Abstract
Background and Aims : A diagnostic feature of chronic myelogenous leukemia (CML) is the presence of BCR/ABL fusion genes. There are two types BCR/ABL transcripts : CML-and acute lymphoblastic leukemia (ALL) -types. ALL-type BCR/ABL transcript is detectable in approximately 50% of CML patients, and its abundance is generally less than that of CML-type BCR/ABL. However, the exact stoichiometry has not been established. In this report, we sought to quantify these two types of BCR/ ABL transcripts in patients with CML in chronic phase (CP) by highly sensitive quantitative PCR methods. Methods : We examined two types of the BCR/ABL transcripts in seven patients with CML in chronic phase using reverse transcription and real-time quantitative polymerase chain reaction (RQ-PCR). The BCR/ABL expression was normalized to the expression of GAPDH. Results : In 5 out of 7 patients, ALL-type BCR/ABL could be detected. The ratio of CML-type BCR/ABL to GAPDH ranged from 4.94 × 10-3 to 81.8 × 10-3, and that of ALL-type to GAPDH ranged from 0.15 × 10-3 to 0.85 × 10-3. Thus, ALL-type transcript levels ranged from 1.3 to 54.3% of the CML-type levels. Conclusions : In CML patients, expression of ALL-type BCR/ABL was 1 to 2 orders of magnitude lower than expression of CML-type BCR/ABL..
