Hemoglobin A2 (HBA2) Alpha-Globin Gene Deletion, 3.7-kb, Triple-Gene — Whole Blood, Qualitative
A blood-based genetic test that looks for a specific 3.7-kb deletion affecting the HBA2/HBA1 alpha-globin genes.
["Detecting this deletion may indicate alpha-thalassemia, but the number of affected gene copies and other genetic findings determine clinical significance."]
Key facts at a glance
- LOINC
- 85091-7
- Short code
- HBA2 alpha 3.7kb triple Bld Ql
- Synonyms
- HBA2 alpha 3.7kb triple Bld Ql
- Category
- liver
- Sample
- whole-blood
- Container
- Lavender-top (EDTA)
- Units
- N/A
- Ref low
- 44
- Ref high
- 147
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- Method
- molgen
- CPT
- 84075
- SNOMED
- 27550007
- Specimen volume
- 3 mL
- Stability
- Room temperature: 4h, Refrigerated: 24h
- Hemolysis max
- 0
- Lipemia max
- 0
- Icterus max
- 0
- TAT
- 4–24 hours
- Order
- routine
What is this test?
This is a qualitative genetic test performed on whole blood. It looks for a specific 3.7-kb deletion in the alpha-globin gene region, which includes the HBA2 and HBA1 genes. A triple-gene pattern means three alpha-globin gene copies are affected by the deletion.
Why might I need this test?
This test may be used to investigate alpha-thalassemia, particularly when blood counts suggest a hemoglobin disorder, when another test suggests reduced hemoglobin A2, or when a close relative has an alpha-globin deletion. It may also be included in genetic counseling or carrier evaluation.
How is the test performed?
A blood sample is collected, and the laboratory analyzes DNA for the targeted 3.7-kb deletion using a molecular testing method. The result is qualitative, meaning the report indicates whether the targeted deletion was detected; the exact laboratory method should appear on the test report.
How do I prepare for the test?
No fasting or medication changes are usually required for this blood test. Follow any specific instructions from the ordering clinician or laboratory, especially if testing is being coordinated with other family or genetic studies.
Reference range
Adult: 44-147 U/LN/A
No special preparation required. Avoid fatty meals before the test if possible.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
◆Associated findings1
Short name
Alpha-Globin 3.7-kb Deletion Test
Frequently asked questions
Is HBA2 the same thing as hemoglobin A2?
Does a positive result mean I have alpha-thalassemia?
Does this test detect every type of alpha-thalassemia?
Sources
- 1
- 2Lab Tests OnlineSource
- 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