What is Hemoglobin?
Hemoglobin is a
protein found in red blood cells that is responsible for transporting oxygen from the lungs to the tissues and returning carbon dioxide from the tissues to the lungs. It is composed of four polypeptide chains, each with an iron-containing heme group that binds oxygen.
What are Structural Hemoglobin Variants?
Structural hemoglobin variants are alterations in the amino acid sequence of the globin chains. These alterations can affect the properties and function of hemoglobin, leading to various clinical conditions. These variants are typically the result of
mutations in the genes that encode the globin proteins.
Hemoglobin S (HbS): The most well-known variant, associated with sickle cell disease, caused by a mutation in the β-globin chain.
Hemoglobin C (HbC): Another β-globin variant, often leading to a mild hemolytic anemia.
Hemoglobin E (HbE): A variant common in Southeast Asia, associated with a mild form of β-thalassemia.
Hemoglobin D (HbD): Variants such as HbD-Punjab can lead to mild hemolytic anemia.
Sickle Cell Anemia: In HbS, red blood cells become sickle-shaped, leading to vaso-occlusive crises and tissue ischemia.
Hemoglobin C Disease: HbC can cause red blood cells to form
target cells, which are cells with a bullseye appearance.
Thalassemias: Variants like HbE can result in hypochromic, microcytic anemia with increased red blood cell turnover.
Blood Smears: Microscopic examination of blood smears can reveal characteristic cell shapes, such as sickle cells or target cells.
Electrophoresis: Hemoglobin electrophoresis separates different forms of hemoglobin based on their charge and structure.
Molecular Techniques: DNA analysis can identify specific mutations responsible for hemoglobin variants.
Sickle Cell Disease: Chronic pain, anemia, and increased risk of infections and organ damage.
Hemoglobin C Disease: Mild to moderate hemolytic anemia and splenomegaly.
Hemoglobin E Disease: Generally mild symptoms, but can complicate other hemoglobinopathies.
