FLUORESCENCE IN-SITU HYBRIDIZATION ANALYSIS OF T(3-12)(Q26-P13) - A RECURRING CHROMOSOMAL ABNORMALITY INVOLVING THE TEL GENE (ETV6) IN MYELODYSPLASTIC-SYNDROMES

We have identified a new recurrent reciprocal translocation between ch romosome 3 and 12, with breakpoints at bands 3q26 and 12p13, t(3;12)(q 26;p13) in the malignant cells from five patients with acute transform ation of myelodysplastic syndrome or blast crisis of chronic myelogeno us leukemia. t(3;12)(q26;p13) appears as a rare but nonrandom event pr esent in various myeloid leukemia subtypes,which is frequently associa ted with dysplasia of megakaryocytes, multilineage involvement, short duration of any blastic phase, and a very poor prognosis. Here, we rep ort the molecular cytogenetic analysis of the t(3;12). Fluorescence in situ hybridization results indicate that the 3q26 breakpoints are qui te heterogeneous and occur 5' of MDS1 3' of EVI1, or between MDS1 and EVI1. Our results are very similar to those observed in other 3q26 rea rrangements in which breakpoints were shown to occur over considerable distances 5' and 3' of EVI1. Fluorescence in situ hybridization inves tigations proved that, in three myelodysplastic syndrome cases with t( 3:12)(q26;p13), the 12p13 breakpoint occurred within the TEL gene. (C) 1996 by The American Society of Hematology.