Comparison of Chromosome Constitution in Chronic Myelocytic Leukemia and Other Myeloproliferative Disorders

The frequency of the Ph¹ chromosome in freshly aspirated marrow cells of 14 patients with typical chronic myelocytic leukemia processed by a "direct technic" without resort to culture or colchicine was significantly higher (> 75 per cent) than that observed in the cultured blood cells (< 35 per cent) of the same subjects. The karyotypic abnormally of the abbreviated G-group chromosome would appear not to be related to therapy, since the frequency with which it occurred was not materially affected by treatment (including radiation). The Ph¹ chromosome was not observed in any of the metaphases of blood or marrow of 12 subjects who had developed a leukemia-like picture complicating either myelofibrosis, polycythemia vera or myeloid metaplasia. A new chromosome abnormality—a shortened D-group chromosome—was observed with about the same frequency in the blood and marrow metaphases of a female patient with treated chronic myelocytic leukemia. This new karyotypic abnormality was associated with the highest frequency of the Ph¹ chromosome in cultured blood cells in the group studied. The Ph¹ chromosome was observed in the metaphases of a patient with the blastic phase of chronic myelocytic leukemia. The variations of the morphology of the Ph¹ chromosome are discussed and illustrated, especially in relation to the Y-chromosome. In four patients with an atypical picture of CML, the Ph¹ chromosome was not observed either in the marrow or cultured blood.