Analysis of BCR-ABL Fusion Transcripts of Chronic Myeloid Leukemia Patients in Korea

Kim, Yoo Li; Hwang, Ji Yeon; Kim, Chun Choo; Kim, Dong Wook

Abstract

BACKGROUND: The BCR-ABL rearrangement, the molecular hallmark of chronic myeloid leukemia (CML) can be used as a marker to identify residual disease after therapy. So far, very limited data exists in Korea regarding the frequency of BCR-ABL fusion gene in patients with CML. The objective of this study was to identify the type of BCR-ABL fusion variants of CML patients in Korea.
METHODS
We performed a two-step reverse transcription-polymerase chain reaction(RT- PCR) to detect BCR-ABL specific mRNA in 154 CML patients who were diagnosed by histologic examination and cytogenetics at our institute between January 1997 and November 2000. We used different primer set to amplify various breakpoints of BCR-ABL fusion gene.
RESULTS
All patients showed at least one of BCR-ABL transcripts. One hundred and four of 154 patients (67.5%) represented b3a2 transcript that was most frequent transcript in our CML patients. 44 patients (28.6%) had b2a2 transcript and b3a2+b2a2 splicing variants were identified in 5 cases (3.25%). In addition, c3a2 variant which is very rare transcript was identified in a patient (0.65%).
CONCLUSIONS
The RT-PCR assay could identify the presence of the BCR-ABL transcript in all patients with exquisite sensitivity. The frequency of BCR-ABL transcript was different from that of western countries but similar to that of eastern. Long-term follow up of CML patients with different variants are needed to determine the prognostic importance of each gene variant.