1. Hemoglobin Types and Variants
Posted by ThirdAge Editorial Staff on April 30, 2010 5:23 PM
Hemoglobin variants are abnormal forms of hemoglobin, an iron-containing protein molecule
found in all red blood cells. Hemoglobin binds oxygen in the lungs, carries oxygen from the lungs
throughout the body, and releases oxygen to the body's cells and tissues. Hemoglobin variants
occur when there are genetic changes in the globin genes, affecting the structure, the behavior,
the stability and/or the production rate of the hemoglobin.
Normal Hemoglobin Types
Normal hemoglobin types found in our body include Hb A, Hb A2 and Hb F. Hb A composes
about 95 to 98 percent of Hb found in your body and contains two alpha protein chains and two
beta protein chains. Hb A2 makes up a smaller portion -- about 2 percent -- of the Hb in your
body. It has two alpha and two delta protein chains. Hb F makes up 2 percent of the Hb found in
your body. It has two alpha and two gamma protein chains.
Variant Hemoglobin Types
Variants in a person's hemoglobin can occur when there are genetic changes in the globin
genes. There are four common hemoglobin variants. Hemoglobin S (Hb S) is the primary
hemoglobin in those with sickle cell disease. Hb S causes the red blood cells to deform due to
decreased amounts of oxygen, turning the red blood cells into a sickle shape. This shape
instigates blockages in the small blood vessels, causing extreme pain, reduced circulation,
decreased oxygen-carrying capacity of the red blood cells, and a decreased lifespan for the red
blood cells.