Sickle Cell AnemiaSickle cell anemia is a genetic disease of the red blood cells (RBCs). Normally RBCs are shaped like a disk. This gives them the flexibility ...
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Sickle cell anemia is a genetic disease of the red blood cells (RBCs). Normally RBCs are shaped like a disk. This gives them the flexibility to travel through even the smallest blood vessels. However, in people with sickle cell, the RBCs have an abnormal crescent shape. This makes them sticky and rigid. They can get trapped in small vessels and block blood from reaching different parts of the body. This can cause pain and tissue damage.
Sickle cell anemia is an autosomal recessive condition. You need two copies of the gene to have the disease. If you have only one copy of the gene, you are said to have sickle cell trait. Sickle cell trait explains the geographic distribution of sickle cell disease. It makes you more likely to survive a malaria infection. That’s why sickle cell is more common in areas that have, or had, a high prevalence of malaria.
Hemoglobin is the protein in RBCs that carries oxygen. It is made up of two alpha chains and two beta chains. These are made by the alpha and beta genes. The four main types of sickle cell anemia are caused by different mutations in these genes.
Hemoglobin SS Disease
Hemoglobin SS disease is the most common type of sickle cell disease. It occurs when you inherit copies of the hemoglobin S gene from both parents. This forms hemoglobin known as Hb SS.
Hemoglobin SC Disease
Hemoglobin SC disease is the second most common type of sickle cell disease. It occurs when you inherit the Hb C gene from one parent and the Hb S gene from the other. Individuals with Hb SC have similar symptoms to individuals with Hb SS. However, the anemia is less severe.
Hemoglobin SB+ (Beta) Thalassemia
Hemoglobin SB+ (Beta) thalassemia affects beta globin gene production. The size of the red blood cell is reduced because less beta protein is made. If inherited with the Hb S gene, you will have Hemoglobin S Beta thalassemia.
Beta-Zero thalassemia is the second type of beta thalassemia. It has similar symptoms to Hb SS anemia. However, sometimes the symptoms of beta-zero thalassemia are more severe. It is associated with a poorer prognosis.
People who only inherit a mutated gene from only one parent are said to have sickle cell trait. They may have no symptoms or reduced symptoms.
Children are only at risk for sickle cell if both parents carry sickle cell trait.
People from regions that have endemic malaria are more likely to be carriers. This includes people from Africa, India, the Mediterranean, and Saudi Arabia.
Symptoms of sickle cell anemia usually show up at a young age. They may appear in babies as early as 4 months old.
Anemia is a shortage of RBCs. Sickle cells are easily broken. This breaking apart of RBCs is called chronic hemolysis. RBCs generally live for about 120 days. Sickle cells live for a maximum of 10 to 20 days.
Hand-Foot Syndrome occurs when sickle-shaped RBCs block blood vessels in the hands or feet. This causes the hands and feet to swell. It can also cause leg ulcers. Swollen hands and feet are often the first sign of sickle cell anemia in babies.
Splenic sequestration is a blockage of the splenic vessels by sickle cells. It causes acute, painful enlargement of the spleen.
Delayed growth often occurs in people with sickle cell anemia. Children are generally shorter but regain their height by adulthood. Sexual maturation may also be delayed. This happens because sickle cell RBCs can’t supply enough oxygen and nutrients.
Sickle cell anemia can cause severe complications. These complications appear when the sickle cells block vessels in different areas of the body. Painful or damaging blockages are called sickle cell crises.
Neurological complications include fits, bleeding in the brain, or even coma. They are caused by brain blockages. Immediate treatment should be sought.
Blindness is caused by blockages in the vessels supplying the eyes. This can damage the retina.
Skin ulcers in the legs can occur if small vessels there are blocked.
Priapism is a lingering, painful erection that can be seen in some men with sickle cell. This happens when the blood vessels in the penis are blocked. If untreated, it can lead to impotence. Priapism can be treated using ?-adrenergic blocking drugs, analgesia, and hydration.
Gallstones are one complication not caused by a vessel blockage. Instead, they are caused by the break down of RBCs. A byproduct of this breakdown is bilirubin. High levels of bilirubin can lead to gallstones. These are also called pigment stones.
If you are worried about your newborn baby, genetic testing can screen for the condition before or after birth. Pre-birth testing looks for the sickle cell gene in your amniotic fluid.
In children and adults, one or more of the following procedures may also be used to diagnose sickle cell.
Detailed Patient History
This condition often first appears as acute pain in the hands and feet. Patients may also have:
- severe pain in the bones
- painful enlargement of the spleen
- growth problems
- respiratory infections
- ulcers of the legs
- heart problems
If you have any of these symptoms, your doctor may want to test you for sickle cell anemia.
Several blood tests can be used to look for sickle cell anemia:
- blood counts can reveal an abnormal Hb level in the range of 6 – 8 g/dL
- blood films may show RBCs that appear as irregularly contracted cells
- sickle solubility tests look for the presence of Hb S
Hb electrophoresis is always needed to confirm the diagnosis of sickle cell. It measures the different types of hemoglobin in the blood.
A number of different treatments are available for sickle cell anemia.
Antibiotics like penicillin may be given from 2 months of age to 5 years. They help prevent pneumonia in sickle cell patients.
Pain medication is used to relieve the pain during a sickle crisis. You may need over-the-counter drugs or strong prescription pain medication like morphine.
Hydroxyurea (Droxia, Hydrea) helps to increase production of fetal hemoglobin. It may reduce the number of blood transfusions.
Immunizations can help prevent infections. Patients tend to have lower immunity.
Surgery may be used to treat persistent painful erections.
Bone marrow transplant has been used to treat sickle cell anemia. Children younger than 16 years of age who have severe complications and have a matching donor are the best candidates.
Blood transfusions can also treat sickle cell anemia. Packed red cells are removed from donated blood and given to patients. This improves transport of oxygen and nutrients.
Supplemental oxygen is given through a mask. It makes breathing easier and improves oxygen levels in the blood.
There are things you can do at home to help your sickle cell symptoms.
Heating pads and relaxation may help you deal with pain.
Daily supplementation of folic acid and a healthy diet can help you make new RBCs. Fruits, vegetables, and whole-wheat grains are important.
Increased water drinking can reduce chances of a sickle cell crisis.
Avoiding extreme temperatures can also reduce the chance of a crisis. Exercising regularly and reducing stress may help as well.
Support groups can help you deal with this condition. Learn all you can about the disease.
The prognosis of the disease varies. Some patients have frequent and painful sickle cell crises. Others only rarely have attacks.
Recent treatment advances have prolonged and improved the quality of life for sickle cell patients. According to statistics published by the University of Maryland Medical Center, the average life span for people with sickle cell anemia has risen from 14 years to 50 years since 1973. Women have a higher average life span than men.
Sickle cell anemia is an inherited disease. If you are worried that you might be a carrier, talk to a genetic counselor. This can help you understand possible treatments, preventive measures, and reproductive options.
Edited by: Eric Searleman
Medically Reviewed by: George Krucik, MD
Published: Jul 25, 2012
Last Updated: Nov 22, 2013
Published By: Healthline Networks, Inc.
- López, C et al. (2010, November 1) Mechanisms of genetically-based resistance to malaria. Gene. 467(1-2):1-12
- Sickle Cell Anemia. (n.d) Mayo Clinic. Retrieved February 23, 2012, from http://www.mayoclinic.com/health/sickle-cell-anemia/DS00324
- Sickle Cell Anemia. (n.d) University of Maryland Medical Center. Retrieved February 23, 2012 from http://www.umm.edu/ency/article/000527.htm