Clonal evolution of karyotype in blastic phase of CML.

A patient with chronic myelocytic leukemia (CML) had a Philadelphia chromosome--Ph1(t(9q +; 22q--)) in all evaluated bone marrow cells at the time of diagnosis. After 29 months of intermittent therapy (chemotherapy and immunotherapy) and 2 months before clinical signs of blastic phase developed, three additional cell lines in bone marrow and peripheral blood appeared: one line with extra chromosome Ph1, another one in which chromosome Y disappeared, and the third line with extra chromosome No. 13, evidently derived from the X-monosomie cell line. Five weeks before death a variable hypodiploidy was found in more than 50% mitoses. The patient died 47 months after the establishment of CML and seven months after the onset of the blastic phase.