The Painful FAQ’s about Sickle Cell
Sickle Cell Disease (SCD) is an inherited condition characterized by the presence of abnormal hemoglobin, hemoglobin S or sickled hemoglobin, in a person’s red blood cells.Hemoglobin is a protein found in red blood cells that is responsible for transporting oxygen to cells in tissues throughout the body. Red blood cells containing normal hemoglobin are disc-shaped and flexible, allowing them to travel easily through large and small blood vessels to deliver oxygen to the cells. However, hemoglobin S is crescent or sickle shaped with a rigid, sticky texture, which may cause the blood cells to get stuck to vessel walls, hindering or blocking blood flow, and ultimately, the necessary amount of oxygen to be supplied to the cells.Each person has two hemoglobin genes in every cell of their body, except the eggs and sperm. A person with two normal hemoglobin genes has neither SCD nor the sickle cell trait. A person is said to have the sickle cell trait if he/she inherits one normal hemoglobin gene from one parent, and one hemoglobin S gene from the other. In order for someone to have the disease, he or she must inherit two hemoglobin S genes – one from either parent. Since SCD is a genetic condition that can only be inherited from a person’s parents, it is not contagious and cannot be contracted through physical contact.
Sickle cell disease and thalassemia are genetic disorders caused by errors in the genes for hemoglobin, a substance composed of a protein (“globin”) plus an iron molecule (“heme”) that is responsible for carrying oxygen within the red blood cell. These disorders can cause fatigue, jaundice, and episodes of pain ranging from mild to very severe. They are inherited, and usually both parents must pass on an abnormal gene in order for a child to have the disease. When this happens, the resulting diseases are serious and, at times, fatal.Thalassemia, or Mediterranean anemia, was first described in 1925 by a Detroit physician who studied Italian children with severe anemia (low levels of red blood cells), poor growth, huge abdominal organs, and early childhood death. In 1946, the cause of thalassemia was found to be an abnormal hemoglobin structure. The body reacts by destroying red blood cells, causing anemia. To compensate for the loss, the body tries to make red blood cells more rapidly, causing other thalassemia complications, such as bone abnormalities and spleen enlargement.In the 1960s, doctors treating thalassemia patients started to transfuse them with fresh red blood cells every month. This alleviated most of the childhood symptoms and led to a major improvement in survival. It is still used as a treatment today. However, since blood contains large amounts of iron, which the body cannot eliminate naturally, most patients died in their teenage years from damage caused by too much iron. Researchers later found that excess iron could be removed from the body by treatment with a drug called desferoxamine. This drug prevented iron-induced heart disease and helped patients live much longer. Recently, two oral drugs have become available to remove iron. They have dramatically improved the quality of life of patients with iron overload from transfusions for thalassemia. Furthermore, specialized imaging tests can now find iron in the heart and allow patients to be treated before they develop iron-related heart failure.As with sickle cell disease, drugs that increase production of fetal hemoglobin can partially correct the anemia of thalassemia, but efforts to improve the treatment of thalassemia continue.
Hemoglobin S genes are inherited from parents. Each parent has one normal hemoglobin gene (A) and one sickled hemoglobin gene (S). There are four possible combinations of these genes, and three potential outcomes:• The child inherits two normal genes from either parent – AA (25% probability) • The child inherits one normal gene from the mother and one abnormal gene from the father – AS (25% probability) • The child inherits one abnormal gene from mother and one normal gene from the father – AS (25% probability) • The child inherits two abnormal genes from either parent (25% probability)This means that a child has a 25% chance of being born without the disease, 50% chance of being born with the trait, and 25% of being born with the disease. These probabilities remain the same for each child born to these parents, and do not vary across gender.
According to the Centers for Disease Control and Prevention, millions of people across the world are affected by SCD. It is most commonly found in people whose ancestors originate from sub-Saharan Africa; Spanish-speaking regions in the Western Hemisphere, including South America, the Caribbean, and Central America; Saudi Arabia, India, and Mediterranean countries, such as Turkey, Greece and Italy. Although most common amongst those of African descent, it is important to note that SCD is NOT a “Black disease.”
Sickle Cell Disease is diagnosed through performing tests that: • Identify the presence of hemoglobin S • Determine the status and number of red blood cells • Evaluate the hemoglobin level • Determine if only one or more hemoglobin S gene copies
There are several ways to test for the presence of hemoglobin S in a person’s blood. Testing can be done at almost any stage of a person’s life, including 8-10 weeks after conception. Types of tests include Screening Tests, Newborn Screening and Prenatal Screening. It is important for people to learn if they carry the hemoglobin S gene that they may pass to a child. Knowing allows people to make informed decisions when family planning. Screening Tests
Screenings can be performed on anyone who was not screened for the sickle cell trait or disease at birth. The Hemoglobin S solubility test and sodium metabisulfite test involve adding certain chemicals to a patient’s blood sample to reduce the amount of oxygen present. This causes the abnormal hemoglobin cells (hemoglobin S) to form; however, it does not distinguish between whether or not a person has sickle cell trait or SCD. Further testing needs to be conducted to make a diagnosis. It is also important to note that these tests may provide a false negative if administered on a baby too early. Therefore, it is best to consult a specialist to advise how early this testing can be done or consider performing one of the other types of testing as it is relevant to the situation. Prenatal Screening
Prenatal screening requires genetic testing methods, and can be done as early as 8-10 weeks after becoming pregnant, depending on the employed method of testing. Methods include:
- Chorionic Villus Sampling (CVS) can be performed around week 9 or 10 of pregnancy. A small amount of tissue is taken from the placenta, the organ connecting the developing baby to the mother’s uterus, to test for the genetic disorder.
- Amniocentesis can be performed between 16 and 18 weeks of pregnancy. This testing is done by using a sample of amniotic fluid, which is the liquid surrounding the baby in the womb.
Blood tests cannot be performed on unborn babies. Therefore, genetic testing is required for prenatal screenings. Newborn Screening
It is extremely important to diagnose a child who has SCD early on to better prevent complications associated with the disease. Every baby within the 50 states in the U.S. and the District of Columbia is required to be tested for SCD as a part of the newborn screening program. This testing involves pricking the baby’s heel to collect blood “spots” on a special paper. The blood sample is sent to a lab equipped to perform Hb isoelectric focusing and HPLC fractionation specifically intended to identify the types of hemoglobin present. The results are sent to the doctor who ordered the test, as well as the child’s primary doctor. If the baby is diagnosed with SCD, health providers from a special follow-up newborn screening group contact the family to inform the parents of the results.
Although SCD is present at birth, a newborn with the disease may not show any signs or symptoms for at least four months. Symptoms, and the time they take to present vary from person to person. Some of the more common symptoms of SCD include: Acute Pain People with SCD experience sever episodes of pain, known as sickle cell crises, which can occur without warning, often last for several days, and required hospitalization. The pain is a result of the blockage caused by abnormal blood cells in blood vessels, thereby hindering the delivery of oxygen to cells.
Since blood flows throughout the body, this pain can occur anywhere. However, the parts of the body most commonly affected are: Lower back Legs Arms Chest Abdomen Infections Sickle cells can cause damage to the spleen, which is the organ responsible for protection against bacteria. Damage to this organ causes a person to be more susceptible to infections, ranging from mild, such as the common cold, to potentially life-threatening, such as meningitis.
Frequent infections may be prevented if a doctor administers the appropriate vaccinations and antibiotics. Anemia Anemia in patients with SCD is attributed to a lower than normal red blood cell count, which results in an insufficient supply of oxygen. This symptom varies in severity, and causes a person feel tired and weak, with fatigue being one of the most common symptoms associates with anemia. Severe or long-lasting anemia may cause other complications in sickle cell patients, including damage to the heart, lungs, brain, kidney, spleen, and other organs of the body. In extreme cases, anemia may lead to death.
Other Complications There are a large range of other complications associated with SCD, varying from person to person. These include: Acute chest syndrome Stroke Brain complications Eye problems Heart disease Pulmonary Hypertension (high blood pressure in the lungs) Kidney problems Priapism (long-lasting erections in male patients, which may lead to impotence) Gallstones Liver Complications Leg Ulcers Jaundice (yellowing of the eyes and skin) Joint Complications Delayed growth and puberty Pregnancy complications Mental Health
Newborns who have been diagnosed with SCD needs to be referred to a medical provider who specializes in the disease to monitor their symptoms and begin treatment at the first sign. In these cases, the baby needs to have their first SCD doctor’s visit sooner than 8 weeks old. Those who have not been tested/diagnosed at birth need to visit a specialist as soon as the diagnosis is made. Sickle Cell treatment plans are intended to prevent or relieve pain, prevent organ damage, infections, and strokes, treat anemia, and control complications. SCD patients and their loved-ones are urged to develop a treatment plan to effectively manage these effects of the disease.
Pain Prevention and Treatment Those who suffer from more severe forms of sickle cell anemia may benefit from a daily dose of hydroxyurea. This medicine helps to reduce the number of crises, but not to treat them once they occur. Pain-related treatment options for sickle cell patients may vary depending on the severity of the pain they experience at any given time. At home treatments of mild pain include over-the-counter pain medicine and heating pads. In the event of a crisis, severe pain, hospitalization is always required. Treatment includes the administration of fluids and pain-controlling medicines.
Infection Prevention With SCD, it is critical to prevent infections where possible, as soon as possible, as these infections could lead to further, detrimental complications. The most effective way of preventing infections among people with SCD is to administer all vaccinations, one-time or routine, as soon as possible. These may begin as early as 8 weeks old with daily doses of penicillin, which continues until the child is about 5 years old. Children and adults should always be examined when they experience fevers, as early detection of any issues allows more effective treatment.
Blood Transfusions Blood transfusions are often used to treat progressively worsening anemia or complications. Most sickle cell patients receive at least occasional blood transfusions in their lifetime. The frequency with which blood transfusions are administered depend on the severity of the complications. Hematopoietic Stem Cell Transplantation As of now, hematopoietic stem cell transplantation is the only known cure for SCD. The procedure involves replacing the sickle cell patient’s damaged bone marrow