Heterogeneity of breakpoint cluster region-abelson [BCR-ABL] rearrangement in patients with chronic myeloid leukemia

ABSTRACT

Breakpoint cluster region-Abelson [BCR-ABL] rearrangement or Philadelphia [Ph] chromosome in Chronic Myeloid Leukemia [CML] is derived from a reciprocal chromosomal translocation between ABL gene on chromosome 9 and BCR gene on chromosome 22. This chimeric protein has various sizes and therefore different clinical behaviour. The purpose of this study was to determine the heterogeneity of BCR-ABL rearrangement in patients with Ph+CML in Pakistan. The study was conducted at Civil Hospital and Baqai Institute of Hematology [BIH] Karachi. Blood samples from 25 patients with CML were collected. Multiplex reverse transcription polymerase chain reaction [RT-PCR] was performed to identify various BCR-ABL transcripts. All 25 samples showed BCR-ABL rearrangements. Out of these, 24 [96%] patients expressed p210 BCR-ABL rearrangements i.e. 60% [n=15] had b3a2 and 32% [n=8] had b2a2 rearrangements. Co-expression of b3a2 /b2a2 rearrangement and p190 [e1a3] rearrangement was also identified in two patients. It is apparent that majority of the patients had p210 BCR-ABL rearrangements. Frequency of co-expression and rare fusion transcripts was very low