What are the two main types of thalassemia?

What are the two main types of thalassemia?

• A. Alpha-thalassemia
• B. Beta-thalassemia
• C. Both Alpha-thalassemia and Beta-thalassemia
• D. Sickle cell disease

Answer: (C)

Thalassemias are disorders caused by reduced production of one of the globin chains in hemoglobin. The two main forms are defined by which chain is affected: alpha-thalassemia and beta-thalassemia. Alpha-thalassemia arises from deletions of the alpha-globin genes on chromosome 16, with four gene copies in total. The clinical picture depends on how many genes are deleted, ranging from a mild or silent carrier state to HbH disease, and the most severe form causing hydrops fetalis in utero. Beta-thalassemia is caused by mutations in the beta-globin gene on chromosome 11, leading to reduced or absent beta-globin production. This results in a spectrum from mild anemia in beta-thalassemia trait to severe anemia requiring regular transfusions in beta-thalassemia major (Cooley’s anemia), often with iron overload. Sickle cell disease is a different hemoglobin disorder caused by a mutation in beta-globin that produces abnormal hemoglobin (HbS); it is not classified as a thalassemia, though a person could theoretically have overlapping conditions.

Thalassemias are disorders caused by reduced production of one of the globin chains in hemoglobin. The two main forms are defined by which chain is affected: alpha-thalassemia and beta-thalassemia.

Alpha-thalassemia arises from deletions of the alpha-globin genes on chromosome 16, with four gene copies in total. The clinical picture depends on how many genes are deleted, ranging from a mild or silent carrier state to HbH disease, and the most severe form causing hydrops fetalis in utero.

Beta-thalassemia is caused by mutations in the beta-globin gene on chromosome 11, leading to reduced or absent beta-globin production. This results in a spectrum from mild anemia in beta-thalassemia trait to severe anemia requiring regular transfusions in beta-thalassemia major (Cooley’s anemia), often with iron overload.

Sickle cell disease is a different hemoglobin disorder caused by a mutation in beta-globin that produces abnormal hemoglobin (HbS); it is not classified as a thalassemia, though a person could theoretically have overlapping conditions.