Abstract

 Background and Objectives

 A specific chromosomal abnormality, the Philadelphia chromosome (Ph), is present in more than 90% of CML patients. The aberration results from a reciprocal translocation between chromosome 9 and 22, creating a BCR-ABL fusion gene. Major forms of BCR-ABL fusion are b3a2, b2a2, and e1a2. Less common fusion genes are b3a3 or b2a3 (p203) and el9a2 (p230). The aim of this study was to set up a multiplex RT-PCR assay and determine the frequency of different fusion genes in 75 Iranian patients with CML.

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 Materials and Methods

 In this experimental study, peripheral blood samples from 75 adult Iranian CML patients were analyzed by multiplex RT-PCR to detect different types of BCR-ABL transcripts of the t(9:22).

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 Results

 All of the examined cases were positive for some type of BCR/ABL rearrangement. The majority of patients (82.6%) expressed one of the P210 BCR-ABL transcripts (b3a2, 62% and b2a2, 20%), while the remaining showed either one of the transcripts of b3a3, b2a3, ela2 or coexpression of b3a2 and b2a2. The rate of coexpression of the b3a2 and b2a2 was 5%.

 Conclusions

 It is possible to detect rare fusions other than common ones through multiplex method. In Iranian CML patients, b3a2 was three times more frequent than b2a2 shown to be higher as compared with other studies. Probably, the kind of fusion is of clinical importance and helps us in understanding t(9:22) leukemic cells pathogenesis.

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 Key words : Chronic myeloid leukemia, RT-PCR, Philadelphia chromosome