Bcrabl1b3a2bldtql
This test detects the BCR-ABL1 b3a2 fusion protein in blood or tissue to help diagnose and monitor certain types of leukemia.
{"Detects a specific genetic abnormality (b3a2 fusion) associated with chronic myeloid leukemia (CML)","Used to confirm diagnosis, predict prognosis, and monitor treatment response","Performed on a blood sample using molecular genetics techniques like PCR","Results help doctors determine if targeted therapies like imatinib are working","Regular testing tracks whether the cancer is in remission or recurring"}
Key facts at a glance
- LOINC
- 49491-4
- Short code
- BCRABLb3a2
- Synonyms
- BCR-ABL1 b3a2 Bld/T Ql
- Category
- chemistry
- Sample
- whole-blood
- Container
- Lavender-top (EDTA) or pink-top (K2-EDTA) blood collection tube; sterile container for tissue specimens
- Units
- N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 0–120 years
- Method
- molgen
- CPT
- 81206
- SNOMED
- 385526006
- Specimen volume
- Whole blood: 3-5 mL (minimum 1 mL); Bone marrow: 1-3 mL; Tissue: adequate amount per institutional protocol
- Stability
- Whole blood: Room temperature 24 hours; Refrigerated (2-8°C) up to 5 days; Frozen (-20°C or lower) up to 1 month for extracted RNA. RNA should be extracted promptly for optimal results. Bone marrow specimens should be processed within 24 hours.
- Hemolysis max
- 0
- Lipemia max
- 0
- Icterus max
- 0
- TAT
- 24–168 hours
- Order
- routine
What is this test?
The BCR-ABL1 b3a2 fusion protein test is a specialized molecular genetics test that looks for a specific abnormal fusion gene in your blood or tissue. This fusion gene (called b3a2) forms when parts of two different chromosomes swap places, creating what scientists call the Philadelphia chromosome. This genetic abnormality is most commonly found in chronic myeloid leukemia (CML) and some cases of acute lymphoblastic leukemia (ALL).
How is the test performed?
A healthcare professional will collect a blood sample from a vein in your arm. In some cases, a tissue sample (such as bone marrow) may also be used. The sample is then sent to a laboratory where technicians use molecular genetics methods—most commonly polymerase chain reaction (PCR)—to detect the presence of the b3a2 fusion protein. This test is highly sensitive and can detect even tiny amounts of the abnormal gene.
Why is this test important?
Finding the b3a2 fusion gene helps your doctor confirm a diagnosis of CML or Philadelphia-positive ALL. The test also provides important information about your prognosis (outlook) and helps monitor how well treatment is working. If you're receiving targeted drug therapy (like tyrosine kinase inhibitors such as imatinib), regular testing shows whether the number of fusion genes is decreasing—indicating the treatment is effective—or increasing—suggesting the disease may be progressing or becoming resistant to treatment.
Reference range
Negative (BCR-ABL1 b3a2 fusion transcript not detected). A positive result indicates the presence of the BCR-ABL1 b3a2 fusion transcript, which is associated with Chronic Myeloid Leukemia (CML) or Philadelphia chromosome-positive Acute Lymphoblastic Leukemia (Ph+ ALL). Results should be interpreted in conjunction with cytogenetic analysis and clinical findings.N/A
No special patient preparation is required. Patient should be informed about the purpose of the test, which detects a specific genetic rearrangement associated with leukemia. Informed consent may be required per institutional policy for genetic testing.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
◆Associated findings1
Frequently asked questions
Do I need to fast before this test?
How often will I need this test?
What does it mean if my test results change over time?
Is this test only for people already diagnosed with leukemia?
Are there any risks from this test?
Sources
- 1
- 2
- 3
Click any link to access the full source. PubMed Central (PMC) links provide free full-text access.
This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.
This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.
If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.
Medically reviewed by WellAlly Editorial Team Last reviewed August 16, 2026. · Read our editorial policy