HBA2: Hemoglobin Subunit Alpha 2
Essential component of hemoglobin, critical for oxygen transport; mutations cause alpha-thalassemia
Gene Information Card
| Symbol | HBA2 |
|---|---|
| Full Name | Hemoglobin Subunit Alpha 2 |
| Gene Type | Protein coding |
| Chromosomal Location | 16p13.3 |
| NCBI Gene ID | 3040 ncbi.nlm.nih.gov/gene/3040 |
| Ensembl ID | ENSG00000188536 |
| UniProt ID | P69905 |
| OMIM ID | 141850 |
| HGNC ID | 4824 |
| Aliases | HBH, HBA-T2, alpha2-globin |
Description
HBA2 encodes the alpha-2 globin chain, one of two alpha-globin chains (HBA1 and HBA2) that, together with beta-globin chains, form adult hemoglobin (HbA, α2β2). The gene is located on chromosome 16 in a cluster with HBA1 and other alpha-like globin genes. HBA2 is expressed predominantly in erythroid cells and is essential for oxygen transport. Mutations or deletions in HBA2 can lead to alpha-thalassemia, a common inherited blood disorder characterized by reduced or absent alpha-globin synthesis.
Disease Associations
| Disease category | Pathophysiological mechanism | Genomic evidence |
|---|---|---|
| Alpha-thalassemia | Deletions or point mutations in HBA2 reduce alpha-globin production, causing imbalance of globin chains and ineffective erythropoiesis. | ClinVar, OMIM |
| Hemoglobin H disease | Compound heterozygosity for alpha0-thalassemia (deletion of both HBA1 and HBA2) and alpha+-thalassemia leads to excess beta-globin tetramers (HbH). | ClinVar, OMIM |
| Hb Bart's hydrops fetalis | Homozygous deletion of all four alpha-globin genes (including HBA2) results in no alpha-globin, incompatible with life. | OMIM |
| Hemoglobin variants (e.g., Hb Constant Spring) | Nonsense or frameshift mutations in HBA2 produce elongated alpha-globin chains, leading to unstable hemoglobin and mild thalassemia. | ClinVar, OMIM |
Expression Profile
Tissue Expression
| Tissue | nTPM | level |
|---|---|---|
| Bone Marrow | 125.6 | High |
| Spleen | 45.3 | Medium |
| Blood (whole) | 38.7 | Medium |
| Liver (fetal) | 22.1 | Medium |
| Lung | 1.2 | Low |
Cell Line Expression
| Cell Line | nTPM | Notes |
|---|---|---|
| K562 (erythroleukemia) | 156.8 | High expression; used for globin gene regulation studies |
| HEL (erythroleukemia) | 98.4 | High expression |
| HepG2 (hepatocellular) | 0.5 | Very low; not erythroid |
| HeLa (cervical) | 0.2 | Very low |
Data source：Human Protein Atlas（proteinatlas.org）
Mutations & Variants
Hotspot Mutations
| Variant | Type | Frequency | Functional Description |
|---|---|---|---|
| c.427T>C (p.Ter143Gln) | Nonsense-to-readthrough | Rare | Hb Constant Spring; elongated alpha-globin, mild alpha-thalassemia |
| c.95+1G>A | Splice donor | Rare | Alpha-thalassemia; aberrant splicing, reduced alpha-globin |
| c.369C>G (p.Tyr123Ter) | Nonsense | Rare | Alpha-thalassemia; premature termination |
| --SEA (Southeast Asian deletion) | Large deletion | Common in SEA | Alpha0-thalassemia; removes HBA1 and HBA2 |
Mutation functional classification
Loss of Function (LOF)
Most HBA2 mutations (deletions, nonsense, frameshift) cause loss of alpha-globin function, leading to alpha-thalassemia.
Gain of Function (GOF)
Not described; no known gain-of-function mutations in HBA2.
Dominant Negative (DN)
Some missense variants (e.g., Hb Q-India) may produce unstable alpha-globin that exerts a dominant-negative effect on hemoglobin assembly.
View complete mutation data：
Gene Ontology (GO)
Pathways
• Erythropoiesis (WP:WP179)
• Oxygen transport (Reactome:R-HSA-1480926)
• Heme biosynthesis (Reactome:R-HSA-189451)
Protein Summary
The alpha-2 globin protein (141 amino acids) is a monomer that binds heme and participates in oxygen transport as part of the hemoglobin tetramer. It is encoded by HBA2, which is nearly identical to HBA1 in coding sequence but differs in regulatory regions. The protein is highly conserved and expressed in erythroid cells. Mutations can cause alpha-thalassemia or hemoglobin variants.
Related Services
Related Products
| Product name | Cat.No. | Species | Gene ID | |
|---|---|---|---|---|
| HBA2 Knockout HEK293 Cell Line | EDJ-KQ50341 | Human | 3040 | Details Get a Quote |
| HBA2 Knockout HeLa Cell Line | EDJ-KQ53493 | Human | 3040 | Details Get a Quote |
| HBA2 Knockout A-549 Cell Line | EDJ-KQ61964 | Human | 3040 | Details Get a Quote |
| HBA2 Knockout HCT 116 Cell Line | EDJ-KQ70445 | Human | 3040 | Details Get a Quote |
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