For more information, visit http://www.nhlbi.nih.gov/health/health-topics/topics/thalassemia/

What Are Thalassemias?

Thalassemias (thal-a-SE-me-ahs) are inherited blood disorders. "Inherited" means that the disorder is passed from parents to children through genes.

Thalassemias cause the body to make fewer healthy red blood cells and less hemoglobin (HEE-muh-glow-bin) than normal. Hemoglobin is an iron-rich protein in red blood cells. It carries oxygen to all parts of the body. Hemoglobin also carries carbon dioxide (a waste gas) from the body to the lungs, where it's exhaled.

People who have thalassemias can have mild or severe anemia (uh-NEE-me-uh). Anemia is caused by a lower than normal number of red blood cells or not enough hemoglobin in the red blood cells.

Overview

Normal hemoglobin, also called hemoglobin A, has four protein chains—two alpha globin and two beta globin. The two major types of thalassemia, alpha and beta, are named after defects in these protein chains.

Four genes (two from each parent) are needed to make enough alpha globin protein chains. Alpha thalassemia trait occurs if one or two of the four genes are missing. If more than two genes are missing, moderate to severe anemia occurs.

The most severe form of alpha thalassemia is called alpha thalassemia major or hydrops fetalis. Babies who have this disorder usually die before or shortly after birth.

Two genes (one from each parent) are needed to make enough beta globin protein chains. Beta thalassemia occurs if one or both genes are altered.

The severity of beta thalassemia depends on how much one or both genes are affected. If both genes are affected, the result is moderate to severe anemia. The severe form of beta thalassemia is known as thalassemia major or Cooley's anemia.

Thalassemias affect males and females. The disorders occur most often among people of Italian, Greek, Middle Eastern, Southern Asian, and African descent. Severe forms usually are diagnosed in early childhood and are lifelong conditions.

Doctors diagnose thalassemias using blood tests. The disorders are treated with blood transfusions, medicines, and other procedures.

Outlook

Treatments for thalassemias have improved over the years. People who have moderate or severe thalassemias are now living longer and have better quality of life.

However, complications from thalassemias and their treatments are frequent. People who have moderate or severe thalassemias must closely follow their treatment plans. They need to take care of themselves to remain as healthy as possible.

Other Names for Thalassemias

The various types of thalassemia have specific names related to the severity of the disorder. (For more information about the types of thalassemia, go to "What Causes Thalassemias?")

Alpha Thalassemias

Alpha thalassemia silent carrier
Alpha thalassemia minor, also called alpha thalassemia trait
Hemoglobin H disease
Alpha thalassemia major, also called hydrops fetalis

Beta Thalassemias

Beta thalassemia minor, also called beta thalassemia trait
Beta thalassemia intermedia
Beta thalassemia major, also called Cooley's anemia or beta-zero (ß⁰) thalassemia
Beta-plus (ß⁺) thalassemia
Mediterranean anemia

What Causes Thalassemias?

Your body makes three types of blood cells: red blood cells, white blood cells, and platelets (PLATE-lets). Red blood cells contain hemoglobin, an iron-rich protein that carries oxygen from your lungs to all parts of your body. Hemoglobin also carries carbon dioxide (a waste gas) from your body to your lungs, where it's exhaled.

Hemoglobin has two kinds of protein chains: alpha globin and beta globin. If your body doesn't make enough of these protein chains or they're abnormal, red blood cells won't form correctly or carry enough oxygen. Your body won't work well if your red blood cells don't make enough healthy hemoglobin.

Genes control how the body makes hemoglobin protein chains. When these genes are missing or altered, thalassemias occur.

Thalassemias are inherited disorders—that is, they're passed from parents to children through genes. People who inherit faulty hemoglobin genes from one parent but normal genes from the other are called carriers. Carriers often have no signs of illness other than mild anemia. However, they can pass the faulty genes on to their children.

People who have moderate to severe forms of thalassemia have inherited faulty genes from both parents.

Alpha Thalassemias

You need four genes (two from each parent) to make enough alpha globin protein chains. If one or more of the genes is missing, you'll have alpha thalassemia trait or disease. This means that your body doesn't make enough alpha globin protein.

If you're only missing one gene, you're a "silent" carrier. This means you won't have any signs of illness.
If you're missing two genes, you have alpha thalassemia trait (also called alpha thalassemia minor). You may have mild anemia.
If you're missing three genes, you likely have hemoglobin H disease (which a blood test can detect). This form of thalassemia causes moderate to severe anemia.

Very rarely, a baby is missing all four genes. This condition is called alpha thalassemia major or hydrops fetalis. Babies who have hydrops fetalis usually die before or shortly after birth.

Example of an Inheritance Pattern for Alpha Thalassemia

The picture shows one example of how alpha thalassemia is inherited. The alpha globin genes are located on chromosome 16. A child inherits four alpha globin genes (two from each parent). In this example, the father is missing two alpha globin genes and the mother is missing one alpha globin gene.

Each child has a 25 percent chance of inheriting two missing genes and two normal genes (thalassemia trait), three missing genes and one normal gene (hemoglobin H disease), four normal genes (no anemia), or one missing gene and three normal genes (silent carrier).

Beta Thalassemias

You need two genes (one from each parent) to make enough beta globin protein chains. If one or both of these genes are altered, you'll have beta thalassemia. This means that your body won’t make enough beta globin protein.

If you have one altered gene, you're a carrier. This condition is called beta thalassemia trait or beta thalassemia minor. It causes mild anemia.
If both genes are altered, you'll have beta thalassemia intermedia or beta thalassemia major (also called Cooley's anemia). The intermedia form of the disorder causes moderate anemia. The major form causes severe anemia.

Example of an Inheritance Pattern for Beta Thalassemia

The picture shows one example of how beta thalassemia is inherited. The beta globin gene is located on chromosome 11. A child inherits two beta globin genes (one from each parent). In this example, each parent has one altered beta globin gene.

Each child has a 25 percent chance of inheriting two normal genes (no anemia), a 50 percent chance of inheriting one altered gene and one normal gene (beta thalassemia trait), or a 25 percent chance of inheriting two altered genes (beta thalassemia major).

Who Is at Risk for Thalassemias?

Family history and ancestry are the two risk factors for thalassemias.

Family History

Thalassemias are inherited—that is, the genes for the disorders are passed from parents to their children. If your parents have missing or altered hemoglobin-making genes, you may have thalassemia.

Ancestry

Thalassemias occur most often among people of Italian, Greek, Middle Eastern, Southern Asian, and African descent.

What Are the Signs and Symptoms of Thalassemias?

A lack of oxygen in the bloodstream causes the signs and symptoms of thalassemias. The lack of oxygen occurs because the body doesn't make enough healthy red blood cells and hemoglobin. The severity of symptoms depends on the severity of the disorder.

No Symptoms

Alpha thalassemia silent carriers generally have no signs or symptoms of the disorder. The lack of alpha globin protein is so minor that the body's hemoglobin works normally.

Mild Anemia

People who have alpha or beta thalassemia trait can have mild anemia. However, many people who have these types of thalassemia have no signs or symptoms.

Mild anemia can make you feel tired. Mild anemia caused by alpha thalassemia trait might be mistaken for iron-deficiency anemia.

Mild to Moderate Anemia and Other Signs and Symptoms

People who have beta thalassemia intermedia have mild to moderate anemia. They also may have other health problems, such as:

Slowed growth and delayed puberty. Anemia can slow down a child's growth and development.
Bone problems. Thalassemia may cause bone marrow to expand. Bone marrow is the spongy substance inside bones that makes blood cells. When bone marrow expands, the bones become wider than normal. They may become brittle and break easily.
An enlarged spleen. The spleen is an organ that helps your body fight infection and remove unwanted material. When a person has thalassemia, the spleen has to work very hard. As a result, the spleen becomes larger than normal. This makes anemia worse. If the spleen becomes too large, it must be removed.

Severe Anemia and Other Signs and Symptoms

People who have hemoglobin H disease or beta thalassemia major (also called Cooley's anemia) have severe thalassemia. Signs and symptoms usually occur within the first 2 years of life. They may include severe anemia and other health problems, such as:

A pale and listless appearance
Poor appetite
Dark urine (a sign that red blood cells are breaking down)
Slowed growth and delayed puberty
Jaundice (a yellowish color of the skin or whites of the eyes)
An enlarged spleen, liver, or heart
Bone problems (especially with bones in the face)

Complications of Thalassemias

Better treatments now allow people who have moderate and severe thalassemias to live much longer. As a result, these people must cope with complications of these disorders that occur over time.

Heart and Liver Diseases

Regular blood transfusions are a standard treatment for thalassemias. Transfusions can cause iron to build up in the blood (iron overload). This can damage organs and tissues, especially the heart and liver.

Heart disease caused by iron overload is the main cause of death in people who have thalassemias. Heart disease includes heart failure, arrhythmias (irregular heartbeats), and heart attack.

Infection

Among people who have thalassemias, infections are a key cause of illness and the second most common cause of death. People who have had their spleens removed are at even higher risk because they no longer have this infection-fighting organ.

Osteoporosis

Many people who have thalassemias have bone problems, including osteoporosis (OS-te-o-po-RO-sis). This is a condition in which bones are weak and brittle and break easily.

How Are Thalassemias Diagnosed?

Doctors diagnose thalassemias using blood tests, including a complete blood count (CBC) and special hemoglobin tests.

A CBC measures the amount of hemoglobin and the different kinds of blood cells, such as red blood cells, in a sample of blood. People who have thalassemias have fewer healthy red blood cells and less hemoglobin than normal in their blood. People who have alpha or beta thalassemia trait may have red blood cells that are smaller than normal.
Hemoglobin tests measure the types of hemoglobin in a blood sample. People who have thalassemias have problems with the alpha or beta globin protein chains of hemoglobin.

Moderate and severe thalassemias usually are diagnosed in early childhood. This is because signs and symptoms, including severe anemia, often occur within the first 2 years of life.

People who have milder forms of thalassemia might be diagnosed after a routine blood test shows they have anemia. Doctors might suspect thalassemia if a person has anemia and is a member of an ethnic group that's at increased risk for thalassemias. (For more information, go to "Who Is at Risk for Thalassemias?")

Doctors also test the amount of iron in the blood to find out whether the anemia is due to iron deficiency or thalassemia. Iron-deficiency anemia occurs if the body doesn't have enough iron to make hemoglobin. The anemia in thalassemia occurs because of a problem with either the alpha globin or beta globin chains of hemoglobin, not because of a lack of iron.

Because thalassemias are passed from parents to children through genes, family genetic studies also can help diagnose the disorder. These studies involve taking a family medical history and doing blood tests on family members. The tests will show whether any family members have missing or altered hemoglobin genes.

If you know of family members who have thalassemias and you're thinking of having children, consider talking with your doctor and a genetic counselor. They can help determine your risk for passing the disorder to your children.

If you're expecting a baby and you and your partner are thalassemia carriers, you may want to consider prenatal testing.

Prenatal testing involves taking a sample of amniotic fluid or tissue from the placenta. (Amniotic fluid is the fluid in the sac surrounding a growing embryo. The placenta is the organ that attaches the umbilical cord to the mother's womb.) Tests done on the fluid or tissue can show whether your baby has thalassemia and how severe it might be.

How Are Thalassemias Treated?

Treatments for thalassemias depend on the type and severity of the disorder. People who are carriers or who have alpha or beta thalassemia trait have mild or no symptoms. They’ll likely need little or no treatment.

Doctors use three standard treatments for moderate and severe forms of thalassemia. These treatments include blood transfusions, iron chelation (ke-LAY-shun) therapy, and folic acid supplements. Other treatments have been developed or are being tested, but they're used much less often.

Standard Treatments

Blood Transfusions

Transfusions of red blood cells are the main treatment for people who have moderate or severe thalassemias. This treatment gives you healthy red blood cells with normal hemoglobin.

During a blood transfusion, a needle is used to insert an intravenous (IV) line into one of your blood vessels. Through this line, you receive healthy blood. The procedure usually takes 1 to 4 hours.

Red blood cells live only for about 120 days. So, you may need repeated transfusions to maintain a healthy supply of red blood cells.

If you have hemoglobin H disease or beta thalassemia intermedia, you may need blood transfusions on occasion. For example, you may have transfusions when you have an infection or other illness, or when your anemia is severe enough to cause tiredness.

If you have beta thalassemia major (Cooley's anemia), you’ll likely need regular blood transfusions (often every 2 to 4 weeks). These transfusions will help you maintain normal hemoglobin and red blood cell levels.

Blood transfusions allow you to feel better, enjoy normal activities, and live into adulthood. This treatment is lifesaving, but it's expensive and carries a risk of transmitting infections and viruses (for example, hepatitis). However, the risk is very low in the United States because of careful blood screening.

For more information, go to the Health Topics Blood Transfusion article.

Iron Chelation Therapy

The hemoglobin in red blood cells is an iron-rich protein. Thus, regular blood transfusions can lead to a buildup of iron in the blood. This condition is called iron overload. It damages the liver, heart, and other parts of the body.

To prevent this damage, doctors use iron chelation therapy to remove excess iron from the body. Two medicines are used for iron chelation therapy.

Deferoxamine is a liquid medicine that's given slowly under the skin, usually with a small portable pump used overnight. This therapy takes time and can be mildly painful. Side effects include problems with vision and hearing.
Deferasirox is a pill taken once daily. Side effects include headache, nausea (feeling sick to the stomach), vomiting, diarrhea, joint pain, and tiredness.

Folic Acid Supplements

Folic acid is a B vitamin that helps build healthy red blood cells. Your doctor may recommend folic acid supplements in addition to treatment with blood transfusions and/or iron chelation therapy.

Other Treatments

Other treatments for thalassemias have been developed or are being tested, but they're used much less often.

Blood and Marrow Stem Cell Transplant

A blood and marrow stem cell transplant replaces faulty stem cells with healthy ones from another person (a donor). Stem cells are the cells inside bone marrow that make red blood cells and other types of blood cells.

A stem cell transplant is the only treatment that can cure thalassemia. But only a small number of people who have severe thalassemias are able to find a good donor match and have the risky procedure.

For more information, go to the Health Topics Blood and Marrow Stem Cell Transplant article.

Possible Future Treatments

Researchers are working to find new treatments for thalassemias. For example, it might be possible someday to insert a normal hemoglobin gene into stem cells in bone marrow. This will allow people who have thalassemias to make their own healthy red blood cells and hemoglobin.

Researchers also are studying ways to trigger a person's ability to make fetal hemoglobin after birth. This type of hemoglobin is found in fetuses and newborns. After birth, the body switches to making adult hemoglobin. Making more fetal hemoglobin might make up for the lack of healthy adult hemoglobin.

Treating Complications

Better treatments now allow people who have moderate and severe thalassemias to live longer. As a result, these people must cope with complications that occur over time.

An important part of managing thalassemias is treating complications. Treatment might be needed for heart or liver diseases, infections, osteoporosis, and other health problems.

How Can Thalassemias Be Prevented?

You can’t prevent thalassemias because they’re inherited (passed from parents to children through genes). However, prenatal tests can detect these blood disorders before birth.

Family genetic studies may help find out whether people have missing or altered hemoglobin genes that cause thalassemias. (For more information, go to "How Are Thalassemias Diagnosed?")

Living With Thalassemias

Survival and quality of life have improved for people who have moderate or severe thalassemias. This is because:

More people are able to get blood transfusions now.
Blood screening has reduced the number of infections from blood transfusions. Also, treatments for other kinds of infections have improved.
Iron chelation treatments are available that are easier for some people to take.
Some people have been cured through blood and marrow stem cell transplants.

Living with thalassemia can be challenging, but several approaches can help you cope.

Follow Your Treatment Plan

Following the treatment plan your doctor gives you is important. For example, get blood transfusions as your doctor recommends, and take your iron chelation medicine as prescribed.

Iron chelation treatment can take time and be mildly painful. However, don't stop taking your medicine. The leading cause of death among people who have thalassemias is heart disease caused by iron overload. Iron buildup can damage your heart, liver, and other organs.

Several chelation treatments are now available, including injections and pills. Your doctor will talk with you about which treatment is best for you.

Take folic acid supplements if your doctor prescribes them. Folic acid is a B vitamin that helps build healthy red blood cells. Also, talk with your doctor about whether you need other vitamin or mineral supplements, such as vitamins A, C, or D or selenium.

Get Ongoing Medical Care

Keep your scheduled medical appointments, and get any tests that your doctor recommends.

These tests may include:

Monthly complete blood counts and tests for blood iron levels every 3 months
Yearly tests for heart function, liver function, and viral infections (for example, hepatitis B and C and HIV)
Yearly tests to check for iron buildup in your liver
Yearly vision and hearing tests
Regular checkups to make sure blood transfusions are working
Other tests as needed (such as lung function tests, genetic tests, and tests to match your tissues with a possible donor if a stem cell transplant is being considered)

Children who have thalassemias should receive yearly checkups to monitor their growth and development. The checkups include a physical exam, including a height and weight check, and any necessary tests.

Take Steps To Stay Healthy

Take steps to stay as healthy as possible. Follow a healthy eating plan and your doctor's instructions for taking iron supplements.

Get vaccinations as needed, especially if you've had your spleen removed. You may need vaccines for the flu, pneumonia, hepatitis B, and meningitis. Your doctor will advise you about which vaccines you need.

Watch for signs of infection (such as a fever) and take steps to lower your risk for infection (especially if you've had your spleen removed). For example:

Wash your hands often.
Avoid crowds during cold and flu season.
Keep the skin around the site where you get blood transfusions as clean as possible.
Call your doctor if a fever develops.

Emotional Issues and Support

If you or your child has thalassemia, you may have fear, anxiety, depression, or stress. Talk about how you feel with your health care team. Talking to a professional counselor also can help. If you’re very depressed, your doctor may recommend medicines or other treatments that can improve your quality of life.

Joining a patient support group may help you adjust to living with thalassemia. You can see how other people who have the same symptoms have coped with them. Talk with your doctor about local support groups or check with an area medical center.

Support from family and friends also can help relieve stress and anxiety. Let your loved ones know how you feel and what they can do to help you.

Some teens and young adults who have thalassemias may have a hard time moving from pediatric care to adult care. Doctors and other health professionals who care for these children might not be familiar with adult issues related to the disorder, such as certain complications.

Also, it might be hard for adults who have thalassemias to find doctors who specialize in treating the disorder. Ask your child's doctor to help you find a doctor who can care for your child when the time comes to make the switch. Planning and good communication can help this move go smoothly.

Clinical Trials

The National Heart, Lung, and Blood Institute (NHLBI) is strongly committed to supporting research aimed at preventing and treating heart, lung, and blood diseases and conditions and sleep disorders.

NHLBI-supported research has led to many advances in medical knowledge and care. For example, this research has uncovered some of the causes of blood disorders, as well as ways to prevent and treat these disorders.

Many questions remain about blood disorders, including thalassemias. The NHLBI continues to support research to learn more. For example, NHLBI-sponsored research includes studies that explore:

Ways to make gene therapy possible for treating people who have thalassemias
How to improve blood and marrow stem cell transplants for people who have thalassemias and other severe forms of anemia

Much of the NHLBI’s research depends on the willingness of volunteers to take part in clinical trials. Clinical trials test new ways to prevent, diagnose, or treat various diseases and conditions.

For example, new treatments for a disease or condition (such as medicines, medical devices, surgeries, or procedures) are tested in volunteers who have the illness. Testing shows whether a treatment is safe and effective in humans before it is made available for widespread use.

By taking part in a clinical trial, you can gain access to new treatments before they're widely available. You also will have the support of a team of health care providers, who will likely monitor your health closely. Even if you don't directly benefit from the results of a clinical trial, the information gathered can help others and add to scientific knowledge.

If you volunteer for a clinical trial, the research will be explained to you in detail. You'll learn about treatments and tests you may receive, and the benefits and risks they may pose. You'll also be given a chance to ask questions about the research. This process is called informed consent.

If you agree to take part in the trial, you'll be asked to sign an informed consent form. This form is not a contract. You have the right to withdraw from a study at any time, for any reason. Also, you have the right to learn about new risks or findings that emerge during the trial.

For more information about clinical trials related to thalassemias, talk with your doctor. You also can visit the following Web sites to learn more about clinical research and to search for clinical trials:

For more information about clinical trials for children, visit the NHLBI's Children and Clinical Studies Web page.

Links to Other Information About Thalassemias

NHLBI Resources

Anemia (Health Topics)
Iron-Deficiency Anemia (Health Topics)
Blood Transfusion (Health Topics)
Blood and Marrow Stem Cell Transplant (Health Topics)

Non-NHLBI Resources

Anemia (MedlinePlus)
Thalassemia (MedlinePlus)

Clinical Trials

Children and Clinical Studies
Clinical Trials (Health Topics)
Current Research (ClinicalTrials.gov)
NHLBI Clinical Trials
NIH Clinical Research Trials and You (National Institutes of Health)
ResearchMatch (funded by the National Institutes of Health)