Sickle cell anemia is caused by a defect in the gene that controls the production of normal hemoglobin, which is an iron-containing protein in red blood cells that transports oxygen from the lungs to body tissues. The defective gene results in the production of abnormal hemoglobin known as hemoglobin S. If you have the disorder, you inherited one gene for hemoglobin S from each of your parents. The gene is recessive, so if you received a copy of the gene from just one parent, you are a carrier of the sickle cell gene.Under certain conditions, after hemoglobin S releases its oxygen, its molecules clump together forming rigid and elongated crystals. The crystals settle to one side of the cell, which collapses the other side. These red blood cells, which normally look like miniature inner tubes, become stiff and distorted in appearance. Some cells take on the shape of a crescent or farmer's sickle, while others may resemble teardrops or stars. These misshapen cells stick to each other, and because of a chemical on their surface, they also stick the vessel walls. In the capillaries, the sticky, rigid, odd-shaped cells create a logjam. This causes a block in blood flow and deprives body tissues of their necessary oxygen. Without oxygen, cells begin to die and tissues suffer damage. These episodes are painful for the patient, but they are not permanent. Sickled red cells eventually regain their normal round shape when they are re-oxygenated and re-hydrated. Sickling can be triggered whenever the rate of blood flow is reduced, or when the body's supply of water or oxygen decreased. Some causes of sickling are dehydration, cold temperatures, a change in available oxygen or air pressure, and fever or a viral infection.Symptoms of the sickle cell anemia appear at about six months of age. Symptoms may be enlargement of the abdomen and heart, painful swelling of the hands and feet, anemia, aplastic crisis, acute chest syndrome, infections, sple...
