Detection of c-myc oncogene amplification in a CML blastic phase patient with double minute chromosomes.

Double minute chromosomes (dmin) are relatively rare in leukemias. Cytogenetic analysis of blood cells from a woman with blastic phase chronic myelogenous leukemia (BC-CML) showed numerous dmin chromosomes and complex abnormalities including a Philadelphia (ph(1))-chromosome. Oncogene amplification in hematopoietic malignancies is also rare. Using PCR, we retrospectively investigated the extent of c-myc gene amplification in DNA extracted from stored blood smears from the patient. To qualify the PCR products, the beta-globin gene was used as the internal reference gene and it was co-amplified with the c-myc gene. The extent of amplified c-myc was about 6.8-fold. This finding suggests that the c-myc gene was amplified in dmin and that the gene amplification contributes to the progression to acute leukemia or rapid growth of leukemic cells.