FREQUENT JUMPING TRANSLOCATIONS OF CHROMOSOMAL SEGMENTS INVOLVING THEABL ONCOGENE ALONE OR IN COMBINATION WITH CD3-MLL GENES IN SECONDARY LEUKEMIAS

Seven secondary leukemia patients were treated for solid tumors or mal ignant lymphoma with anticancer drugs or radiation. We studied bone ma rrow samples from these patients by fluorescence in situ hybridization (FISH). Of the seven patients, three had increased signals for the AB L oncogene (9q34) on interphase nuclei and at metaphase. One of the th ree patients also had four signals for the CD3 (MLL) region (11q23). W hole painting probes revealed that these chromosomal regions were tran slocated onto structurally abnormal chromosomes, resulting in partial tri-, tetra- or penta-somy of these regions. We called this type of tr anslocation ''segmental jumping translocation (SJT).'' SJT of the ABL oncogene was not detected in samples from 15 patients with de novo acu te myelocytic leukemia (AML), 12 with myelodysplastic syndrome (MDS), or 20 with chronic myelocytic leukemia (CML) at the chronic phase. Fur thermore, monosomy 7 was also found in the patients with the gene ampl ification. These results indicate that SJT of ABL and/or CD3 (MLL) gen es is associated with the leukemogenesis of secondary leukemia. The SJ T may be one mechanism of gene amplification. (C) 1997 by The American Society of Hematology.