Hemoglobin Structure and Thalassemias

Hemoglobin Structure

• Hemoglobin is a tetramer, consisting of four polypeptide chains.
• The tetramer is composed of two alpha chains and two beta chains.

Thalassemias

• Thalassemias are a group of disorders caused by abnormally low production of alpha or beta-globin chains.
• The disorders are named based on the specific globin chain that is decreased or absent.

Notation Conventions

• The '+' symbol indicates diminished, but not complete absence, of globin chain production (e.g. β+).
• The '0' symbol indicates complete absence of production of a globin chain by a gene (e.g. β0).

Thalassemia

• A silent carrier has one α-globin gene deleted, resulting in no anemia and asymptomatic patients.
• α-Thalassemia minor occurs when two α-globin genes are deleted, leading to mild anemia in patients.

α-Globin Gene Deletions

• Deletion of three α-globin genes results in Hgb H disease, characterized by severe anemia at birth and an elevated Hgb Bart's.
• Complete deletion of four α-globin genes leads to fetal hydrops.

This quiz covers the structure of hemoglobin, its composition, and thalassemias, a group of disorders caused by abnormal globin chain production. Learn about the alpha and beta chains, notation conventions, and more.