Sickle cell is a disease caused by a deformation of red blood cells. This genetic blood disease affects over 70,000 Americans, according to the Nemours Foundation. Many more are carriers who do not show symptoms but can still pass the disorder to their offspring. Because it is a genetic disease, sickle cell cannot be transmitted to others, only inherited.
Biology
Sickle cell anemia is a recessive genetic trait, meaning that it must be inherited from both parents to cause illness. If someone inherits sickle cell from only one parent, that individual will not show clinical signs of the disease, but will be a carrier, capable of passing the trait on to his children. In sickle cell disease, the oxygen-carrying compound hemoglobin is deformed, causing red blood cells to curl into a sickle shape. These deformed blood cells then become stuck in blood vessels, where they cause clots and fail to deliver oxygen to the tissues of the body. These blood cells also break down more quickly than normal red blood cells.
Clinical Traits
Individuals with sickle cell disease exhibit a range of clinical traits caused by the effects of sickle cell clumps and the lack of oxygen to bodily tissues. Anemia, a shortage of healthy red blood cells, is the primary clinical symptom of the disease. Sufferers may also experience severe pain episodes caused by sickle cells clumping together in a blood vessel, jaundice, vision problems, swelling of the hands and feet, organ damage, delayed growth in childhood and frequent infections.
Risk Factors
Individuals of African descent are most likely to have or carry the sickle cell gene. According to the Nemours Foundation, one in 12 African Americans is a carrier for sickle cell, or about 2 million people. It can also be found in individuals of Mediterranean, Middle Eastern, Latin American and Indian descent. The National Heart Lung and Blood Institute states that one in 36,000 Hispanic Americans have the disease.
Treatment
The only real cure for sickle cell disease is a bone marrow transplant. Because red blood cells are produced in the bone marrow, a transplant removes the sickle cell-producing marrow and replaces it with marrow that can provide healthy red blood cells instead. The medicine hydroxyurea is used to treat pain crises resulting from sickle cell disease, and blood transfusions are sometimes necessary to counter severe anemia stemming from the illness.
Considerations
Sickle cell anemia is a severe disease, often deadly for those who have it. However, carriers of the sickle cell trait appear to have some degree of protection from the deadly infection malaria, which is prevalent in east Africa where sickle cell originated. This protection is not total, though, since sickle cell carriers sometimes do contract malaria. However, some evolutionary biologists believe that this partial protection may account for sickle cell's high prevalence in some populations.
