Thalassemia
Thalassemia is not a single disorder, but a group of inherited diseases of the blood with similar clinical effects. About 100,000 babies worldwide are born with severe forms of the disease each year.
The word “thalassemia” comes from the Greek words “thalasa” meaning "sea" and “emia” meaning "blood." The gene for thalassemia originated in the areas surrounding the Mediterranean Sea. Today the gene for thalassemia is most commonly found in populations around the Mediterranean Sea, Middle East, Africa and Asia.
Thalassemia affects the ability of the body to make hemoglobin, causing the anemia. Hemoglobin is the part of the red blood cell that carries oxygen from the lungs throughout the body to allow the body to function properly. Normal hemoglobin is made up of two proteins, alpha and beta.
What Are the Types of Thalassemia?
There are two main types of thalassemia, beta thalassemia and alpha thalassemia.
Beta Thalassemia
Beta thalassemia (also known as beta thalassemia minor) is an inherited form of thalassemia causing mild anemia.
- People with this condition have inherited one abnormal beta gene from one parent. The other beta gene is normal.
- This is not a disease and causes few, if any, symptoms. It is often confused with iron deficiency anemia, but treating with iron will not help.
Beta thalassemia intermedia is an inherited form of thalassemia causing mild to severe anemia.
- People with this condition have inherited two altered beta genes, one from each parent. These altered genes produce little or no normal hemoglobin.
- This disease can cause significant health problems including bone deformities, poor growth and an enlargement of the spleen.
- People with thalassemia intermedia may need blood transfusions intermittently to improve their quality of life.
Beta thalassemia major (also known as Cooley anemia) is an inherited form of thalassemia causing severe anemia.
- People with this condition have inherited two abnormal beta genes, one from each parent. The abnormal genes are unable to produce normal hemoglobin.
- This is the most severe type of thalassemia and usually requires frequent blood transfusions and medical care to survive.
- Without treatment with blood transfusions and careful medical monitoring the spleen, liver and heart become enlarged, bones become deformed and there is very poor growth.
- Frequent blood transfusions cause iron overload. Iron is deposited in the body’s organs and a drug treatment, called chelation, is given to remove the excess iron.
Alpha Thalassemia
The alpha thalassemias are caused by deletions or changes in one or more of the alpha globin genes. The alpha globin protein is produced by four genes instead of the usual two. Deletions may be on the same chromosome or there may one deletion on each chromosome.
- The silent carrier is an inherited form of alpha thalassemia where one of the four alpha globin genes is abnormal or deleted. It causes no symptoms and can only be confirmed with genetic studies.
- Hemoglobin constant spring is an inherited form of alpha thalassemia where one of the four alpha globin genes is mutated. It is an unusual form of the silent carrier that causes no symptoms.
- Alpha thalassemia trait (also known as mild alpha thalassemia) is an inherited form of alpha thalassemia causing mild anemia. People with this condition have inherited two deletions or changes in their alpha globin genes. This is not a disease and causes few, if any, symptoms. It is often confused with iron deficiency anemia, but treating with iron will not help.
- Hemoglobin H disease is an inherited form of alpha thalassemia causing a moderate anemia. People with this condition have inherited three deletions or changes in their alpha globin genes. This disease can cause health problems including fatigue, an enlarged spleen, bone deformities and worsening anemia when ill.
- Hemoglobin H constant spring is a more serious inherited form of alpha thalassemia causing severe anemia. People with this condition have inherited hemoglobin constant spring from one parent and alpha thalassemia trait from the other parent. People with this condition have significant health problems including severe fatigue, an enlarged spleen, bone deformities and frequent viral infections. Most people with this disease have an improved quality of life with frequent blood transfusions and close medical monitoring.
- Alpha thalassemia major (also known as hydrops fetalis) is an inherited form of alpha thalassemia where all four of the alpha globin genes are deleted. Babies with this condition usually die before or shortly after birth. If the condition is discovered before birth, it is possible to give blood transfusions in utero which allow the baby to be born. This child will require lifelong blood transfusions and medical care.
Other Types of Thalassemia
When the gene for alpha or beta thalassemia combines with another abnormal hemoglobin, there are other types of thalassemia a person can inherit.
- E beta thalassemia is an inherited form of thalassemia where a child inherits hemoglobin E from one parent and the abnormal beta gene from the other parent. This disease can produce symptoms like beta thalassemia intermedia (see above) or like beta thalassemia major (see above).
- Sickle beta thalassemia is an inherited form of sickle cell disease where a child inherits the gene for sickle cell from one parent and the abnormal beta gene from the other parent. Find more information here about sickle cell disease.
What Causes Thalassemia?
Thalassemia is a group of inherited diseases and inheritance can be complex. It is best to consult with a physician or genetic counselor in order to determine the risk for future children to have thalassemia trait or disease.
- Beta thalassemia trait — There is a 50 percent chance that a person with beta thalassemia trait will pass this gene on to any children they have.
- Beta thalassemia intermedia — A person with beta thalassemia intermedia will pass on an altered beta gene to any children they have and needs to be aware of any abnormal hemoglobin their partner may carry that could also be passed on to their children.
- Beta thalassemia major — A person with thalassemia major will pass on an abnormal beta gene to any children they may have and needs to be aware of any abnormal hemoglobin their partner may carry that could also be passed on to their children.
- Silent carrier — A person who is a silent carrier has a 50 percent chance of passing on this gene change to any children they may have.
- Hemoglobin constant spring — A person with hemoglobin constant spring has a 50 percent chance of passing on this gene change to any children they may have and needs to be aware of any abnormal hemoglobin their partner may carry that could also be passed on to their children.
- Alpha thalassemia trait — A person with alpha thalassemia trait has a 50 percent chance of passing on one or both deletions to any children they may have and needs to be aware of any abnormal hemoglobin their partner may carry that could also be passed on to their children.
- Hemoglobin H–A person with hemoglobin H disease will pass on one or two alpha globin gene deletions to any children they may have and needs to be aware of any abnormal hemoglobin their partner may carry that could also be passed on to their children.
- Hemoglobin H constant spring — A person with hemoglobin H constant spring will either pass on hemoglobin constant spring or alpha thalassemia trait to any children they may have and needs to be aware of any abnormal hemoglobin their partner may carry that could also be passed on to their children.
- E beta thalassemia — A person with E beta thalassemia will pass on either the hemoglobin E or the abnormal beta gene to any children they may have and needs to be aware of any abnormal hemoglobin their partner may carry that could also be passed on to their children.
How Is Thalassemia Diagnosed?
A blood sample is taken from the child to determine:
- Complete blood count (CBC): A CBC measures the size, number and maturity of different blood cells. It measures how anemic a person is.
- Hemoglobin Electrophoresis with A2 and F quantitation: This test determines the types of hemoglobin and quantifies the amounts of each of those hemoglobins.
- Genetic testing (DNA testing): Genetic testing determines the specific genetic changes in the alpha or beta globin genes which caused the thalassemia. It may be done to help clarify a diagnosis.
- Parent testing: A blood sample may be taken on the parents as well for some or all of the above studies.
What Are the Symptoms of Thalassemia?
Most children appear healthy at birth, but during the first year or two of life develop moderate to severe anemia. They grow slowly and often develop jaundice.
How Is Thalassemia Treated?
Most children with thalassemia require a life-long regimen of blood transfusions. Complications from the disease and its treatment include heart problems, liver damage, diabetes, infertility, growth failure and thin or deformed bones.