Sickle cell anemia is an inherited blood disorder that causes chronic destruction of red blood cells, episodes of intense pain, vulnerability to infections, organ damage and, in some cases, early death. People with sickle cell anemia have inherited genes for a type of hemoglobin (hemoglobin S) that forms long rods when it gives up its oxygen. Red blood cells typically are disc-shaped. The long rods are located inside the red blood cells, and they stretch the red cells into sharp, abnormal "sickle" shapes.

Sickle-shaped red blood cells cannot pass through the body's blood vessels easily. Instead, they clog blood vessels, block the flow of blood, and cut off the oxygen supply to tissues and organs. This lack of oxygen can damage the body's organs and limbs, and it causes severe pain in any affected area.

Sickled blood cells last only 10 to 20 days in the bloodstream, compared with a normal red cell's lifespan of 120 days. So,sickling causes chronic anemia, abnormally low levels of red blood cells.

People with sickle cell disease also have an increased risk of developing life-threatening infections. A major reason for the increased risk of infection relates to damage to the spleen, which helps clear infections, beginning at a young age. By the time the child is 4 years old, the spleen has usually stopped functioning.

Sickle cell anemia is most common in people whose ancestors came from parts of Africa, Saudi Arabia, India and the Mediterranean region. To have a fully developed case of sickle cell anemia, one gene for the illness must be inherited from both parents.

When a person inherits only one sickle cell gene from one parent, that person is said to have sickle cell "trait" rather than sickle cell anemia. People with sickle cell trait usually have no symptoms of sickle cell anemia, but they can pass the gene for sickle cell hemoglobin to their children. Health experts estimate that approximately 2 million people in the United States currently carry the sickle cell trait.

Symptoms of sickle cell anemia include:

• Fatigue, shortness of breath, pale skin and fingernails due to the red blood cell count (anemia)
• Recurrent bouts of pain in the abdomen, chest, back, arms or legs
• A yellowing of the skin and whites of the eyes (jaundice)
• Slowed growth and delayed puberty in children
• Frequent infections
• Eye problems, including blindness
• Stroke

When sickled red cells block blood vessels, the oxygen supply to body cells is cut off, causing painful episodes called crises. Painful sickle cell crises can affect many different joints and body organs, but the back, chest, extremities and abdomen are affected most commonly. The level of pain varies, from trivial to excruciating. In about half the cases, the pain crisis is accompanied by fever, swelling, tenderness, nausea, vomiting, high blood pressure and a fast heart rate. The episodes typically last from two to seven days.

These painful episodes can be triggered by many things, such as infection, stress, alcohol consumption, menses and dehydration, but the majority of events have no identifiable cause.

Other consequences of sickle cell disease may include eye problems with vision loss, frequent infections and stroke.

Your doctor will ask you about a history of painful crises, neurological problems, chest pain and history of infections. He or she then will do a physical examination, focusing on your heart, lungs, joints, eyes and the neurological system. A blood test called a complete blood count can detect anemia, and a microscopic examination of the blood may reveal the characteristic sickled cells. Doctors diagnose sickle cell anemia by using a blood test called hemoglobin electrophoresis.

Since sickle cell anemia is an inherited disorder that is present from birth, your doctor may do a routine blood test to screen for the disorder whenever a new baby is born in your family. Prenatal screening also can be done.

Sickle cell anemia is a lifelong problem.

There is no way to prevent sickle cell anemia, although gene therapy may be possible in the future. If sickle cell anemia or sickle cell trait runs in your family, you and your spouse may wish to speak with a genetic counselor about your chances of passing a gene for sickle cell hemoglobin to your children.

Treatment of sickle cell anemia may include any of the following:

• Folic acid supplements to insure that enough of this nutrient is available to make new red blood cells
• Vaccinations for pneumococcal pneumonia, Haemophilus influenza, meningitis, hepatitis and influenza to prevent infections
• Daily antibiotic therapy to protect against infection (in young children)
• Fluids, oxygen and pain-killing medications during episodes of painful crisis
• Blood transfusions to treat anemia and painful crises
• Hydroxyurea (Hydrea) in adults � This medication seems to reduce the need for blood transfusions, while decreasing the frequency of acute chest syndrome and painful crises
• Routine eye exams to detect early abnormalities, which can be treated with laser coagulation and other types of eye surgery to prevent vision loss

Scientists are working on many new treatments that eventually may help to cure sickle cell anemia or relieve its symptoms. These include:

• Drugs that increase blood levels of fetal hemoglobin � This hemoglobin is present in all humans before birth and seems to prevent sickling of red cells.
• Gene therapy � Scientists hope to either turn off the gene for sickle hemoglobin or correct the gene and insert it into the bone marrow.

People with sickle cell disease must schedule regular doctor visits and receive comprehensive care. Call the doctor immediately when anyone with sickle cell disease develops a fever, or any other sign of infection, has severe pain in any part of their body, develops breathing problems, or develops any neurological symptoms.

Sickle cell anemia affects different people in different ways and follows no set pattern. For example, some patients have only mild symptoms with less than one crisis episode per year, while others have more severe symptoms with an average of more than one crisis per month. Although there is currently no cure for sickle cell anemia, life expectancy for those with the illness has dramatically increased over the past 30 years.

For some children with sickle cell anemia, a bone marrow transplant may cure their illness. The child has to have a sibling who is a suitable donor. However, this is a high-risk treatment that is primarily used in those with very severe symptoms.

National Heart, Lung, and Blood Institute (NHLBI)
P.O. Box 30105
Bethesda, MD 20824-0105
Phone: 301-592-8573
TTY: 240-629-3255
Fax: 301-592-8563
E-Mail: nhlbiinfo@rover.nhlbi.nih.gov
http://www.nhlbi.nih.gov/

March of Dimes Birth Defects Foundation
1275 Mamaroneck Ave.
White Plains, NY 10605
Toll-Free: 1-888-663-4637
http://www.modimes.org/

Sickle Cell Disease Association Of America
200 Corporate Pointe
Suite 495
Culver City, CA 90230-8727
Phone: 310-216-6363
Fax: 310-215-3722
Toll-Free: 1-800-421-8453
E-Mail: scdaa@sicklecelldisease.org
http://www.sicklecelldisease.org/