The Sickle cell anemia is caused by an abnormal type of hemoglobin called hemoglobin S. Hemoglobin is a protein inside red blood cells that carries oxygen. Hemoglobin S, however, distorts the red blood cells' shape. The fragile, sickle-shaped cells deliver less oxygen to the body's tissues, and can break into pieces that disrupt blood flow. Sickle cell anemia is inherited as an autosomal recessive trait. This means it occurs in someone who has inherited hemoglobin S from both parents. Sickle cell disease is much more common in certain ethnic groups, affecting approximately one out of every 500 African Americans. Someone who inherits hemoglobin S from one parent and normal hemoglobin (A) from the other parent will have sickle cell trait. Patients with sickle cell disease need continuous treatment, even when they are not having a painful crisis. Supplementation with folic acid, an essential element in producing red blood cells, is required because of the rapid red blood cell turnover. The purpose of treatment is to manage and control symptoms, and to try to limit the frequency of crises. During a sickle crisis, certain treatments may be necessary. Painful episodes are treated with analgesics and enough liquid intake. Treatment of pain is critical. Non-narcotic medications may be effective, but some patients will require narcotics. Bone marrow transplants can cure the disease, but it is only recommended in a minority of patients. This is mostly due to the high risk of the procedure (the drugs needed to make the transplant possible are highly toxic) and the difficulty in finding suitable donors. Also, bone marrow transplants are much more expensive than other treatments. Antibiotics and vaccines are given to prevent bacterial infections, which are common in children with sickle cell disease.