases (M4Eo three cases, M4 two cases)had a normal karyotype, one (M2a) had 5p+ and trisomy 22, one (M4Eo) had a translocation t(9;22) on G-banded karyotypic analysis. All 11 cases of AML were positive for the rearrangement of inv(16) detected by D-FISH. The average positive cell rate for these 11 AML patients was 93.45% (range 86.6%-98.7%). Of them, four had a minimal deletion of 16p13 in addition to inv(16). The results of D-FISH coincided with those of RT-PCR or single color FISH.

CONCLUSIOND-FISH is a powerful tool for the detection of inv(16) due to its sensitivity and specificity. For raising the detecting rate of inv(16), it is necessary to screen inv(16) rearrangement by D-FISH in all M4- and M2-AML cases or the cases with trisomy 22, no matter whether they are accompanied by bone marrow eosinophilia.