What is sickle cell disease?

Sickle cell disease is an inherited blood disorder that affects the red blood cells.  People with sickle cell disease have red blood cells that contain mostly sickle hemoglobin (S), instead of normal hemoglobin (A).(Hemoglobin is the substance in red blood cells that carries oxygen throughout the body.)  Sometimes, in a person with sickle cell disease (SS) the red blood cells sickle (become crescent shaped) and have difficulty passing through small blood vessels.  When sickle cells block small blood vessels, less blood can reach that part of the body. Tissue that does not receive normal blood flow eventually becomes damaged. This is what causes the complications of sickle cell disease.

What is sickle cell trait?

Sickle cell trait is the benign carrier state of sickle cell disease. Individuals with trait do not have any symptoms of the disease, but they can have children with the trait or disease.

What is the difference between sickle cell disease and trait?

People with sickle cell trait (AS) inherit one gene for normal hemoglobin (A) and one gene for sickle hemoglobin (S) from their parents. Because they have one (A) gene, individuals with trait do not have any medical problems, but they can pass the (S) gene to their children. People with sickle cell disease (SS) inherit two genes for sickle hemoglobin (S) from their parents. They have symptoms because their red blood cells do not make normal hemoglobin.

How do you get sickle cell?

Sickle cell disease and trait are inherited – they are passed from parents to children, like hair color or skin color. Sickle cell is not contagious – it can’t be caught like a cold or flu. People with sickle cell trait or disease are born with it, and will have it their whole lives. Sickle cell trait will never turn into disease. The genes that determine whether or not your blood cells will sickle are yours from birth and will never change.

Sickle cell trait (AS) is inherited when one parent contributes a gene for normal hemoglobin (A) and the other parent contributes a gene for sickle hemoglobin (S). If a person with trait and a person with normal hemoglobin have a child (AS + AA), there is a 50% chance the child will be born with trait (AS) and a 50% chance the child will have normal hemoglobin (AA). They cannot have a child with disease. However, if two people with trait have a child (AS + AS), there is a 25% chance the child will have normal hemoglobin (AA), a 50% chance the child will have trait (AS), and a 25% chance the child will have disease (SS). Even if two people with trait have had several children that do not have sickle cell, they can still have a child that is born with the disease.

How do I know if I have sickle cell trait or disease?

The only way to know if you have sickle cell trait or disease is to be tested. In most states in the United States, this blood test is part of routine newborn screening done at the hospital, but older children and adults can be tested too. In adults, a blood sample is drawn from a vein in the arm. In young children and babies, the blood sample is usually collected from a finger or heel. The sample is then sent to a laboratory, where a technician can screen for sickle hemoglobin (S). If the screening test is negative, there is no sickle cell gene present. If the screening test is positive, the technician will conduct further tests to determine whether one or two sickle cell genes are present. The NASCFI offers free screening for sickle cell disease and trait from 8:00 a.m. to 5:00 p.m., Monday through Friday. If you are interested in being tested, no appointment is necessary, but it’s a good idea to call first.

Will a person with sickle cell trait experience medical problems?

Most people with sickle cell trait (AS) do not experience any medical problems due to their carrier status. A few people with trait may have symptoms, although this is very rare. These can include: blood in the urine, pain or discomfort at high altitudes, and problems with extreme exercise in hot, humid weather when not drinking enough water.

What are the signs and symptoms of sickle cell disease?

The complications experienced by individuals with sickle cell disease and the severity of the symptoms vary from person to person. Pain is the most common symptom experienced by people with sickle cell disease. Other common complications include:

Anemia –Normal red blood cells live for about 120 days. Sickle cells are fragile and only live for 10-20 days, and the body cannot make enough new cells to compensate. This leaves people with sickle cell disease chronically short on red blood cells to carry oxygen to their tissues. This condition is known as anemia. Anemia causes fatigue because without enough red blood cells in circulation, the body can’t get the oxygen it needs to feel energized.

Pain Crises –Periodic episodes of pain, called crises, are a major symptom of sickle cell anemia. Pain develops when sickle red blood cells block blood flow through tiny blood vessels. The pain may vary in intensity and can last from a few hours to a few weeks. Some people experience infrequent episodes of pain. Others experience a dozen or more crises a year. Pain crises can be triggered by emotional upset or stress, dehydration, overexposure to heat or cold, tiredness, smoking, overexertion, high altitudes, infection, or can happen for no apparent reason. To help prevent pain crises, people with sickle cell disease should eat nutritiously, drink plenty of water, enjoy physical activities, follow all doctor’s instructions, and avoid smoking, caffeine and other triggers. If a crisis is severe enough, hospitalization may be required.

Hand-Foot Syndrome (Dactylitis) –Swollen hands and feet are often the first signs of sickle cell anemia in babies. The swelling is caused by sickle red blood cells blocking blood flow from the hands and feet. (Babies with sickle cell disease usually don’t have any symptoms before 3 – 6 months of age.)

Jaundice–Jaundice is a yellowing of the skin and eyes that occurs because of liver damage or dysfunction. People who have sickle cell anemia often have some degree of jaundice because the liver, which filters harmful substances from the blood, is overwhelmed by the rapid breakdown of red blood cells.

Frequent Infections –Sickle cells can damage the spleen, an organ that fights infection. This makes people with sickle cell disease more vulnerable to infection. Doctors commonly give infants and children with sickle cell anemia antibiotics to prevent potentially life-threatening infections, such as pneumonia.

Stunted Growth –Red blood cells provide the body with the oxygen and nutrients it needs for growth. A shortage of healthy red blood cells can slow growth and delay puberty.

Other complications that can affect people with sickle cell disease include: stroke, acute chest syndrome, splenic sequestration (blood is trapped in the spleen), priapism (non-sexual prolonged painful erection), complications during pregnancy, organ damage, vision problems, skin ulcers, gallstones, bone necrosis, and even death.

Are there different types of sickle cell disease and trait?

There are several variants of sickle cell trait and disease, and all are due to the inheritance of genes for an abnormal type of hemoglobin, instead of normal hemoglobin (A). Some of the most common abnormal hemoglobin traits are:

- Sickle Cell Trait (AS) - Hemoglobin C Trait (AC) - Hemoglobin D Trait (AD) - Hemoglobin E Trait (AE) - Alpha Thalassemia Trait - Beta Thalassemia Trait

When two people with abnormal hemoglobin traits have a child, their genes can combine in different ways. Below are some of the forms of sickle cell disease:

- Sickle Cell Anemia (SS) - Sickle Hemoglobin C Disease (SC) - Sickle Hemoglobin D Disease (SD) - Hemoglobin C Disease (CC) - Sickle Beta Thalassemia Disease

How is sickle cell disease treated?

Bone marrow transplant offers the only potential cure for sickle cell anemia. However, very few people have a suitable donor for transplant, and the procedure is risky. As a result, treatment for sickle cell anemia is usually aimed at avoiding crises, relieving symptoms, and preventing and treating complications. People with sickle cell disease need to visit their doctor regularly. They may also require treatment from specialists at a hospital or sickle cell clinic. Below are some of the ways sickle cell is treated:

Treating Complications –Doctors treat most complications of sickle cell anemia as they occur. Treatment may include antibiotics, blood transfusions, pain-relieving medicines, other medications, and possibly surgery, such as to correct vision problems or to remove a damaged spleen.

Antibiotics –Children with sickle cell anemia usually take the antibiotic penicillin from the age of 2 months to 5 years. Doing so helps prevent infections, such as pneumonia, which can be life-threatening to an infant or child with sickle cell anemia. Antibiotics may also help adults with sickle cell anemia fight certain infections.

Pain-Relieving Medications –To relieve pain during a sickle crisis, doctors may advise over-the-counter pain relievers and application of heat to the affected area. For more severe pain, doctors often prescribe stronger pain relieving medication.

Hydroxyurea (Droxia, Hydrea) –This prescription drug, first used to treat cancer, may be helpful for adults with severe disease symptoms. When taken daily, it reduces the frequency of painful crises and may reduce the need for blood transfusions. It works by stimulating production of fetal hemoglobin — a type of hemoglobin found in newborns that helps prevent the formation of sickle cells.

Blood Transfusions –In a red blood cell transfusion, donated cells are given intravenously to a person with sickle cell anemia. Blood transfusions increase the number of normal red blood cells in circulation, helping to relieve anemia. In children with sickle cell anemia at high risk of stroke, regular blood transfusions can decrease their risk of stroke. Blood transfusions carry some risk. Regular blood transfusions cause an excess amount of iron to build up in the body. Because excess iron can damage the heart, liver, and other organs, people who undergo regular transfusions must often receive treatment to reduce iron levels.

Bone Marrow Transplant –This procedure allows people with sickle cell anemia to replace their bone marrow — and its sickle red blood cells — with healthy bone marrow from a donor who doesn’t have the disease. It can be a cure, but the procedure is risky, and it’s difficult to find suitable donors. Researchers are still studying bone marrow transplants for people with sickle cell anemia. Currently, the procedure is recommended only for people who have significant symptoms and problems from sickle cell anemia. In a bone marrow transplant, the bone marrow is first destroyed using chemotherapy or radiation. A matched donor’s healthy bone marrow is transplanted, and, ideally, begins producing normal blood cells. Sometimes, however, the transplant doesn’t work or the recipient’s body rejects the new marrow. The procedure requires a lengthy hospital stay. After the transplant, medication is given to help prevent rejection of the donated marrow.

Is there a cure for sickle cell?

A universal cure for sickle cell has not yet been discovered. Bone marrow transplants have cured sickle cell in some individuals, but the procedure is risky and has a high chance of failure. Many doctors believe that the research currently being done on gene therapy is the first step in finding a viable cure for sickle cell disease.