Haemoglobin is the substance in the blood that carries oxygen around the body. The type of Adult haemoglobin in person is determined by the inherited genes from parents. Genes always come in pairs one from the father and one from the mother. Hence, every individual inherits two Adult Haemoglobin genes. The normal and most common Adult haemoglobin gene combination that an individual can inherit from their parents is Haemoglobin AA and is written as Hb AA.
Hemoglobin A2 (HbA2) is a normal variant of hemoglobin A .It has two alpha and two delta chains (α2δ2) and is found at low levels in normal human blood.The biological role of this protein is not yet known.
During the early embryonic period itself this is produced in the fetus, irrespective of the type of major Adult haemoglobin they have inherited from their parents.
Clinical significance of Hemoglobin A2
Haemoglobin A2 is a redundant haemoglobin because this is not an efficient at carrier of oxygen in the body, however, But it has certain clinical significance because it is useful for helping the laboratory to diagnose some genetic mutations of haemoglobin, based on the type of genetic mutation and underlying disease the level of A2 will rise or fall.
Causes of Increased HbA2 levels
- Beta thalassemia
- Sickle cell anemia
- Megaloblastic anemia
- Hyperthyroidism
- Unstable Hemoglobinopathies
- Malaria (doubtfull cases)
- Iron deficiency Anemia
- Alpha thalassemia
- Delta thalassemia
- Sideroblastic anemia
- Myelodysplastic syndromes
- Acute myelocytic leukemia (minor reduction)
- Hb Lepore
