[c-myc gene amplification and N-ras transforming gene in two cases of acute myelocytic leukemia with double minute chromosomes].

We report two leukemia patients with double minutes (DMs) chromosomes. Both patients were diagnosed as having acute myelocytic leukemia (AML) FAB M2. Cytogenetic analysis showed normal chromosome karyotype with 1-53 DMs chromosomes in the first patient, and complex chromosome aberrations including deletion of chromosome 8 at 8q24 region and 1-84 DMs chromosomes in the second patient who had a history of extensive radiotherapy for laryngeal cancer 8 years prior to the development of leukemia. Analysis of DNA from the two patients revealed that oncogene of c-myc was amplified about 5 to 10 folds in the leukemic cells. The other fourteen oncogene of c-myc was c-myb, c-abl and N-myc, showed no increases of gene content. Furthermore, a transforming gene, N-ras was detected in the first patient by in vivo selection assay method. This is the second report on AML patients with c-myc gene amplification and DMs chromosomes.