Alternative Names
HbS disease ; Hemoglobin S Disease; SCD; Sickle cell disorders; SS disease; sickle cell disease; Sickling disorder due to hemoglobin S; hemoglobinopathy; betaglobinopathy
Symptoms & Characteristics
Sickle cell anemia (also called sickle cell disease or Hemoglobin SS disease) is a genetic condition that affects hemoglobin, the molecule in red blood cells that transports oxygen throughout the body. Affected people have a variation in hemoglobin called hemoglobin S, which can distort red blood cells into a sickle (or crescent) shape. These "sickled" cells do not last as long as normal, round red blood cells, which leads to anemia. In addition, the cells can also block blood flow by getting stuck in blood vessels, which may lead to pain and organ damage. Other symptoms may include: fatigue, delayed growth and development, yellowing of the eyes and skin (jaundice), and high blood pressure in the blood vessels that supply the lungs (pulmonary hypertension).
Treatment
There is currently no cure for sickle cell anemia. However, early diagnosis, routine surveillance and treatment can help to manage some of the symptoms and sometimes prevent related problems. Regular treatment may be needed and may include blood transfusions.
How Common Is It?
Sickle cell anemia is the most common inherited blood condition in the United States, affecting approximately 75,000 Americans.
- Sickle cell anemia is most common in people of African, Greek, Turkish, Italian, Middle Eastern, Indian, Caribbean and Hispanic descent.
Genetics & Inheritance
Sickle cell disease is caused by a specific mutation in the HBB gene on the chromosome 11 at the location p15.5, which results in the production of hemoglobin S.
Over 200 mutations in the HBB gene have been found. Other specific mutations in the HBB gene cause different hemoglobin variants, like C, or a reduction in total beta-globin production, called beta-thalassemia. Having one sickle cell mutation, in addition to one other HBB mutation may cause varying degrees of sickle cell disease. For example, people with Hemoglobin SC disease tend to have milder symptoms than people with Hemoglobin SS disease.
We all have two copies of almost every gene – one from each parent. It is necessary to have two mutations, one from each parent, to be affected sickle cell anemia. This is called autosomal recessive inheritance.
- Both parents of an affected person are always both obligate carriers (each have only one mutation). Two carriers have a 25% chance with each pregnancy to have an affected child.
- Without a family history, the chance to be a carrier is determined by a person's ethnic background. For example, about 1 in 8 African-Americans is a carrier of sickle cell disease (also known as having AS trait or sickle cell trait).
There are many genetic and non-genetic conditions, which have symptoms that overlap with sickle cell anemia. A genetic consultation with a trained genetic professional is important for a complete evaluation, accurate diagnosis, as well as discussion of the benefits and limitations of testing and recurrence risk.
Genetic Testing
Clinical genetic testing for sickle cell anemia can be broken down into two categories: diagnostic testing and carrier testing.
- Diagnostic testing may be used to confirm or rule out a diagnosis in a person suspected to have sickle cell anemia.
- Carrier testing for sickle cell anemia is available for people of high risk ethnic groups.
Clinical genetic testing for sickle cell anemia is available online (over the internet) or through an in person genetic consultation. Go to the Tests tab to link to the best providers, compare providers and read provider reviews. Use our find a professional directory to locate a trained genetic professional in your area.
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