Heterogeneity of Breakpoint Cluster Region-Abelson (BCR-ABL) rearrangement in patients with chronic myeloid leukemia

Background and objective: 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. methods: 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. results: 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. conclusion: it is apparent that majority of the patients had p210 bcr-abl rearrangements. frequency of co-expression and rare fusion transcripts was very low.