The Role of Cytogenetics in Hematology

By Janet D. Rowley I N 1951, Dameshek’ coined the term “myeloproliferative syndromes” to identify a group of hematologic disorders characterized by proliferation of one or more of the cell types that occur in the bone marrow. This concept provided a unifying hypothesis which has proved useful in the analysis of the similarities and differences between the various disorders. A particularly valuable part of Dameshek’s concept was the provision for the observed transitions and overlaps between the different myeloproliferative states. Besides undergoing such transitions, the subgroups polycythemia rubra vera (PV), essential thrombocythemia, chronic myelogenous leukemia (CML), and myelosclerosis with myeloid metaplasia (MMM) could terminate, with differing frequencies, in acute myelogenous leukemia (AM L). Chromosome analysis of bone marrow cells by use of the recent techniques of quinacrine fluorescence and Giemsa banding has provided new perspectives about the relationship of these diseases to each other and to a number of other hematologic disorders, such as the refractory anemias and acute leukemia. My purpose here is to inform hematologists regarding three important contributions that can be made by cytogenetic analysis of bone marrow cells. First, in some ill-defined disorders such as the refractory anemias, the presence of a particular abnormal chromosomal pattern may identify a specific subset of patients.2 Second, the presence of an abnormal karyotype in a patient with other signs suggestive of acute leukemia allows the clinician to make the diagnosis earlier and therefore to start treatment sooner than if the karyotype had not been determined.3’4 Finally, in chronic myelogenous leukemia,5 and probably also in some types of acute leukemia,6 the karyotype provides a valuable prognostic indicator of the patient’s response to treatment and of the clinical course.