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Test Code BA190 BCR/ABL1, p190, mRNA Detection, Reverse Transcription-PCR (RT-PCR), Quantitative, Monitoring Assay, Varies

Reporting Name

BCR/ABL1, p190, Quant, Monitor

Useful For

Monitoring response to therapy in patients with known e1/a2 BCR/ABL1 (p190) fusion forms

Performing Laboratory

Mayo Clinic Laboratories in Rochester

Specimen Type

Varies


Ordering 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

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

Test Classification

This test was developed and its performance characteristics determined by Mayo Clinic in a manner consistent with CLIA requirements. It has not been cleared or approved by the US Food and Drug Administration.

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.

Report Available

4 to 8 days

Reject Due To

Gross hemolysis Reject
Moderately to severely clotted Reject

Method Name

Quantitative Reverse Transcription-Polymerase Chain Reaction (RT-PCR)

Forms

1. Hematopathology Patient Information (T676)

2. If not ordering electronically, complete, print, and send a Hematopathology/Cytogenetics Test Request (T726) with the specimen.

Testing Algorithm

For information see BCR/ABL1 Ordering Guide for Blood and Bone Marrow.