Chronic myelogeneous leukemia is a proliferative disease of the hematopoietic system. It is characterized by clonal expansion of a primitive pluripotent stem cell that has the capacity to differentiate into the myeloid, monocyte, megakaryocyte and erythrocyte lineage, B and T cells. Under normal physiological hematopoietic conditions there is a balance between proliferation and differentiation. On the other hand, the population of hematopoietic stem cells must also undergo a self renewal process. In chronic myelogeneous leukemia stem cells, unregulated proliferation is associated with the 210kDa tyrosine kinase, which is the product of the BCR/ABL fusion gene, in the translocation involving chromosomes 9 and 22, a karyotype marker of chronic myelogeneous leukemia. Several chimeric transcripts have been described and it has been observed that the seriousness of the clinical picture depend on the generated mRNA. In the present work we analyzed 28 samples of bone marrow cells from 27 patients diagnosed with chronic myelogeneous leukemia. In all samples the translocation t(9;22) was present and they were analyzed for the presence of the fusion transcripts (b3a2 or b2a2) using RT-PCR and Nested- PCR, techniques that were shown to be more sensitive for the identification of these transcripts. Among the patients, 12% presented fusion b3a2, 18% showed b2a2 fusion transcript and 32% both types, b3a2 and b2a2. The presence of the transcript, b3a2, seems to be related with a platelet above 10 ³ X 10 ³/mm³, recognized as a worse prognostic chracteristic in patients with chronic myelogeneous leukemia.
Chronic myeloid leukemia; citogenetics
