What is HbA in 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.

Why does HbA2 increase 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.

How does beta thalassemia cause anemia?

A lack of beta-globin leads to a reduced amount of functional hemoglobin. Without sufficient hemoglobin, red blood cells do not develop normally, causing a shortage of mature red blood cells. The low number of mature red blood cells leads to anemia and other associated health problems in people with beta thalassemia.

What is the RBC morphologic features in β thalassemia?

The diagnosis of β-thalassemia relies on measuring red blood cell indices that reveal microcytic hypochromic anemia, nucleated red blood cells on peripheral blood smear, hemoglobin analysis that reveals decreased amounts of HbA and increased amounts of hemoglobin F (HbF) after age 12 months, and the clinical severity …

What is normal range of HbA?

Normal Results HbA: 95% to 98% (0.95 to 0.98) HbA2: 2% to 3% (0.02 to 0.03) HbE: Absent. HbF: 0.8% to 2% (0.008 to 0.02)

What is HbA and HbA2?

Adult hemoglobin A (HbA) has two alpha and two beta chains (alpha2 beta2), whereas hemoglobin A2 (HbA2) has two alpha and two delta chains (alpha2 delta2). At birth, HbF accounts for approximately 80 percent of hemoglobin and HbA accounts for 20 percent.

What does low HbA2 mean?

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.

Why is RBC count high in thalassemia?

In the case of β-thalassemia, which is due to defective production of the β-globin chain of hemoglobin, the free α-globin chains precipitate in erythroid precursors causing anemia primarily due to impaired production of red blood cells.

What is the difference between alpha and beta-thalassemia?

When thalassemia is called “alpha” or “beta,” this refers to the part of hemoglobin that isn’t being made. If either the alpha or beta part is not made, there aren’t enough building blocks to make normal amounts of hemoglobin. Low alpha is called alpha thalassemia. Low beta is called beta thalassemia.

What is HBA1 and HBA2?

The HBA2 gene provides instructions for making a protein called alpha-globin. This protein is also produced from a nearly identical gene called HBA1. These two alpha-globin genes are located close together in a region of chromosome 16 known as the alpha-globin locus.

What is the RBC count in thalassemia?

Some practitioners use the Mentzer index (Mentzer index = MCV/red blood cell count [RCV]) to discriminate between thalassemia trait and iron deficiency. In general, those with a Mentzer index of less than 13 have thalassemia trait, while those with iron deficiency usually have an index of greater than 13.

What is HbA in blood test?

A hemoglobin A1c (HbA1c) test measures the amount of blood sugar (glucose) attached to hemoglobin. Hemoglobin is the part of your red blood cells that carries oxygen from your lungs to the rest of your body.

What causes alpha thalassemia ( HBH ) with no anemia?

The two-gene deletion causes alpha thalassemia trait (minor) with microcytosis and usually no anemia. The three-gene deletion results in significant production of hemoglobin H (HbH), which has four beta chains (beta 4). Alpha thalassemia intermedia, or HbH disease, causes microcytic anemia, hemolysis, and splenomegaly.

What are the clinical characteristics of beta thalassemia?

Excerpt Clinical characteristics: Beta-thalassemia (β-thalassemia) is characterized by reduced synthesis of the hemoglobin subunit beta (hemoglobin beta chain) that results in microcytic hypochromic anemia, an abnormal peripheral blood smear with nucleated red blood cells, and reduced amounts of hemoglobin A (HbA) on hemoglobin analysis.

What is the difference between HBA and HBA 2?

HbA contains two α globin chains and two β globin chains , and HbA 2 contains two α globin chains and two δ globin chains. They are arranged into a heterotetramer. Thalassemia patients produce a deficiency of either α or β globin, unlike sickle cell disease, which produces a specific mutant form of β globin.

Can a person with beta thalassemia take iron supplements?

Persons with anemia from thalassemia trait should not take iron supplements unless they have coexistent iron deficiency. Persons with beta thalassemia major require periodic lifelong blood transfusions to maintain hemoglobin levels higher than 9.5 g per dL (95 g per L) and sustain normal growth.