Sickle-Cell Disease
An inherited blood disorder that affects red blood cells. Children with sickle-cell disease have red blood cells that contain mostly “hemoglobin S,” an abnormal type of hemoglobin (the main substance in red blood cells that helps carry oxygen from the air in the lungs to the rest of the body). In sickle-cell disease, these red blood cells become abnormally shaped into a sickle, or crescent, which makes it difficult for them to pass through small blood vessels.
When sickle-shaped cells block small blood vessels, this interferes with the flow of blood to that part of the body, eventually damaging the tissue. This is what causes the complications of sickle-cell disease.
Cause
Normal red blood cells contain hemoglobin A; hemoglobin S and hemoglobin C are abnormal types of hemoglobin. Normal red blood cells are soft and round and can squeeze through tiny blood vessels and typically live for about 120 days before new ones replace them.
Children with sickle-cell conditions produce a different form of hemoglobin A, called hemoglobin S (“S” stands for sickle). Red blood cells containing hemoglobin S live only about 16 days, becoming stiff and distorted until they cannot pass through the body’s small blood vessels. When sickle-shaped cells block small blood vessels, less blood can reach that part of the body. Tissue that does not receive a normal blood flow eventually becomes damaged. This is what causes the complications of sickle-cell disease.
Types of Sickle-Cell Disease
There are several types of sickle-cell disease, but the most common are sickle-cell anemia (SS), sickle-hemoglobin C disease (SC), sickle beta-plus thalassemia, and sickle beta-zero thalassemia.
Sickle-cell trait (AS) is an inherited condition in which both hemoglobin A and S are produced in the red blood cells, although there is always more A than S. Sickle-cell trait is not a type of sickle-cell disease. People with sickle-cell trait are generally healthy.
Heredity
Sickle-cell conditions are inherited diseases. The types of hemoglobin a child produces depends on what hemoglobin genes the child inherited from both parents. Like most genes, hemoglobin genes are inherited in two sets—one from each parent. For example, if one parent has sickle-cell anemia and the other is normal, all of the children will have sickle-cell trait. If one parent has sickle-cell anemia and the other has sickle-cell trait, there is a 50 percent chance of having a baby with either sickle-cell disease or sickle-cell trait with each pregnancy. When both parents have sickle-cell trait, they have a 25 percent chance (one of four) of having a baby with sickle-cell disease with each pregnancy.
Diagnosis
A simple blood test followed by a lab technique called hemoglobin electrophoresis can determine the type of hemoglobin a child has. This technique differentiates between normal hemoglobin (A), sickle hemoglobin (S), and other different kinds of hemoglobin (such as C, D, or E).
Complications
Sickle cells are destroyed rapidly in the bodies of people with the disease causing anemia, jaundice, and gallstones. The sickle cells also block the flow of blood through vessels, resulting in lung tissue damage, pain episodes, STROKE, and priapism (painful prolonged erection). It also causes damage to most organs, including the spleen, kidneys, and liver. Damage to the spleen causes sickle-cell disease patients, (especially young children) to be easily overwhelmed by certain bacterial infections.
Treatment
Health maintenance for patients with sickle-cell disease starts with early diagnosis, preferably in the newborn period, and includes penicillin prophylaxis, vaccination against pneumococcus bacteria, and folic acid supplementation. Treatment of complications often includes antibiotics, pain management, intravenous fluids, blood transfusion, and surgery, all backed by psychosocial support. Like all patients with chronic disease patients are best managed in a comprehensive multidisciplinary program of care.
In search for a substance that can prevent red blood cells from sickling without causing harm to other parts of the body, Hydroxyurea was found to reduce the frequency of severe pain, acute chest syndrome, and the need for blood transfusions in adult patients with sickle-cell disease. Droxia, the prescription form of hydroxyurea, was approved by the Federal Drug Administration (FDA) in 1998 and is now available for adult patients with sicklecell anemia. Studies are being conducted to determine the proper dosage for children.
When sickle-shaped cells block small blood vessels, this interferes with the flow of blood to that part of the body, eventually damaging the tissue. This is what causes the complications of sickle-cell disease.
Cause
Normal red blood cells contain hemoglobin A; hemoglobin S and hemoglobin C are abnormal types of hemoglobin. Normal red blood cells are soft and round and can squeeze through tiny blood vessels and typically live for about 120 days before new ones replace them.
Children with sickle-cell conditions produce a different form of hemoglobin A, called hemoglobin S (“S” stands for sickle). Red blood cells containing hemoglobin S live only about 16 days, becoming stiff and distorted until they cannot pass through the body’s small blood vessels. When sickle-shaped cells block small blood vessels, less blood can reach that part of the body. Tissue that does not receive a normal blood flow eventually becomes damaged. This is what causes the complications of sickle-cell disease.
Types of Sickle-Cell Disease
There are several types of sickle-cell disease, but the most common are sickle-cell anemia (SS), sickle-hemoglobin C disease (SC), sickle beta-plus thalassemia, and sickle beta-zero thalassemia.
Sickle-cell trait (AS) is an inherited condition in which both hemoglobin A and S are produced in the red blood cells, although there is always more A than S. Sickle-cell trait is not a type of sickle-cell disease. People with sickle-cell trait are generally healthy.
Heredity
Sickle-cell conditions are inherited diseases. The types of hemoglobin a child produces depends on what hemoglobin genes the child inherited from both parents. Like most genes, hemoglobin genes are inherited in two sets—one from each parent. For example, if one parent has sickle-cell anemia and the other is normal, all of the children will have sickle-cell trait. If one parent has sickle-cell anemia and the other has sickle-cell trait, there is a 50 percent chance of having a baby with either sickle-cell disease or sickle-cell trait with each pregnancy. When both parents have sickle-cell trait, they have a 25 percent chance (one of four) of having a baby with sickle-cell disease with each pregnancy.
Diagnosis
A simple blood test followed by a lab technique called hemoglobin electrophoresis can determine the type of hemoglobin a child has. This technique differentiates between normal hemoglobin (A), sickle hemoglobin (S), and other different kinds of hemoglobin (such as C, D, or E).
Complications
Sickle cells are destroyed rapidly in the bodies of people with the disease causing anemia, jaundice, and gallstones. The sickle cells also block the flow of blood through vessels, resulting in lung tissue damage, pain episodes, STROKE, and priapism (painful prolonged erection). It also causes damage to most organs, including the spleen, kidneys, and liver. Damage to the spleen causes sickle-cell disease patients, (especially young children) to be easily overwhelmed by certain bacterial infections.
Treatment
Health maintenance for patients with sickle-cell disease starts with early diagnosis, preferably in the newborn period, and includes penicillin prophylaxis, vaccination against pneumococcus bacteria, and folic acid supplementation. Treatment of complications often includes antibiotics, pain management, intravenous fluids, blood transfusion, and surgery, all backed by psychosocial support. Like all patients with chronic disease patients are best managed in a comprehensive multidisciplinary program of care.
In search for a substance that can prevent red blood cells from sickling without causing harm to other parts of the body, Hydroxyurea was found to reduce the frequency of severe pain, acute chest syndrome, and the need for blood transfusions in adult patients with sickle-cell disease. Droxia, the prescription form of hydroxyurea, was approved by the Federal Drug Administration (FDA) in 1998 and is now available for adult patients with sicklecell anemia. Studies are being conducted to determine the proper dosage for children.
