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HelpTest Code BA190 BCR/ABL1, p190, mRNA Detection, Reverse Transcription-PCR (RT-PCR), Quantitative, Monitoring Assay, Varies
Reporting Name
BCR/ABL1, p190, Quant, MonitorUseful For
Monitoring response to therapy in patients with known e1/a2 BCR/ABL1 (p190) fusion forms
Testing Algorithm
For information see BCR/ABL1 Ordering Guide for Blood and Bone Marrow.
Method Name
Quantitative Reverse Transcription-Polymerase Chain Reaction (RT-PCR)
Performing Laboratory
Mayo Clinic Laboratories in Rochester
Specimen Type
VariesOrdering Guidance
This test should not be used to screen for BCR/ABL1 fusions at the time of diagnosis; order either BADX / BCR/ABL1, Qualitative, Diagnostic Assay, Varies; or BCRFX / BCR/ABL1 Qualitative Diagnostic Assay with Reflex to BCR/ABL1 p190 Quantitative Assay or BCR/ABL1 p210 Quantitative Assay, Varies should be ordered for that purpose.
To monitor patients carrying BCR/ABL1 fusion forms coding for the p210 protein, which includes most patients with chronic myeloid leukemia (CML); order BCRAB / BCR/ABL, p210, mRNA Detection, Reverse Transcription-PCR (RT-PCR), Quantitative, Monitoring Chronic Myeloid Leukemia (CML), Varies.
Shipping Instructions
Refrigerate specimens must arrive within 5 days (120 hours) of collection, and ambient specimens must arrive within 3 days (72 hours) of collection. Collect and package specimen as close to shipping time as possible.
Necessary Information
Pertinent clinical history including if the patient has a diagnosis of chronic myeloid leukemia or other BCR/ABL1-positive neoplasm information is required.
Specimen Required
Submit only 1 of the following specimens:
Preferred:
Specimen Type: Whole blood
Container/Tube:
Preferred: Lavender top (EDTA)
Acceptable: Yellow top (ACD)
Specimen Volume: 10 mL
Collection Instructions:
1. Invert several times to mix blood.
2. Send whole blood specimen in original tube. Do not aliquot.
3. Label specimen as blood.
Specimen Type: Bone marrow
Container/Tube:
Preferred: Lavender top (EDTA)
Acceptable: Yellow top (ACD)
Specimen Volume: 4 mL
Collection Instructions:
1. Invert several times to mix bone marrow.
2. Send bone marrow specimen in original tube. Do not aliquot.
3. Label specimen as bone marrow.
Specimen Minimum Volume
Blood: 8 mL
Bone marrow: 2 mL
Specimen Stability Information
| Specimen Type | Temperature | Time | Special Container |
|---|---|---|---|
| Varies | Refrigerated (preferred) | 5 days | PURPLE OR PINK TOP/EDTA |
| Ambient | 72 hours | PURPLE OR PINK TOP/EDTA |
Reject Due To
| Gross hemolysis | Reject |
| Moderately to severely clotted | Reject |
Special Instructions
Reference Values
The presence or absence of the BCR/ABL1 messenger RNA fusion form producing the p190 fusion protein is reported. If positive, the level is reported as the ratio of BCR/ABL1 (p190) transcript to ABL1 transcript in the form of a percentage.
Day(s) Performed
Monday through Friday
CPT Code Information
81207
LOINC Code Information
| Test ID | Test Order Name | Order LOINC Value |
|---|---|---|
| BA190 | BCR/ABL1, p190, Quant, Monitor | 21823-0 |
| Result ID | Test Result Name | Result LOINC Value |
|---|---|---|
| 39470 | BCR/ABL1 p190 Result | No LOINC Needed |
| MP002 | Specimen Type | 31208-2 |
| 19765 | Interpretation | 69047-9 |
Clinical Information
Messenger RNA (mRNA) transcribed from BCR/ABL1 (fusion of the breakpoint cluster region gene [BCR] at chromosome 22q11 to the Abelson gene [ABL1] at chromosome 9q34) is detected in all patients with chronic myeloid leukemia (CML) and a subset of patients with both acute lymphoblastic leukemia (ALL) and acute myeloid leukemia (AML). Although breakpoints in the BCR and ABL1 genes may occur in a variety of locations, splicing of the primary RNA transcripts result in only 8 fusion site variants (e1/a2, e6/a2, e13/a2, e14/a2, e19/a2, and e1/a3, e13/a3, e14/a3), which incorporate the entire sequence of the exons on both sides of the fusion site. The e1/a2 and e1/a3 fusion forms produce a 190-kDa protein designated p190. This BCR/ABL1 protein form is found in approximately 75% of patients with childhood ALL and approximately 50% of patients with adult ALL, with the majority arising from e1/a2 mRNA. The p190 is also the predominant fusion form in a small subset of patients with CML, although the vast majority of CML cases contain the p210 protein, typically from e13/a2 or e14/a2 mRNA fusions. Other fusion forms are very rare.
Quantitative reverse-transcription polymerase chain reaction (qRT-PCR) is the most sensitive method for monitoring BCR/ABL1 levels during treatment. This test detects mRNA coding for the most common p190 fusion form (e1/a2).
Interpretation
An interpretive report will be provided.
Cautions
This test detects only the e1/a2 BCR/ABL1 (p190) fusion form. Other fusion forms are not detected by this assay, including those containing the BCR e13 and e14 exons, which code for the p210 protein commonly found in chronic myeloid leukemia (CML), and the rare e1/a3 (p190) fusion form.
The precision of this assay at very low BCR/ABL1 levels is less reliable, such that inter-run variation can be more variable. If the results are being used to make major therapeutic decisions, significant changes during monitoring should be verified with a subsequent specimen.
Results of this assay cannot be directly compared with results generated from other polymerase chain reaction (PCR) assays, including identical assays performed in other laboratories. Monitoring should be performed using the same method and laboratory for each subsequent specimen.
The results of this assay cannot be directly compared with BCR/ABL1 results obtained using fluorescence in situ hybridization (FISH) technology. FISH measures DNA alleles and this PCR-based assay measures messenger RNA (mRNA) transcripts. Because a single DNA allele can produce many mRNA transcripts, the values are not directly comparable.
Blood is the specimen of choice for monitoring. While most patients show similar BCR/ABL1 levels in blood and bone marrow drawn at the same time, some patients have a consistent difference in the levels in blood and bone marrow such that altering specimen types during monitoring can lead to confusion.
Assay precision does not appear to be significantly affected by specimen transport or moderate delays in processing. However, in specimen with very low levels of BCR/ABL1, these conditions may cause sufficient RNA degradation to produce false-negative results. Thus, specimens should be shipped as quickly as possible. Ambient specimens over 3 days old and refrigerate specimens over 5 days old at the time of receipt are unacceptable.
Method Description
Total RNA is extracted and reverse transcribed to complementary DNA. Quantitative real time polymerase chain reaction is performed and p190/ABL quantitative levels are determined using TaqMan-type probe technology. The data is analyzed for relative quantification with calibrator normalization and efficiency correction. The reference gene, ABL1, is used to control for RNA degradation in the sample and the calibrator is used to control for inter-run variations. A normalized ratio of BCR/ABL1 (p190) mRNA:ABL1 mRNA is obtained and reported in the form of a percentage.(Unpublished Mayo method)