Sickle-Cell Disease

Video of Sickle-Cell Disease

Diagram of normal and sickle red blood cell

Sickle-cell disease (SCD) contains Hb-S, an abnormal kind of hemoglobin. When Hb-S gives up oxygen to the interstitial fluid, it forms long and rod-like structures that bend the erythrocyte into a sickle shape. This abnormality can result in painful episodes, serious infections, chronic anemia, and damage to body organs. The sickled cells can rupture easily. Even though erythropoiesis is stimulated by the loss of the cells, it cannot keep pace with hemolysis. Sickle-cell disease is inherited. People with two sickle-cell genes have severe anemia. The gene responsible for the tendency of the RBCs to sickle also alters the permeability of the plasma membranes of sickled cells, causing potassium ions to leak out. Low levels of potassium kill the malaria parasites that may infect sickled cells. Thus, a person with one normal gene and one sickle-cell gene has higher-than-average resistance to malaria. Sickle-cell disease is inherited. People with two sickle-cell genes have severe anemia; those with only one defective gene have minor problems.
Treatment of sickle-cell disease consists of administration of analgesics to relieve pain, fluid therapy to maintain hydration, oxygen to reduce the possibility of oxygen debt and blood transfusions. People who suffer from SCD have normal fetal predominates bin, a slightly different form of hemoglobin that predominates at birth and is present in small amounts thereafter. In some patients with sickle-cell disease, a drug called hydroxyurea promotes transcription of the normal Hb-F gene, elevates the level of Hb-F, and reduces the chance that the RBCs will sickle. Unfortunately, this drug also has toxic effects on the bone marrow. Thus, its safety for long term use is questionable. 

 Source: http://www.youtube.com/watch?v=9UpwV1tdxcs