OBJECTIVETo explore the value of multiplex fluorescence in situ hybridization (M-FISH) technique in the detection of the complex chromosomal aberrations (CCAs) and marker chromosomes in acute leukemia (AL).

METHODSM-FISH was performed in 11 AL patients with R-banding CCAs or marker chromosomes to define the unrecognized chromosomal aberrations and the constitution of marker chromosomes, and to identify small and cryptic translocations.

RESULTSIn the 11 AL cases studied, 27 numerical and 41 structural chromosomal abnormalities were detected by conventional cytogenetics (CC), among which 3 chromosomal gains and 9 chromosomal losses as well as 12 structural abnormalities were confirmed by M-FISH, and another 15 chromosomal losses were revised by M-FISH as derivative chromosomes. M-FISH detected 3 additional chromosomal gains that were undetected by CC. The other 29 structural abnormalities including 17 marker chromosomes were characterized by M-FISH. A total of 33 structural abnormalities were detected by M-FISH, in which 6 were unreported before, i.e. t(5q-;16)(? q14;q24), der(9)(Y::9::Y::9), der(7) (7::8::9), ins(20;21), der(11) (11::21::20) and der(3)t(3p-;13)(3p-;q21), most of which resulted from unbalanced translocations. Almost all chromosomes were involved in CCAs, the more common ones were chromosome 17, 5, 7, 15, 11 in AML and 8, 9, 14, 22 in ALL.

CONCLUSIONCombining M-FISH with CC can raise resolution of the latter, which justifies its clinical application for the detection of CCAs and marker chromosomes.