OBJECTIVETo explore the value of multiplex fluorescence in situ hybridization (M-FISH) in combination with whole chromosome painting (WCP) in the detection of complex chromosomal aberrations (CCAs) in myelodysplastic syndromes (MDS).

METHODSM-FISH was used in seven MDS patients with R-banding CCAs to refine the complex chromosomal rearrangements, and to identify cryptic translocations and characterization of marker chromosomes. Dual-color WCP procedures were further performed in 7 cases to confirm some rearrangements detected by M-FISH.

RESULTSM-FISH confirmed all results of R-banding. The composition and origin of 6 kinds of marker chromosomes, 9 kinds of chromosomes with additional material undetermined and 5 kinds of derivative chromosomes undefined by conventional cytogenetics (CC) were defined after M-FISH analysis; four kinds of cryptic translocations overlooked by CC were found on derivative chromosomes and previously normal appearing chromosomes. In addition, M-FISH revealed some nonrandom aberrations: aberrations involving chromosome 17 and -5/5q- were the two most frequent aberrations. Some misclassified and missed chromosomal aberrations by M-FISH were corrected by WCP.

CONCLUSIONM-FISH is a powerful molecular cytogenetic tool in clarification of CCAs. Complementary WCP helps us to identify misclassified and missed chromosomal aberrations by M-FISH. CC in combination with molecular cytogenetic techniques, such as M-FISH and WCP, can unravel complex chromosomal aberrations more precisely.