SEGMENTAL JUMPING TRANSLOCATION IN LEUKEMIA AND LYMPHOMA WITH A HIGHLY COMPLEX KARYOTYPE

In order to identify the oncogene associated with malignant transforma tion 141 leukemia and malignant lymphoma patients were studied by FISH . Specific chromosome regions were translocated onto structurally abno rmal chromosomes, resulting in partial tri-, tetra-, or pentasomy of t hese regions. We designated this type of chromosomal translocation as a ''segmental jumping translocation (SJT)''. These SJTs were found in several chromosomal regions such as 8q24, 9q34, 11q13, 11q23, 13q14, 1 4q24-q32, 21q22 and 22q11. The SJT at 9q34, which involved the ABL onc ogene, was found in three of nine secondary leukemia patients who were treated with anticancer drugs and radiation. Non-Hodgkin's lymphoma a nd acute myeloid leukemia (AML) patients had 3-7 copies of SJT at 11q1 3 or 11q23. SJT at 14q32 and 21q22 were predominantly detected in the acute type of adult T-cell leukemia (8 of 27 patients) and in AML (5 o f 17 patients). The size of the SJT regions varied among the patients. The overlapping region within the SJT could involve oncogene(s) assoc iated with transformation to the advanced stage in leukemia and lympho ma patients. The SJT provides evidence of a new mechanism for gene amp lification and formation of unidentified marker chromosomes in the adv anced disease stage.