Double minute chromosomes contain amplified c-myc oncogene sequences in acute myeloid leukemia

We describe two elderly male patients with acute myeloid leukemia transformed from myelodysplastic bone marrow. Neither patients had a history of prior exposure to mutagenic agents or other malignancies. Chromosome analysis at the time of initial diagnosis revealed 47,XY,del(5)(q14q33),+21 in patient 1 and 45,XY,add(1)(q23),-5,del(8)(p11.2p23),der(17)t(5;17)(p12;p11.2) in patient 2. In addition, numerous copies of double minute chromosomes were seen in both patients. We used fluorescence in situ hybridization to identify the amplified sequences presumed to represent the dmins in the leukemic cells. In both cases, it appeared that the dmins were derived from specific amplification of c-myc oncogene.