Detection of BCR ABL Major Fusion Transcripts

The t(9;22)(q34;q11.2) translocation resulting in BCR::ABL1 fusion transcripts is seen in nearly all cases of chronic myelogenous leukemia (CML) and in a subset of acute lymphoblastic leukemia/lymphoma (ALL). This assay detects and quantifies e13a2 and e14a2 BCR::ABL1 transcripts (p210) arising from BCR breakpoints in the major breakpoint cluster region. The assay can be used for diagnosis, classification, post-treatment monitoring and minimal residual disease detection. The results are reported as the percentage international scale (%IS) for interlaboratory comparison of molecular milestones such as major molecular response (MMR). The test results must be interpreted in conjunction with clinical findings, hematologic data and other laboratory studies.

Total RNA is extracted from the provided sample and reverse-transcribed into complementary DNA (cDNA). Quantitative real-time multiplex PCR amplification is performed using primers designed to t(9;22)(q34;q11.2)/BCR::ABL1 fusion transcripts in leukemia. Specifically, the assay is designed to detect e13a2 (b2a2) and e14a2(b3a2) involving the major breakpoint region. Standard curves for BCR::ABL1 and the ABL1 control are included in each assay to quantify the transcripts. A normalized copy number (NCN) is calculated for each sample as #BCR::ABL1 cDNA molecules/#ABL1 cDNA molecules. The NCN is then converted to a value on the international scale (IS) using a validated reference sample calibrated to a standard set of diagnostic specimens. The results are reported as percentage international scale (%IS).

1. Limit of detection: MR of 4.7 or %IS of 0.002%
2. Limit of quantification (LOQ): MR of 4.7 or %IS of 0.002%
3. Analytical measurement range: %IS of 0.002%–50%

Five to 10 working days 

10–30 ml peripheral blood in lavender top (EDTA) tube, senton wet ice

or

2–5 ml of bone marrow aspirate in lavender top (EDTA) tube, sent on wet ice

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