The philadelphia chromosome and chronic myelogenous leukemia

Sixty of 73 consecutive patients with clinical and laboratory features of chronic myelogenous leukemia had the Philadelphia (Ph¹) chromosome abnormality, as revealed by bone marrow and peripheral blood studies of chromosome morphology. The 13 Ph¹-negative patients differed from the larger Ph¹-positive group by having lower white blood cell and platelet counts and by having a larger proportion of young children under the age of 7. However, the most significant difference was the finding that the Ph¹-negative patients responded poorly to chemotherapy and had a median survival of 18 months as compared to 45 months for the Ph¹-positive population (^P < 0.01). The Ph1 chromosome was observed during all phases of the disease and was unaffected by treatment. In addition to the Ph¹ chromosome, aneuploidy, manifested usually by hyperdiploid Ph¹-positive cell lines, was present in 20 percent of the patients. In 2 patients, 2 Ph¹ chromosomes were seen in the same cell. A single patient with marked aneuploidy had the only chromosome abnormality seen in the 13 Ph¹-negative patients.