Lesson 3 of 4
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Thalassemia

September 5, 2022

Genetic diseases of defective globin chain of hemoglobin with impairment of production. Result lead to abnormal globin precipitation destruct the erythrocyte membrane, hemolysis occur. Microcytic anemia.

Thalassemia is a genetic disease that is passed down to a person from his parents. There are two main types of it namely alpha thalassemia and beta thalassemia. It is more common among people of Italian, Greek, Turkish, Middle Eastern, South Asian, and African descent.

Normal hemoglobin is composed of two pairs of globin chains, alpha (α) and beta (β). Each globin chain is attached to an iron-containing heme moiety. This is called HbA. The β-globin chains are encoded by a gene on chromosome 11. The α-globin chains are encoded by two closely linked genes on chromosome 16.

HbA, HbA2, HbF are found in adults. HbF is found in infants and children.
Type Globin ChainsPercentage
HbATwo alpha (α) + two beta (β)95%-98%
HbA2Two alpha (α) + two delta (δ)2%-3%
HbFTwo Alpha (α) + Two Gamma (γ)0.8%-2%

Cause of the disease

Thalassemia patients have low or complete absence of α or β globins. Hemoglobin molecules are composed of alpha and beta chains that are susceptible to mutations. In thalassemia, the production of alpha or beta chains decreases, resulting in alpha-thalassemia or beta-thalassemia.

Alpha-thalassemia