Which globin chains are affected in beta thalassemia?

Beta-thalassemia is caused by the reduced (beta+) or absent (beta0) synthesis of the beta globin chains of the hemoglobin (Hb) tetramer, which is made up of two alpha globin and two beta globin chains (alpha2beta2).

Which chain of hemoglobin is affected in thalassemia?

Thalassemias are a heterogeneous grouping of genetic disorders that result from a decreased synthesis of alpha or beta chains of hemoglobin (Hb). Hemoglobin serves as the oxygen-carrying component of the red blood cells.

Which chain is affected in thalassemia?

The hemoglobin beta gene (HBB) encodes the β-chain and is located on chromosome 11. In α-thalassemia, there is deficient synthesis of α-chains. The resulting excess of β-chains bind oxygen poorly, leading to a low concentration of oxygen in tissues (hypoxemia). Similarly, in β-thalassemia there is a lack of β-chains.

What type of mutation occurs in beta thalassemia?

Beta thalassemia is caused by mutations in the hemoglobin beta (HBB) gene. Individuals with beta thalassemia minor have a mutation in one HBB gene, while individuals with the intermediate and major forms have mutations in both HBB genes.

Why is HbA2 increased in beta thalassemia?

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.

Does low MCV mean thalassemia?

These include the mean corpuscular volume (MCV), a measurement of the size of the red blood cells. A low MCV is often the first indication of thalassemia. If the MCV is low and iron deficiency has been ruled out as a cause, thalassemia should be considered.

Why is HBA2 increased in beta thalassemia?

What is beta globin chain?

Beta-globin is a component (subunit) of a larger protein called hemoglobin, which is located inside red blood cells. In adults, hemoglobin normally consists of four protein subunits: two subunits of beta-globin and two subunits of a protein called alpha-globin, which is produced from another gene called HBA.

What are beta chains?

β subunits regulate expression and membrane trafficking of α subunits, and modify the peak Na+ currents and the kinetics and voltage dependence particularly of their inactivation properties (Isom et al., 1995; From: Encyclopedia of Bone Biology, 2020.

What is the function of beta globin?

The beta globin protein is one of the subunits of hemoglobin, a protein necessary for the oxygen-carrying function of red blood cells. People with the sickle cell mutation in both copies of the HBB gene produce proteins that clump together and lead to changes in the shape and behavior of red blood cells.

What is HbA2 thalassemia?

The increase in hemoglobin A2 (HbA2) level is the most significant parameter in the identification of β-thalassemia carriers.

When is HbA2 elevated?

Hemoglobin A2 may be increased in beta thalassemia or in people who are heterozygous for the beta thalassemia gene. HbA2 exists in small amounts in all adult humans (1.5-3.1% of all hemoglobin molecules) and is approximately normal in people with sickle-cell disease. Its biological importance is not yet known.