People who have sickle cell disease have abnormal hemoglobin, called hemoglobin S or sickle hemoglobin, in their red blood cells. Hemoglobin is a protein in red blood cells that carries oxygen throughout the body. People who have sickle cell disease inherit two abnormal hemoglobin genes, one from each parent.
The types of sickle cell disease include the following:
In all types of sickle cell disease, at least one of the two abnormal genes causes a person’s body to make hemoglobin S. When a person has two hemoglobin S genes (hemoglobin SS), the disease is called sickle cell anemia. This is the most common and often most severe type of sickle cell disease. Hemoglobin SC disease and hemoglobin Sβ thalassemia are two other common types of sickle cell disease. Hemoglobin SD and hemoglobin SE are much less common.