Frequency of BCR-ABL Transcript Types in Syrian CML Patients

Background. In Syria, CML patients are started on tyrosine kinase inhibitors (TKIs) and monitored until complete molecular response is achieved. BCR-ABL mRNA transcript type is not routinely identified, contrary to the recommendations. In this study we aimed to identify the frequency of different BCR-ABL transcripts in Syrian CML patients and highlight their significance on monitoring and treatment protocols. Methods. CML patients positive for BCR-ABL transcripts by quantitative RT-PCR were enrolled. BCR-ABL transcript types were investigated using a home-made PCR method that was adapted from published protocols and optimized. The transcript types were then confirmed using a commercially available research kit. Results. Twenty-four transcripts were found in 21 patients. The most common was b2a2, followed by b3a2, b3a3, and e1a3 present solely in 12 (57.1%), 3 (14.3%), 2 (9.5%), and 1 (4.8%), respectively. Three samples (14.3%) contained dual transcripts. While b3a2 transcript was apparently associated with warning molecular response to imatinib treatment, b2a2, b3a3, and e1a3 transcripts collectively proved otherwise (P = 0.047). Conclusion. It might be advisable to identify the BCR-ABL transcript type in CML patients at diagnosis, using an empirically verified method, in order to link the detected transcript with the clinical findings, possible resistance to treatment, and appropriate monitoring methods.