Sickle cell disease is an inherited disorder in which red blood cells (RBCs) are abnormally shaped. This abnormality can result in painful episodes, serious infections, chronic anemia, and damage to body organs.
These complications can, however, vary from person to person depending on the type of sickle cell disease each has. Some people are relatively healthy and others are hospitalized frequently.
But thanks to advancements in early diagnosis and treatment, most kids born with this disorder grow up to live relatively healthy and productive lives.
A Closer Look at Sickle Cell Disease
The different forms of sickle cell disease are determined by the genes inherited from the person's parents.
Someone who has the disease has inherited a sickle cell gene from each parent (hemoglobin SS disease, also called sickle cell anemia).
A person can also inherit a sickle cell gene from one parent and a different kind of abnormal gene from the other and end up with a different form of sickle cell disease, such as hemoglobin SC disease or hemoglobin S-thalassemia.
Someone who inherits only one sickle cell gene and a normal gene from the other parent will have the sickle cell trait, but not the disease. A blood test can determine whether you have sickle cell disease or carry the sickle cell trait.
People with sickle cell trait don't have sickle cell disease or exhibit any signs of the disorder, but they can pass the gene for the disease to their children. When both parents have the sickle cell trait, there's a 25% chance that a child will have sickle cell disease. But when one parent is carrying the trait and the other actually has the disease, the odds increase to 50% that their child will inherit the disease.
Who Is Affected?
In the United States, hemoglobin SS disease (sickle cell anemia) affects mostly African Americans. Some forms of sickle cell disease may occur, although less frequently, in people with different ethnic backgrounds, such as those whose ancestors came from Mediterranean countries (including Turkey, Greece, and Italy), East India, or Middle Eastern countries.
Causes of Sickle Cell Disease
A child with sickle cell disease has inherited two defective hemoglobin genes. The hemoglobin can take on an abnormal shape, distorting the shape of the red blood cell. The cells change from a normal round, doughnut shape to the elongated shape of a sickle, or the shape of the letter "C."
Unlike normal RBCs, which move easily through small blood vessels, sickle cells are stiff and pointed. The sickle shape means that they have a tendency to get stuck in narrow blood vessels and block the flow of blood. This can cause episodes of pain and can also lead to organ damage because the cells aren't getting enough oxygen.
Sickle cells have a shorter-than-normal life span, which leads to anemia (low red blood cell count). A normal red blood cell lives for about 120 days, whereas a sickle cell lives for only 10 to 20 days.
Diagnosis
Usually, sickle cell disease is diagnosed at birth with a blood test. This can be done in conjunction with other routine newborn screening tests. If a child tests positive on the screening test, a second blood test is usually performed to confirm the diagnosis.
Because kids with sickle cell disease are at an increased risk of infection and other health complications, early diagnosis and treatment is important. Currently, more than 40 states require newborn screening programs for sickle cell disease.
Signs and Symptoms
Symptoms of sickle cell disease vary and range from mild to severe, and symptoms may be less severe or different in children who have inherited a sickle cell gene from one parent and a different abnormal hemoglobin gene from the other.
Most kids with sickle cell disease have some degree of anemia and might develop one or more of the following conditions and symptoms as part of the disorder:
Acute chest syndrome: Inflammation or trapped red blood cells in the lungs cause this syndrome. Signs include chest pain, coughing, difficulty breathing, and fever.
Aplastic crisis: This is when the bone marrow temporarily slows its production of RBCs due to infection or another cause, resulting in a severe drop in the red cell count and severe anemia. Signs include paleness, fatigue, and rapid pulse.
Hand-foot syndrome (also called dactylitis): This painful swelling of the hands and feet, plus fever, may be the first sign of sickle cell anemia in some infants.
Infection: Kids with sickle cell disease are at increased risk for certain bacterial infections. It's important to watch for fevers of 101° Fahrenheit (38° Celsius) or higher, which could signal an infection. Children with sickle cell disease and fever should be seen by a doctor immediately.
Painful crises: These may occur in any part of the body and may be brought on by cold or dehydration. The pain may last a few hours or up to 2 weeks or even longer, and may be so severe that a child needs to be hospitalized.
Splenic sequestration crises: The spleen becomes enlarged by trapping (or "sequestering") the abnormal RBCs. This leads to fewer cells in the general circulation. Early signs include paleness, weakness, an enlarged spleen, and pain in the abdomen.
Stroke: Poor blood flow in the brain can occur when the sickle-shaped cells block small blood vessels. This may lead to a stroke. Signs can include headache, seizures, weakness of the arms and legs, speech problems, a facial droop, and loss of consciousness.
Other possible complications include leg ulcers, bone or joint damage, gallstones, kidney damage, painful prolonged erections in males (priapism), eye damage, and delayed growth.
Treatment
Aside from a bone marrow transplant, there is no known cure for sickle cell disease. Transplants are complicated procedures and aren't an option for everyone. To qualify, a child would need bone marrow from a "matched" donor with a low risk of being rejected. Even then, there are significant risks to the procedure and there's always the chance of rejection of the transplanted marrow.
But even without a cure, kids with sickle cell disease can lead relatively normal lives. Medicines are available to help manage the pain, and immunizations and daily doses of penicillin (an antibiotic) can help prevent infection.
Infection used to cause many deaths in infants with sickle cell disease, but thanks to penicillin and appropriate immunizations, children with sickle cell disease are much more likely to live longer, healthier lives. Although penicillin isn't a cure, it can help prevent life-threatening infections due to bacteria that cause serious infections such as sepsis (a severe infection in the blood), meningitis, and pneumonia.
Infants and kids with sickle cell disease usually require two daily doses of penicillin, as prescribed by their doctors, until they're at least 5 years old (and often older). In addition, they should be fully immunized with the regular childhood vaccinations, including the pneumococcal vaccine and influenza and meningococcal vaccines.
Most doctors also prescribe daily vitamin supplements. Folic acid, in particular, can help a child with the disorder produce new RBCs.
In addition, kids who develop serious complications (such as acute chest syndrome, severe anemia, or stroke) may receive regular transfusions of red blood cells to prevent or treat these complications.
In 1998 the U.S. Food and Drug Administration (FDA) approved the drug hydroxyurea for use in adults with sickle cell disease; while it still has not been officially approved for use in children, it can be used by specialists in some circumstances.
Hydroxyurea increases the amount of fetal hemoglobin in blood cells, which interferes with the sickling process and makes red blood cells less sticky. This helps decrease the number and intensity of painful episodes and other complications. The drug has been proven to decrease pain and other complications in children as well as adults. Research is continuing to determine the drug's long-term effects and safety.
When to Call the Doctor
Seek emergency medical attention immediately if your child develops any of the following:
- fever of 101° Fahrenheit (38° Celsius) or higher
- pain that isn't relieved by oral medication
- chest pain
- shortness of breath or trouble breathing
- severe headaches or dizziness
- severe stomach pain or swelling
- jaundice or extreme paleness
- painful erection in males
- sudden change in vision
- seizures
- weakness or inability to move any part of the body
- loss of consciousness
Caring for Your Child
In addition to the primary care doctor, your child should receive regular care from a hematologist (a blood specialist) or a sickle cell specialty clinic. It's important to share your concerns and discuss any new symptoms or complications with your child's health care team.
Your child also should drink lots of fluids, get plenty of rest, and avoid extreme temperatures.
Most people with sickle cell disease now live into their mid-40s and beyond. A critical time is the first few years of life, which is why early diagnosis and treatment are so important.
Reviewed by: James Fahner, MD
Date reviewed: June 2007
Originally reviewed by: Steven Dowshen, MD, and Barbara P. Homeier, MD
