Missing Y chromosome in 2 patients with chronic myelocytic leukemia

2 cases of chronic myelocytic leukemia (CML) without Y chromosome are reported. One is a 45-year-old man with Philadelphia-positive CML, and the other a 74-year-old patient with Philadelphia-negative CML. Cytogenetic analysis of bone marrow and peripheral blood cultures with and without PHA stimulation was carried out. The Philadelphia-positive patient died after 15 months, whereas in the case of the Philadelphia-negative patient, the survival time of 27 months exceeded the median survival time usually reported for Philadelphia-negative CML patients, thus indicating a prognostic relevance of the missing Y chromosome.