OBJECTIVE: To compare the results of fluorescence in situ hybridization (FISH) 
versus conventional cytogenetics (CC) in the detection of common chromosomal 
abnormalities and evaluate the significance of FISH in myelodysplastic syndrome 
(MDS) .
METHODS: A total of 344 patients with de novo MDS from June 2008 to October 2012 
were detected by 6 pairs of probes, including CSF1R/D5S23-D5S721 (5q33) , EGR1/ 
D5S23-D5S721 (5q31) , D7S486 (7q31) /CSP7, D7S522 (7q31) /CSP7, D20S108/CSP8 
(20q12/CSP8) and CSPX/CSPY. The results were compared with those of CC.
RESULTS: CC revealed cytogenetic abnormalities in 168/344 cases (48.8%) and the 
frequency of common aberrations such as +8, 20q-, -7/7q-, -5/5q- and -Y were 
18.9% (65/344) , 9.3% (32/344), 8.4% (29/344), 8.4% (29/344) and 2.4% (5/206) 
respectively. While FISH revealed chromosome abnormalities in 147/344 patients 
(42.7%) and the frequency of +8, 20q-, -7/7q-, -5/5q- and -Y were 20.9% 
(72/344), 11.6% (40/344), 11.6% (40/344), 10.2% (35/344) and 2.9% (6/206) 
respectively. Overall 187/344 patients (54.4%) carried clonal aberrations by a 
combination of CC and FISH. Among 158 patients with normal karyotype by CC, 14 
cases (8.9%) were detected to have clonal aberrations by FISH. FISH also 
confirmed 4 carriers of clonal aberrations out of 9 patients with non clonal 
abnormalities by CC.
CONCLUSIONS: FISH is effective for improving the probability of detecting 
chromosome abnormalities in MDS cases with normal karyotypes and karyotype 
failure. FISH may provide rationales for clonal abnormalities in patients with 
non clonal aberrations by CC. A combination of FISH and CC shows complementary 
advantages.