SCD is an inherited blood disorder that affects red blood cells. Red blood cells contain hemoglobin which allows red blood cells to carry oxygen from the air in the lungs to all parts of the body.
Normal red blood cells contain hemoglobin A. In contrast, the bone marrow of people with SCD produces red blood cells with a different form of hemoglobin called hemoglobin S (S stands for sickle). When a person has SCD, rather than remaining round, smooth and flexible, the red blood cells become sickle (crescent) shaped, inflexible, and sticky as they release oxygen to other tissues in the body.
Normal red blood cells live for about 120 days before they are replaced with new ones. In sharp contrast, sickle-shaped red blood cells are destroyed faster, in about 16 days, and cannot always be replaced quickly enough. As a result people with SCD are often anemic. The complications of sickle cell disease occur when sickle-shaped red blood cells block veins which then can cause pain in the arms, legs, back and stomach, bones, skin and other parts of the body. Tissue that does not receive normal blood flow eventually becomes damaged.
Currently there is no universal cure for sickle cell disease.
Types of Sickle Cell Disease
There are several types of sickle cell disease. The most common are:
- Sickle Cell Anemia (SS)
- Sickle-Hemoglobin C Disease (SC)
- Sickle β+-thalassemia and Sickle β°-thalassemia
Center for Disease Control and Prevention, Hemoglobin S Allele and Sickle Cell Disease, an excellent article about sickle cell genetics and epidemiology
The Sickle Cell Information Center, a broad range of information for the public and professionals
National Organization for Rare Disorders, Inc., a portal for all rare diseases
ClinicalTrials.gov, linking patients to medical research, a search engine for clinical trials in different diseases
The Management of Sickle Cell Disease, National Institutes of Health, National Heart, Lung, and Blood Institute