Hb A2 is increased in beta thalassemia because the relative lack of beta globin allows more delta chains to be incorporated into hemoglobin. Beta thalassemia is caused by mutations in the beta globin gene locus on chromosome 11.
What is alpha thalassemia hba1 HbA2?
Alpha-thalassemia is an autosomal recessive condition that affects the red blood cells. It can affect people of any ethnicity, but is more common in people who can trace their ancestry to Southeast Asia, India, equatorial Africa, the Mediterranean, or the Arabian Peninsula.
What is HbA2 thalassemia?
Hemoglobin A2 (HbA2) is a normal variant of hemoglobin A that consists of two alpha and two delta chains (α2δ2) and is found at low levels in normal human blood. Hemoglobin A2 may be increased in beta thalassemia or in people who are heterozygous for the beta thalassemia gene.
What is thalassemia alpha?
Alpha thalassemia is a blood disorder that reduces the production of hemoglobin . Hemoglobin is the protein in red blood cells that carries oxygen to cells throughout the body.
What does it mean if HbA2 is high?
Other causes of elevated HbA2 other than thalassemia include antiretroviral therapy, vitamin B12/folate deficiency, and hyperthyroidism. Hemoglobin electrophoresis and high-performance liquid chromatography can also elucidate other hemoglobinopathies complicating a beta-thalassemia trait.
Is thalassemia a Hemoglobinopathy?
Hemoglobinopathy and thalassemia are genetic disorders caused by aberrant hemoglobin; however, thalassemia is caused by reduced or absent synthesis of globin peptide chains1, while hemoglobinopathy is caused by alteration of the globin peptide chain conformation, which usually does not develop anemia33.
Is alpha thalassemia fatal?
Thalassemia major can be fatal. People with alpha thalassemia major die in infancy. People with beta thalassemia major require regular blood transfusions. There are other forms of thalassemia which are not as severe.
How much HbA2 is normal?
Normal Results HbA: 95% to 98% (0.95 to 0.98) HbA2: 2% to 3% (0.02 to 0.03)
What if HBA2 is low?
Low Hb A2 percentages were found in iron-deficiency anemia, hereditary persistance of fetal hemoglobin, and Hb H disease. In iron-deficiency anemia, the lowest levels of Hb A2 were observed in association with the most severe anemia.
What are the 4 types of alpha thalassemia?
There are 4 types of alpha thalassemia:
- Alpha thalassemia silent carrier. One gene is missing or damaged, and the other 3 are normal. Blood tests are usually normal.
- Alpha thalassemia carrier. Two genes are missing.
- Hemoglobin H disease. Three genes are missing.
- Alpha thalassemia major. All 4 genes are missing.
What is HbA2 levels?
HbA2, composing of two α chains and two δ chains, is a minor component of the hemoglobin present in normal adult red blood cells, accounting for about 2.5% of the total hemoglobin in healthy individuals. However, HbA2 level is also elevated in some pregnant women.
What causes alpha alpha thalassemia?
Alpha thalassemia typically results from deletions involving the HBA1 and HBA2 genes. Both of these genes provide instructions for making a protein called alpha-globin, which is a component (subunit) of hemoglobin. People have two copies of the HBA1 gene and two copies of the HBA2 gene in each cell. Each copy is called an allele.
Which HB types are most relevant to α-thalassemia?
The Hb types most relevant to α-thalassemia are: Hemoglobin A (HbA). Two α-globin chains and two β-globin chains (α 2 β 2) Hemoglobin F (HbF). Two α-globin chains and two γ-globin chains (α 2 γ 2)
What is the function of HBA1 and HBA2?
Both of these genes provide instructions for making a protein called alpha-globin, which is a component (subunit) of hemoglobin. Each person has two copies of the HBA1 gene and two copies of the HBA2 gene in each cell. Each copy is called an allele.
Does hemoglobin electrophoresis rule out beta thalassemia trait?
The hemoglobin electrophoresis with beta thalassemia trait usually has reduced or absent HbA, elevated levels of HbA2, and increased HbF. 2 However, a normal concentration of HbA2 does not rule out beta thalassemia trait, especially if there was coexistent iron deficiency, which can lower HbA2 levels into the normal range.
