Clinical, cytogenetic and dual-color FISH studies on five cases of myelodysplastic syndrome or acute myeloid leukemia patients with 1;7 translocation

OBJECTIVE: To study the clinical and cytogenetic characteristics of four patients with myelodysplastic syndrome (MDS) and one with acute myeloid leukemia experiencing t (1;7). METHODS: Five patients seen in our hospital from 1992 to 2001 were diagnosed as MDS and acute myelocytic leukemia (AML) according to the French-American-British (FAB) criteria. Chromosomes were prepared using the direct method as well as 24-hour unstimulated cultures of fresh heparinized bone marrow for each subject, while R-banding was used to analyze karyotypes. Dual-color fluorescence in situ hybridization (FISH) using SpectrumRed and SpectrumGreen directly labeled chromosome 1-specific alpha-satellite DNA probe (red) and chromosome 7- specific alpha-satellite DNA probe (green) was performed for three cases. RESULTS: Of the five patients, three had 1;7 translocation due to a long history of exposure to benzene. In three cases, dual-color FISH resulted in three red signals and two green ones, in which one red signal adjoining one green signal in 27.6%, 84% and 18.5% metaphases, respectively. CONCLUSIONS: Exposure to benzene may be the cause for Chinese MDS and AML patients with t (1;7) translocation. The result of dual-color FISH convincingly confirmed that the centromere of the derivative chromosome 7p/1q resulting from 1;7 translocation was made up of centromeres from both chromosomes 1 and 7.