Sickle cell anemia is an inherited blood disorder. It affects the red blood cells, resulting in pain and a number of other complications. The disease is present at birth, and symptoms typically begin early in childhood. Studies have indicated that 96 percent of children who were diagnosed with sickle cell anemia at birth have experienced symptoms by eight years of age. According to the Sickle Cell Disease Association of America, there are approximately 1,000 babies born with the disease each year and more than 70,000 people living with the disease in the United States. Although complications such as infection and organ damage can be fatal, most patients with sickle cell anemia live into their 40s and 50s, whereas, in the past, the life expectancy was often between 20 and 40.

Diseases caused by sickle cell trait caused damage in two ways. First, patients suffer from vasoocclusive events. This means that the abnormally shaped blood cells block vessels in the body. There is some controversy about why the sickle-shaped cells provoke these events. Whatever the reason, during a vasoocclusive event, the flow of blood is restricted to the tissues beyond the blocked area. This can result in bouts of acute, intense pain. Oftentimes, this is the first symptom of sickle cell anemia, especially in the hands and feet.

Second, sickle cell diseases result in a shortage of red blood cells in the blood, a condition known as anemia. A normal red blood cell survives for about 90 days. A sickle-shaped blood cell, however, may survive for only 16 days before it is destroyed. Thus, the blood's overall oxygen-carrying capacity is reduced and the number of red blood cells is depressed.

Red blood cells are produced in the bone marrow, the soft inner component of bones. They contain hemoglobin, an iron-rich protein molecule that picks up oxygen from the lungs and releases it to the tissues as blood travels through the body. In healthy individuals, the body produces normal hemoglobin (hemoglobin A). In people with sickle cell anemia, red blood cells mostly contain an abnormal form of hemoglobin known as hemoglobin S. Hemoglobin S reduces the amount of oxygen in the cells.

In addition, there are other sickle cell diseases (SCDs), or hemoglobinopathies, in which symptoms may resemble those of sickle cell anemia but are generally milder. These related disorders include hemoglobin C disease, hemoglobin SC disease, sickle beta-plus thalassemia and sickle beta-zero thalassemia. The National Institutes of Health says that SCD is the nation’s most common inherited blood disorder.