Test Overview
Reverse transcription followed by Real-Time Polymerase Chain Reaction (PCR).
The t(9;22) chromosomal translocation is a hallmark of chronic myelogenous leukemia (CML) and occurs in a proportion of acute lymphocytic leukemias (ALL). At the molecular level, it creates a chimeric gene on the derivative chromosome 22 that is comprised of the promoter and 5’ region of the BCR gene (22q11) fused to the 3’ region of the ABL1 gene (9q34). Transcription of this fusion gene, which is under the control of the ubiquitously active BCR promoter, results in a BCR/ABL1 chimeric oncoprotein that is critical for malignant transformation. Depending upon the location of the BCR and ABL1 gene breakpoints, the resulting chimeric fusion transcript can assume one of several forms, including the b2a2 and b3a2 forms, which both encode a p210 protein (>95% of CML cases, approximately 50% of adult ALL cases, approximately 10% of pediatric ALL cases), the e1a2 form, which encodes the p190 protein (2-3% of CML cases, 50% of ALL cases, approximately 90% of pediatric ALL cases), or an e19a2 form which encodes the p230 protein form (very rare). This test can detect and quantify both the p210 (b2a2, b3a2) and p190 (e1a2) transcripts by reverse transcription real-time PCR (RT-qPCR) for diagnosis and monitoring of CML and ALL. The type of transcript will be reported (p210 or p190). Results for the p210 transcript are reported on the International Scale (IS) and with Molecular Reduction (MR) value. Result for the p190 transcript are reported as a ratio of %BCR/ABL1:ABL1. The limit of quantification for p210 is 0.002%IS (MR4.7) and p190 is 0.0025%. Please note that both tests (p210 and p190) will be performed until a transcript is detected. Subsequent testing on the same patient will be limited to the transcript previously identified.
Interpretive report provided.
* Reference ranges may change over time. Please refer to the original patient report when evaluating results.
Only BCR/ABL1:ABL1 changes of 0.5 log or greater should be considered significant. The reportable range of quantification for p210 is 50%IS (MR0.3) to 0.002%IS (MR4.7) and for p190 is 25 to 0.0025% BCR/ABL1:ABL1. Accurate quantitation of results cannot be performed above and below these ranges and will be reported as Positive, above the limit of quantitation or Positive, below the limit of quantitation, respectively. Some patients with very low levels of BCR/ABL1 transcript (<0.002%IS (>MR4.7) for p210 and <0.0025% BCR/ABL1:ABL1 for p190) may be reported as Undetected. Hence, an Undetected result does not preclude the presence of low levels of leukemic cells in the patient. This assay will not detect rare fusion transcripts such as the p230 transcript. Specimens older than 48-72 hours may result in failed testing due to RNA degradation.
Test Details
2 - 7 days
- BCRABL Quantitation by PCR
- Break Point Cluster Region (bcr) Assay
- Breakpoint Cluster Region (bcr) Analysis
- t(9;22) Translocation
Specimen Requirements
Collect blood or bone marrow in a lavender top tube. Refrigerate and send intact blood or bone marrow specimen within 48 hours of collection. Fresh tissue (preferably 0.5cm3, sent in RPMI) and fresh aspirates or body fluids are acceptable. Refrigerate and send, preferably within 24 hours. Frozen tissue specimens – preferably frozen with 1 hour of collection – may also be sent frozen on dry ice. Fresh cell suspensions in RPMI should be refrigerated and sent, preferably within 48 hours. Frozen cell suspensions – preferably frozen with 1 hour of collection – may also be sent frozen on dry ice.
Extracted RNA is also acceptable if extracted in a CLIA certified laboratory.
Additional Information
By ordering this test the clinician acknowledges that informed consent has been obtained from the patient as required by applicable state or federal laws and the ordering clinician has authorization from the patient permitting MLabs to report the test results to the ordering clinician. Test includes pathologist interpretation of results billed as a separate additional charge. This test is not available without interpretation.