Sickle cell disease is caused by a mutation in the beta globin gene, resulting in an abnormal hemoglobin called sickle hemoglobin, or Hb S. Different types of sickle cell disease arise based on whether the hemoglobin beta S gene is inherited with another beta S gene or with a different beta gene mutation.
Hemoglobin SS disease is the most common and most severe type of sickle cell disease. It occurs when you inherit the hemoglobin S gene mutation from both parents. In this type, the body only produces hemoglobin S. Hemoglobin S beta zero thalassemia occurs when you inherit the hemoglobin beta S gene from one parent and a hemoglobin beta0 thalassemia gene mutation from the other parent. Sickle Hemoglobin-D Disease : Through research, hemoglobin D, which is a different substitution of the beta globin gene, has been found to interact with the sickle hemoglobin gene.
Individuals with Sickle Hemoglobin-D disease SD have moderately severe anemia and occasional pain episodes. Sickle Hemoglobin-O Disease : Hemoglobin O, another type of substitution in the beta globin gene, also interacts with sickle hemoglobin. 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. Symptoms are not as severe. Sickle beta-zero thalassemia is the fourth type of sickle cell disease.
It also involves the beta globin gene. 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 hemoglobin S from 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 disease if both parents carry sickle cell trait. A blood test called a hemoglobin electrophoresis can also determine which type you might carry.
People from regions that have endemic malaria are more likely to be carriers. This includes people from:. SCD can cause severe complications, which appear when the sickle cells block vessels in different areas of the body. Painful or damaging blockages are called sickle cell crises. They can be caused by a variety of circumstances, including:. 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 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 a sudden, painful enlargement of the spleen. The spleen may have to be removed due to complications of sickle cell disease in an operation known as a splenectomy.
Some sickle cell patients will sustain enough damage to their spleen that it becomes shrunken and ceases to function at all. This is called autosplenectomy. Patients without a spleen are at higher risk for infections from bacteria such as Streptococcus , Haemophilus , and Salmonella species. Delayed growth often occurs in people with SCD.
Children are generally shorter but regain their height by adulthood. Sexual maturation may also be delayed. Seizures, strokes, or even coma can result from sickle cell disease. They are caused by brain blockages. Immediate treatment should be sought. Since SCD interferes with blood oxygen supply, it can also cause heart problems which can lead to heart attacks , heart failure , and abnormal heart rhythms.
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