OBJECTIVETo investigate the value of multiplex fluorescence in situ hybridization (FISH) in the detection of complex karyotypic abnormalities of acute myeloid leukemia (AML).

METHODSMultiplex FISH was used in combination with conventional cytogenetics (CC) and interphase FISH to study 14 cases of AML with complex karyotypic abnormalities.

RESULTSIn the 14 cases of AML studied, conventional cytogenetics detected 23 numerical and 56 structural chromosome abnormalities. Among them 4 gained whole chromosome and 4 lost whole chromosome which were confirmed by multiplex FISH. Twelve chromosome losses detected by CC were revised as derivative chromosomes resulted from various structural aberrations, and 26 derivative and 19 marker chromosomes were characterized precisely by multiplex FISH. Most of them were resulted from unbalanced translocations, including 2 complex 8; 21 translocations, which have not been reported previously: t (8; 21), der (8) t (8; 21) (8pter --> 8q22::21q22 --> 21qter), der (21) t (8; 21; 8) (8qter --> 8q22:: 21p13 --> 21q22::8q22 --> 8qter) and t (21; 8; 18; 1), der (8) t (8; 21) (8pter --> 8q22:: 21q22 --> 21qter), der (21) t (21; 8; 18; 1) (21p13 --> 21q22?::8q22 --> 8q24 ?:: 18??::1q??q??). The complex karyotypic abnormalities involved nearly all chromosomes, of which the chromosomes 17, 7 and 5 were more involved than the rest.

CONCLUSIONMultiplex FISH in combination with conventional cytogenetics may characterize the complex chromosomal abnormalities more precisely. Introduction of this technique to the study of AML with complex chromosomal abnormalities is warranted.