What Is Thalassaemia?
Thalassaemia is an inherited blood disorder that causes mild or severe anaemia (uh-NEE-me-uh). The anaemia is due to reduced haemoglobin (HEE-muh-glow-bin) and fewer red blood cells than normal. Haemoglobin is the protein in red blood cells that carries oxygen to all parts of the body.
In people with thalassaemia, the genes that code for haemoglobin are missing or variant (different than the normal genes). Severe forms of thalassaemia are usually diagnosed in early childhood and are lifelong conditions.
The two main types of thalassaemia, alpha and beta, are named for the two protein chains that make up normal haemoglobin. The genes for each type of thalassaemia are passed from parents to their children. Alpha and beta thalassaemias have both mild and severe forms.
Alpha thalassaemia occurs when one or more of the four genes needed for making the alpha globin chain of haemoglobin are variant or missing. Moderate to severe anaemia results when more than two genes are affected. The most severe form of alpha thalassaemia is known as alpha thalassaemia major. It can result in miscarriage.
Beta thalassaemia occurs when one or both of the two genes needed for making the beta globin chain of haemoglobin are variant. The severity of illness depends on whether one or both genes are affected and the nature of the abnormality. If both genes are affected, anaemia can range from moderate to severe. The severe form of beta thalassaemia is also known as Cooley’s anaemia. Cooley’s anaemia is the most common severe form of thalassaemia in the United States.
Other Names for Thalassaemia
- Alpha thalassaemia “silent carrier”
- Mild alpha thalassaemia, also called alpha thalassaemia minor or alpha thalassaemia trait
- Haemoglobin H disease
- Hydrops foetalis, or alpha thalassaemia major
- Beta thalassaemia minor, also called thalassaemia minor or thalassaemia trait
- Beta thalassaemia intermedia, also called thalassaemia intermedia or mild Cooley’s anaemia
- Beta thalassaemia major, also called thalassaemia major or Cooley’s anaemia
- Mediterranean anaemia
Cooley’s anaemia is another name for the severe form of beta thalassaemia. The name is sometimes used to refer to any type of thalassaemia that requires treatment with regular blood transfusions.
What Causes Thalassaemia?
Thalassaemia is caused by variant or missing genes that affect how the body makes haemoglobin. Haemoglobin is the protein in red blood cells that carries oxygen. People with thalassaemia make less haemoglobin and fewer circulating red blood cells than normal. The result is mild or severe anaemia.
Many possible combinations of variant genes cause the various types of thalassaemia. Thalassaemia is always inherited (passed from parents to children). People with moderate to severe forms of thalassaemia received variant genes from both parents. A person who inherits a thalassaemia gene or genes from one parent and normal genes from the other parent is a carrier (thalassaemia trait). Carriers often have no signs of illness other than mild anaemia, but they can pass the variant genes on to their children.
Haemoglobin includes two kinds of protein chains called alpha globin chains and beta globin chains. If the problem is with the alpha globin part of haemoglobin, the disorder is alpha thalassaemia. If the problem is with the beta globin part, it is called beta thalassaemia. There are both mild and severe forms of alpha and beta thalassaemia. Severe beta thalassaemia is often called Cooley’s anaemia.
Four genes are involved in making the alpha globin part of haemoglobin—two from each parent. Alpha thalassaemia occurs when one or more of these genes is variant or missing.
- People with only one gene affected are called silent carriers and have no sign of illness.
- People with two genes affected (called alpha thalassaemia trait, or alpha thalassaemia minor) have mild anaemia and are considered carriers.
- People with three genes affected have moderate to severe anaemia, or haemoglobin H disease.
- Babies with all four genes affected (a condition called alpha thalassaemia major, or hydrops foetalis) usually die before or shortly after birth.
If two people with alpha thalassaemia trait (carriers) have a child, the baby could have a mild or severe form of alpha thalassaemia or could be healthy.
Two genes are involved in making the beta globin part of haemoglobin—one from each parent. Beta thalassaemia occurs when one or both of the two genes are variant.
- If one gene is affected, a person is a carrier and has mild anaemia. This condition is called beta thalassaemia trait, or beta thalassaemia minor.
- If both genes are variant, a person may have moderate anaemia (beta thalassaemia intermedia, or mild Cooley’s anaemia) or severe anaemia (beta thalassaemia major, or Cooley’s anaemia).
- Cooley’s anaemia, or beta thalassaemia major, is a rare condition. A survey in 1993 found 518 Cooley’s anaemia patients in the United States. Most of these persons had the severe form of the illness, but there may be more who are not diagnosed.
If two people with beta thalassaemia trait (carriers) have a baby, one of three things can happen:
- The baby could receive two normal genes (one from each parent) and have normal blood (1 in 4 chance, or 25 percent).
- The baby could receive one normal gene from one parent and one variant gene from the other parent and have thalassaemia trait (2 in 4 chance, or 50 percent).
- The baby could receive two thalassaemia genes (one from each parent) and have a moderate to severe form of the disease (1 in 4 chance, or 25 percent).
Who Is At Risk for Thalassaemia?
- Thalassaemia is passed from parents to children through their genes.
- Thalassaemia affects both males and females.
- Beta thalassaemias affect people of Mediterranean origin or ancestry (Greek, Italian, Middle Eastern) and people of Asian and African descent.
- Alpha thalassaemias mostly affect people of Southeast Asian, Indian, Chinese, or Filipino origin or ancestry.
What Are the Signs and Symptoms of Thalassaemia?
The symptoms of thalassaemia depend on the type and severity of the disease. Symptoms occur when not enough oxygen gets to various parts of the body due to low haemoglobin and a shortage of red blood cells in the blood (anaemia).
“Silent carriers” and persons with alpha thalassaemia trait or beta thalassaemia trait (also called carriers) usually have no symptoms. Those with alpha or beta thalassaemia trait often have mild anaemia that may be found by a blood test.
In more severe types of thalassaemia, such as Cooley’s anaemia, signs of the severe anaemia are seen in early childhood and may include:
- Fatigue (feeling tired) and weakness
- Pale skin or jaundice (yellowing of the skin)
- Protruding abdomen, with enlarged spleen and liver
- Dark urine
- Abnormal facial bones and poor growth
Babies with all four genes affected (a condition called alpha thalassaemia major, or hydrops foetalis) usually die before or shortly after birth.
How Is Thalassaemia Diagnosed?
Thalassaemia is diagnosed using blood tests, including a complete blood count (CBC) and special haemoglobin studies.
- A CBC provides information about the amount of haemoglobin and the different kinds of blood cells, such as red blood cells, in a sample of blood. People with thalassaemia have fewer red blood cells than normal and less haemoglobin than normal in their blood. Carriers of the trait may have slightly small red blood cells as their only sign.
- Haemoglobin studies measure the types of haemoglobin in a blood sample.
Cooley’s anaemia is usually diagnosed in early childhood because of signs and symptoms, including severe anaemia. Some people with milder forms of thalassaemia may be diagnosed after a routine blood test shows that they have anaemia. Doctors suspect thalassaemia if a child has anaemia and is a member of an ethnic group that is at risk for thalassaemia.
To distinguish anaemia caused by iron deficiency from anaemia caused by thalassaemia, tests of the amount of iron in the blood may be done. Iron-deficiency anaemia occurs because the body doesn’t have enough iron for making haemoglobin. The anaemia in thalassaemia occurs not because of a lack of iron, but because of a problem with either the alpha globin chain or the beta globin chain of haemoglobin. Iron supplements do nothing to improve the anaemia of thalassaemia, because missing iron is not the problem.
Family genetic studies are also helpful in diagnosing thalassaemia. This involves taking a family history and doing blood tests on family members.
Prenatal testing can determine if an unborn baby has thalassaemia and how severe it is likely to be.
How Is Thalassaemia Treated?
Treatment for thalassaemia depends on the type and severity of the disease.
- People who are carriers (they have thalassaemia trait) usually have no symptoms and need no treatment.
- Those with moderate forms of thalassaemia (for example, thalassaemia intermedia) may need blood transfusions occasionally, such as when they are experiencing stress due to an infection. If a person with thalassaemia intermedia worsens and needs regular transfusions, he or she is no longer considered to have thalassaemia intermedia; instead, the person is said to have thalassaemia major, or Cooley’s anaemia.
- Those with severe thalassaemia have a serious and life-threatening illness. They are treated with regular blood transfusions, iron chelation (ke-LAY-shun) therapy, and bone marrow transplants. Without treatment, children with severe thalassaemia do not live beyond early childhood. People with severe thalassaemia who are able to continue therapy successfully may live into their thirties, forties, and beyond.
Severe forms of thalassaemia are treated by regular blood transfusions. A blood transfusion, given through a needle in a vein, provides blood containing normal red blood cells from healthy donors. In thalassaemia treatment, blood transfusions are done on a schedule (often every 2–4 weeks) to keep haemoglobin levels and red blood cell numbers at normal levels. Transfusion therapy can allow a person with severe thalassaemia to feel better, enjoy normal activities, and live longer.
Transfusion therapy, while lifesaving, is expensive and carries a risk of transmitting viral and bacterial diseases (for example, hepatitis). Transfusion also leads to excess iron in the blood (iron overload), which can damage the liver, heart, and other parts of the body. To prevent damage, iron chelation therapy is needed to remove excess iron from the body.
Iron Chelation Therapy
Iron chelation therapy uses medicine to remove the excess iron that builds up in the body when a person has frequent blood transfusions. If the iron is not removed, it damages body organs, such as the heart and liver.
The medicine, deferoxamine (deh-fer-ROX-uh-meen), works best when given slowly under the skin, usually with a small portable pump overnight. This therapy is demanding and sometimes is mildly painful, so some people stop chelation therapy. A pill form of iron chelation therapy, deferasirox, was approved in November 2005 for use in the United States.
People who have iron overload should not take vitamins or other supplements that contain iron.
Surgery may be needed if body organs, such as the spleen or gall bladder, are affected. For example, if the spleen becomes inflamed and enlarged, it may be removed. If gallstones develop, the gall bladder may be removed.
Bone Marrow or Stem Cell Transplants
Bone marrow or stem cell transplants have been used successfully in some children with severe thalassaemia. This is a risky procedure, but it offers a cure for those children who qualify.
People with severe thalassaemia are more likely to get infections that can worsen their anaemia. They should get an annual flu shot and the pneumonia vaccine to help prevent infections.
Folic acid is a B vitamin that helps build red blood cells. People with thalassaemia should take folic acid supplements.
Researchers are also studying other treatments, such as gene therapy and foetal haemoglobin.
Someday, it may be possible to cure thalassaemia in an unborn child by inserting a normal gene into the child’s stem cells.
Researchers are studying ways to enhance production of foetal haemoglobin in people with thalassaemia. Foetal haemoglobin is the type of haemoglobin made by the body before birth. After birth, the body usually switches from making foetal haemoglobin to the adult form of haemoglobin. Some children have a gene variant that prevents the switch, and their continuing production of foetal haemoglobin lessens the severity of their illness. Researchers are testing ways to enhance foetal haemoglobin production after birth.
How Can Thalassaemia Be Prevented?
Although thalassaemia cannot be prevented, it can be identified before birth by prenatal diagnosis.
People who have or believe that they may carry the thalassaemia genes can receive genetic counselling to avoid passing the disorder to their children.
Living With Thalassaemia
The Cooley’s Anaemia Foundation offers support to people with various types of thalassaemia through its Thalassaemia Action Group.
If you have moderate or severe thalassaemia, you need to take care of your overall health.
- Follow your treatment plan. See your doctor regularly for checkups and treatment.
- If you must have regular blood transfusions and iron chelation therapy, it is important to continue with treatment as recommended.
- If you have regular blood transfusions, you should avoid taking vitamins or other supplements containing iron.
- Maintain a healthy diet. Your doctor may also give you a supplement of folic acid (a B vitamin) every day to help your body make new red blood cells.
- Get a flu shot every year and the pneumococcal vaccine to prevent infections.
- Thalassaemia is an inherited blood disorder that can cause mild to severe anaemia.
- Thalassaemia involves problems with the production of haemoglobin in red blood cells. As a result, a person with thalassaemia doesn’t have enough haemoglobin or red blood cells to carry oxygen throughout the body (anaemia).
- Two main types of thalassaemia are alpha and beta thalassaemia. Alpha thalassaemia occurs when there is a problem with the alpha globin chain that is part of haemoglobin. Beta thalassaemia occurs when there is a problem with the beta globin chain.
- Mild, moderate, and severe forms of thalassaemia occur. Severe beta thalassaemia is often called Cooley’s anaemia.
- The most common severe form of thalassaemia seen in the United States is beta thalassaemia major, or Cooley’s anaemia. It mainly affects people from Mediterranean countries and Asia.
- Some people are “silent carriers” with no symptoms. Other carriers have mild anaemia but usually need no treatment. Carriers can pass thalassaemia genes on to their children.
- Severe thalassaemia is treated with frequent blood transfusions and iron chelation therapy to remove excess iron that builds up in the body from the transfusions.
- Bone marrow or stem cell transplants have cured thalassaemia in some children, but this treatment is not available for most people with thalassaemia.
- Researchers are studying new treatments, including ways to cure thalassaemia through stem cell and gene therapies.