Sickle cell disease is a group of inherited red blood cell disorders. Healthy, doughnut-shaped red blood cells are soft and flexible. They flow easily through small blood vessels. They contain normal hemoglobin A, a protein that attaches to oxygen. These healthy red blood cells carry this oxygen to tissues throughout the body.
In a person with sickle cell disease, red blood cells contain abnormal hemoglobin molecules, called hemoglobin S (sickle). These red blood cells become hard and sticky and take on the shape of a “C”. They look like the farmers’ tool called a sickle.
Sickle cells don't live as long as healthy red blood cells. This causes a shortage of the cells, or anemia. When sickle cells travel through small blood vessels, they can get stuck and clog the blood flow. This causes pain episodes called sickle cell pain crises, often in the arms, legs, chest, back or abdomen. Constant sickling also causes blood vessel damage and injuries to the body's organs.
Sickle cell anemia occurs most frequently in the African-American population, and less frequently in Hispanic and Middle Eastern populations. There are about 70,000 to 100,000 people with sickle cell disease in the United States.
One out of 12, or about 10 percent, of African-Americans have the sickle cell trait. When both parents carry the trait, their child has a one in four chance of being born with sickle cell disease. People with sickle cell trait do not have symptoms and lead a normal life.
There are several forms of sickle cell disease. The most common is Hemoglobin SS disease, in which the patient carries two copies of the abnormal hemoglobin S gene. The second-most common is Hemoglobin SC disease, in which the patient has one copy of hemoglobin S and one copy of hemoglobin C. Another type of sickle cell disease, sickle/beta-thalassemia, has one copy of hemoglobin S and one copy of hemoglobin A that does not work normally.
A genetic counselor or hematologist can help you understand how the different forms of sickle cell disease are inherited and the risks of having a child with sickle cell disease.
This symptom of sickle cell disease usually occurs in babies. It can be the first symptom of sickle cell disease. Sickle cells clogging blood vessels or the marrow in the small bones of the hands and feet cause swelling and fever. Treatment includes pain medication and fluids.
This is the most common complication of sickle cell disease. It is the most frequent reason people with sickle cell disease go to the emergency room or are admitted to the hospital. Sickle cell pain comes from sickle cells clogging the blood flow of small vessels. The pain can start suddenly. It can be mild or severe, and can last for a short time or several days. Sickle cell pain is treated with pain medication and hydration, at home or in the hospital.
The medication Hydroxyurea prevents sickle cell pain crisis.
Sickle cells blocking blood flow in the lungs, usually when there is also a lung infection, causes chest pain, fluid buildup in the chest and insufficient oxygen delivery. This is called acute chest syndrome. Treatment includes antibiotics, giving extra oxygen through a mask, blood transfusion and pain medication.
Hydroxyurea can reduce the frequency and severity of acute chest syndrome.
Damage to blood vessels in the brain increases the chances for sickle cells to block flow. When brains cells do not get enough oxygen, they may die, causing abnormal function in some parts of the body. This is more commonly known as a stroke. Patients who experience a stroke are treated with scheduled, long-term blood transfusions to prevent another stroke.
A test called transcranial doppler ultrasound (TCD) measures the velocity of blood flow in the brain's large arteries and identifies children who are at increased risk for stroke. A chronic blood transfusion program or hydroxyurea therapy is offered to children who have abnormal TCDs.
Sickle cell disease symptoms can be avoided by preventing red blood cells from becoming sickle-shaped. Ways to help sickle cells stay round include:
The only known cure for sickle cell disease is bone marrow or stem cell transplant. Bone marrow is the soft tissue inside the bones that makes blood cells. In a bone marrow transplant, a doctor takes healthy bone marrow cells from a person who does not have sickle cell disease (the donor) and gives them to the person who has sickle cell disease (the recipient) to replace the bone marrow that is making sickle cells.
Bone marrow transplantation is a major procedure. It can cause serious side effects. Bone marrow transplantation for sickle cell disease has become safer for children as doctors have learned more about this treatment and the disease. It is an option for some children under the right circumstances.
For the transplant to work, the bone marrow must come from someone who is a close match, usually a healthy sibling who has the same set of parents as the child with sickle cell disease. The pediatric bone marrow transplant team at Vanderbilt has successfully performed transplants on many children with sickle cell disease. We continue to offer this option to children with appropriate sibling donors.
To learn more about bone marrow transplantation for sickle cell disease, please contact a member of the Sickle Cell Disease Center of Excellence at (615) 340-1280 or the Pediatric Stem Cell Transplant and Cellular Therapy Program at (615) 936-1762.
Hydroxyurea is a medication that can help many sickle cell patients. It does not cure sickle cell disease, but it can improve many symptoms, by:
Read more about hydroxyurea treatment for children with sickle cell disease.