[Molecular biology of chronic myeloid leukemia].

Chromosome Philadelphia (Ph) which originated from translocation 9;22 is an aberration connected with chronic myelogenous leukaemia (CML) and with part of the cases of acute lymphoblastic leukaemia (ALL). The analysis on the molecular level has shown that the rearrangement of ABL and BCR genes is the most important consequence of this translocation. The new hybrid gene translates the protein p210, which shows tyrosine phosphokinase activity. This protein could play an important role in the pathogenesis of CML. The investigations of BCR/ABL rearrangement on molecular level are an important tool for differential diagnosis of lymphoblastic crisis of CML and ALL and also are very valuable in detection of residual Ph positive cells in cytogenetic conversion of CML.