OBJECTIVETo investigate the utilities of dual-color fluorescence in situ hybridization (FISH) in diagnosis and monitor of treatment in acute myeloid leukemia (AML) with t (8; 21).

METHODSSeventy patients having FISH results were divided into two groups: untreated and treated group. Comparative analysis was performed between the results of conventional cytogenetic analysis (CCA) and FISH analysis, and in some of them, between FISH and reverse transcriptase polymerase chain reaction (RT-PCR) results. A successive FISH following R-banding was carried out in those with cytogenetic undetermined cases.

RESULTSIn untreated group, 30/42 cases of t (8; 21) AML were positive for AML1/ETO in FISH assay. Three cases were positive for AML/ETO by FISH although two of them lacked t (8; 21) by CCA and one negative for AML1/ETO by RT-PCR. Six cases with complex karyotype abnormalities were confirmed to be AML1/ETO positive by the successive R-banding and FISH assay, and the involved genes were clearly visualized in FISH image. In the treated group, there were 28 cases of t (8; 21) AML diagnosed. Three cases without t (8; 21) by CCA were positive by FISH. Two patients were detected relapse earlier by FISH.

CONCLUSIONThe dual-color FISH technique is a much more sensitive and accurate approach to the diagnosis of t (8; 21) AML and minimal residual disease (MRD) monitoring. It can also provide precise mapping of fusion signals in complex karyotype.