Sickle Cell Disease (page 2)
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 inherits a sickle cell gene from each parent has 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 beta 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 someone has a form of sickle cell disease or carries the sickle cell trait.
People with sickle cell trait don't have sickle cell disease and usually don't exhibit signs of the disorder, but they can pass the gene for the disease to their children. Many people don't know they have sickle cell trait, but most babies in the United States are now tested as part of their newborn screening. 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. However, forms of sickle cell disease may occur 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
Hemoglobin allows red blood cells to carry oxygen. It is made up of alpha chains and beta chains. A child with sickle cell disease has inherited two defective genes for the beta chain of hemoglobin.
The hemoglobin can take on an abnormal shape, distorting the shape of RBCs. 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. 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 tissues aren't getting enough oxygen.
Sickle cells have a shorter-than-normal life span, which leads to anemia (low RBC count). A normal red blood cell lives for about 120 days in circulation, whereas a sickle cell lives for only 10 to 20 days.
Sickle cell disease usually is diagnosed at birth with a blood test during routine newborn screening tests. If a child tests positive on the screening test, a second blood test (called a hemoglobin electrophoresis) should be 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 to prevent problems is important. Currently, more than 40 states require newborn screening programs for sickle cell disease.
Signs and Symptoms
Symptoms of sickle cell disease vary, ranging from mild to severe, and may be less severe or different in kids 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, infection, and occlusion of small vessels may 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 serious drop in RBCs and severe anemia. Signs include paleness, fatigue, and rapid pulse.
Hand-foot syndrome (also called dactylitis): This painful swelling of the hands and feet 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 101ºF (38ºC) 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, a few days, or sometimes much longer. Pain 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 can lead to a serious and rapid drop in the red cell count (severe anemia). Early signs include paleness, weakness or fatigue, an enlarged spleen, and pain in the abdomen.
Stroke: Impaired blood flow in the brain can occur when the sickle-shaped cells block small blood vessels, which may lead to a stroke. Signs can include headache, seizures, weakness of the arms and legs, speech problems, a facial droop, or 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.
Note: All information is for educational purposes only. For specific medical advice, diagnoses, and treatment, consult your doctor.
© 1995-2009 The Nemours Foundation. All rights reserved.
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