Blast crisis of Philadelphia chromosome-positive chronic myeloid leukaemia carrying micro-bcr breakpoint (e19a2 and e191a).

We describe two Philadelphia chromosome-positive chronic myeloid leukaemia (Ph-positive CML) patients carrying micro-bcr (micro-bcr) breakpoint, who developed blast crisis within 5 years of diagnosis. Reverse transcription polymerase chain reaction analysis of bone marrow cells using primers specific for the p210BCR-ABL fusion transcript showed aberrant large-sized bands in both cases (986 bp in patient 1 and 1031 bp in patient 2). Sequencing analysis of these products revealed BCR-ABL fusion transcripts with e19a2 in patient 1 and e191a in patient 2. These findings suggest that CML carrying micro-bcr breakpoint may exhibit a similar clinical course to classical CML, and that it may not be a mild form of the disease.