Thalassemia is a general name for a group of inherited blood diseases that involve abnormalities in hemoglobin, the oxygen-carrying part of the red blood cells. Hemoglobin is mainly made up of two kinds of protein, called alpha and beta globin. Individuals with thalassemia do not produce enough of one (or occasionally both) of these proteins. As a result, their red blood cells may be abnormal and unable to carry enough oxygen throughout the body.
The two main types of thalassemia are called alpha and beta thalassemia:
- Individuals with alpha thalassemia do not produce enough alpha globin.
- Those with beta thalassemia do not produce enough beta globin.
There are a number of different forms of alpha and beta thalassemias, with symptoms ranging from mild to severe.
Thalassemia is among the most common genetic disorders worldwide (1). More than 100,000 babies worldwide are born each year with severe forms of thalassemia (2). Thalassemia occurs most frequently in people of Italian, Greek, Middle Eastern, Asian and African ancestry (3).
There are at least five main types of alpha thalassemia. These are most common in people of Southeast Asian, Indian, southern Chinese, Middle Eastern and African ancestry (4). There are four genes that control the production of alpha globin. The severity of the condition is determined by how many of these genes are missing or abnormal.
- Silent carrier, the mildest form, has one alpha globin gene missing or abnormal. Affected individuals generally have no symptoms, but they can pass on the genetic abnormality to their children.
- Alpha thalassemia minor (also called alpha thalassemia trait) has two missing or abnormal alpha globin genes. Affected individuals may have no symptoms or a mild anemia, but they can pass the condition on to their children.
- Hemoglobin H disease is caused by three missing or abnormal alpha globin genes (so there is one normal alpha globin gene). The condition causes abnormalities in red blood cells and rapid destruction of these cells. Most affected individuals have mild to moderate anemia and can live fairly normal lives. The anemia may temporarily worsen when individuals have a viral infection or when they are treated with certain medications (such as sulfa drugs) (5).
Some affected individuals eventually develop complications, such as an enlarged spleen or gallstones (5). Individuals with hemoglobin H disease should receive regular medical care to detect and treat these complications. Some may need occasional blood transfusions (6).
- Hemoglobin H-Constant Spring is a more severe form of hemoglobin H disease. Affected individuals have one normal alpha globin gene, plus a specific mutation (change) called Constant Spring on one of their three abnormal genes. People with this condition generally have moderate to severe anemia and often develop complications, such as an enlarged spleen. Some need blood transfusions from time to time, such as when they develop an illness with a fever, while others need more frequent transfusions (5, 6).
- Alpha thalassemia major, the most severe form, is caused when there are no alpha globin genes. Affected fetuses suffer from severe anemia, heart failure and fluid buildup. They usually are stillborn, but some die in the first hours after birth. In rare cases, babies diagnosed and treated before birth with blood transfusions have survived. These babies require lifelong blood transfusions (4, 5).
There are three main forms of beta thalassemia. These are most likely to affect people of Greek, Italian, Middle Eastern, Southeast Asian, southern Chinese and African descent (4). Two genes control the production of beta globin. Mutations on one or both of them can cause the disorder. The severity of the condition is determined by whether one or both beta globin genes carry a mutation and by the severity of the mutation.
- Thalassemia minor (also called thalassemia trait) is caused by a mutation on one beta globin gene. Most affected individuals have no symptoms, though some have mild anemia. Affected individuals can pass the abnormal gene on to their offspring.
- Thalassemia intermedia results from abnormalities in both beta globin genes. These gene abnormalities are generally less severe than those that cause thalassemia major. Affected children usually have mild to moderate anemia, and they may develop some of the complications seen in thalassemia major, including enlarged spleen and bone abnormalities. Many affected individuals require occasional or more frequent blood transfusions to reduce complications (1).
- Thalassemia major, the most severe form, results from severe mutations on both beta globin genes. It also is called Cooley's anemia, named after the doctor who first described it in 1925. Most affected children appear healthy at birth. However, during the first year or two of life, they become pale and fussy and have a poor appetite. They grow slowly and often develop jaundice (yellowing of the eyes and skin). Without treatment, they develop an enlarged spleen and liver, thinning bones that break easily, abnormal facial bones, frequent infections and heart problems, and they die in the first decade of life. Affected children require regular blood transfusions beginning in infancy.
Other forms of thalassemia include:
- E-beta thalassemia results from one beta globin gene carrying a thalassemia mutation (thalassemia minor) and one beta globin gene carrying a mutation that produces a variant form of hemoglobin called hemoglobin E. This condition is most common in people from Southeast Asia, including Cambodia, Vietnam and Thailand (4). Individuals who produce hemoglobin E generally are healthy or have only a mild anemia. However, those with E-beta thalassemia have mild to severe anemia, resembling beta thalassemia intermedia or beta thalassemia major (4).
- Hb S/beta thalassemia results from one beta globin gene carrying a thalassemia mutation (thalassemia minor) and one gene for sickle cell disease, another inherited anemia. It is most common in those of African or Mediterranean ancestry (4). Symptoms generally resemble those of sickle cell disease, including varying degrees of anemia, serious infections, pain and damage to vital organs.
Blood transfusions are used to treat severe forms of thalassemia. Children and adults with beta thalassemia major require regular transfusions. Some individuals with beta thalassemia intermedia, E-beta thalassemia and hemoglobin H-Constant Spring require transfusions from time to time, or sometimes more frequently. Some may need a transfusion if they develop a viral illness or other infection, which may cause anemia to become more severe. Health care providers may recommend more frequent transfusions if these individuals develop complications.
Children with severe thalassemia, such as beta thalassemia major, generally receive a transfusion every two to three weeks (4). Regular transfusions help keep hemoglobin levels near normal and help prevent many of the complications of thalassemia. This treatment improves the child's growth and well-being and usually prevents heart failure and bone deformities.
Unfortunately, repeated blood transfusions lead to a buildup of iron in the body. Iron buildup can damage the heart, liver and other organs. To help prevent organ damage, children and adults who receive regular transfusions are treated with a type of drug called an iron chelator. This drug binds to iron and helps the body get rid of excess iron.
Until recently, the only drug approved in the United States to prevent iron buildup was deferoxamine (Desferal or DFO). Individuals usually receive this drug over 8 to 12 hours, while they are sleeping, five to seven nights a week. A small pump delivers the drug through a needle placed under the skin. In November 2005, the U.S. Food and Drug Administration (FDA) approved the first oral iron chelating drug (Exjade or deferasirox) (7). This tablet is dissolved in water or juice and drunk once a day. Some individuals with severe thalassemia now can choose between these treatments.
Individuals with beta thalassemia major who are treated with regular blood transfusions and iron chelation often live 40 years or longer (2). The most common cause of death in these individuals is heart complications caused by iron buildup (8).
Children and adults with thalassemia must undergo tests to measure the level of iron in their bodies. Blood tests are used to measure the amount of iron in the blood. Unfortunately, blood tests are not very accurate in measuring the levels of iron in the heart and liver. Providers may recommend a yearly liver biopsy, a surgical procedure in which a small amount of liver tissue is removed and tested. A few medical centers have begun to use new, noninvasive imaging tests called SQUID and T2* to measure iron levels in the liver and heart (1, 2, 4). For more information on where these tests are available, contact the Cooley’s Anemia Foundation at firstname.lastname@example.org.
Some children with thalassemia can be cured with a bone marrow transplant. However, this form of treatment is most successful when a donor who is an exact genetic match is available. Generally, a sibling or other family member is most likely to be an exact match. The procedure can cure about 85 percent of children who have a fully matched family donor 9(). However, only about 30 percent of children with thalassemia have a family member who is a suitable donor (4). The procedure is risky and can result in death.
Recent studies suggest that using umbilical cord blood from a newborn sibling may be as effective as a bone marrow transplant (9). Like bone marrow, cord blood contains unspecialized cells called stem cells that produce all other blood cell.
All forms of thalassemia are inherited. The disease can not be caught from another person who has it. Thalassemia is passed on through parents who carry abnormal thalassemia genes in their cells.
When both parents carry alpha thalassemia genes, any child they have is at risk for inheriting a more severe form of this condition. Individuals who know they have one of these disorders, those with family histories of these disorders, and those from countries where they are common should consider consulting a genetic counselor to find out whether their children could be at risk. (Health care providers can provide referrals to genetic counselors, or individuals can find them by contacting a major medical center.)
When two individuals with beta thalassemia minor (carriers who each have a mutation on one beta globin gene) have children together, there is a 25 percent chance (1 in 4) that any child they have will inherit a thalassemia gene from each parent and have a severe form of the disease. There is:
- A 50 percent (2 in 4) chance that the child will inherit one of each kind of gene and have beta thalassemia minor like his parents
- A 25 percent (1 in 4) chance that the child will inherit two normal genes and be completely free of the disease.
The odds are the same for each pregnancy when both parents have the beta thalassemia minor.
Yes. Blood tests and family genetic studies can show whether an individual has any form of thalassemia. Newborn screening tests now identify many babies with thalassemia. In addition, prenatal testing using chorionic villus sampling (CVS) or amniocentesis can detect or rule out thalassemia in the fetus.
Women with milder forms of thalassemia usually have healthy pregnancies. Until recently, pregnancy was rare in women with beta thalassemia major. Several recent studies suggest that pregnancy appears safe for a woman with well-treated beta thalassemia major who does not have heart problems 9(10). Chelating drugs are usually stopped during pregnancy because it is not known whether they pose risks to the baby (4, 10). As long as a woman’s partner does not carry a gene for beta thalassemia, her children will not be at risk for thalassemia#although all will be carriers (beta thalassemia minor).
Scientists are working on better ways to remove excess iron from the body to prevent or delay iron overload. They are developing and testing new oral iron-chelating drugs and looking at whether combining one of these drugs with deferoxamine may be more effective than either treatment alone (1, 2).
Researchers are studying the effectiveness of certain drugs (including hydroxyurea, a drug used to treat sickle cell disease) in reactivating the genes for fetal hemoglobin. All humans produce a fetal form of hemoglobin before birth. After birth, natural genetic switches "turn off" production of fetal hemoglobin and "turn on" production of adult hemoglobin. Scientists are seeking ways to activate these genetic switches so that they can make the blood cells of individuals with beta thalassemia produce more fetal hemoglobin to make up for their deficiency of adult hemoglobin. Studies to date suggest that treatment with these drugs may be helpful for some patients with beta thalassemia intermedia (2).
Researchers also are exploring the possibility that dietary treatments, such as with vitamin E, may help reduce organ damage from iron buildup (1, 6). Others continue to improve bone marrow transplantation methods that may offer a cure to more children with thalassemia.
March of Dimes grantees have been among the many scientists seeking to develop an effective form of gene therapy that may offer a cure for thalassemia. Gene therapy may involve inserting a normal alpha or beta globin gene into the patient’s stem cells, possibly allowing these immature blood cells to produce normal red blood cells.
- Rund, D. and Rachmilewitz, E. Medical Progress: Beta-Thalassemia. New England Journal of Medicine, volume 353, number 11, September 15, 2005, pages 1135-1146.
- New York Academy of Sciences. Cooley’s Anemia Eighth Symposium. Posted 7/22/05, accessed 5/2/08.
- National Heart, Lung and Blood Institute. Thalassemias. Posted 1/08.
- Cooley’s Anemia Foundation. About Thalassemia. Updated 2007.
- Northern California Comprehensive Thalassemia Center. Alpha Thalassemia. Accessed 5/2/08.
- Cohen, A.R., et al. Thalassemia. Hematology 2004, American Society of Hematology, pages 14-34.
- Food and Drug Administration (FDA). FDA Approves First Oral Drug for Chronic Iron Overload. FDA News, November 9, 2005.
- Cunningham, M.J. Update on Thalassemia: Clinical Care and Complications. Pediatric Clinics of North America, volume 55, April 2008, pages 447-460.
- Di Bartolomeo, P., et al. Long-term Results of Survival in Patients with Thalassemia Major Treated with Bone Marrow Transplantation. American Journal of Hematology, February 13, 2008 (Epub ahead of print).
- American College of Obstetricians and Gynecologists (ACOG). Hemoglobinopathies in Pregnancy. ACOG Practice Bulletin, number 78, January 2007.
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Frequently Asked Questions
Can dad's exposure to chemicals harm his future kids?
Dad's exposure to harmful chemicals and substances before conception or during his partner's pregnancy can affect his children. Harmful exposures can include drugs (prescription, over-the-counter and illegal drugs), alcohol, cigarettes, cigarette smoke, chemotherapy and radiation. They also include exposure to lead, mercury and pesticides.
Unlike mom's exposures, dad's exposures do not appear to cause birth defects. They can, however, damage a man's sperm quality, causing fertility problems and miscarriage. Some exposures may cause genetic changes in sperm that may increase the risk of childhood cancer. Cancer treatments, like chemotherapy and radiation, can seriously alter sperm, at least for a few months post treatment. Some men choose to bank their sperm to preserve its integrity before they receive treatment. If you have a question about a specific exposure, contact the Organization of Teratology Information Specialists at www.otispregnancy.org.
Can Rh factor affect my baby?
The Rh factor may be a problem if mom is Rh-negative but dad is Rh-positive. If dad is Rh-negative, there is no risk.
If your baby gets her Rh-positive factor from dad, your body may believe that your baby's red blood cells are foreign elements attacking you. Your body may make antibodies to fight them. This is called sensitization.
If you're Rh-negative, you can get shots of Rh immune globulin (RhIg) to stop your body from attacking your baby. It's best to get these shots at 28 weeks of pregnancy and again within 72 hours of giving birth if a blood test shows that your baby is Rh-positive. You won't need anymore shots after giving birth if your baby is Rh-negative. You should also get a shot after certain pregnancy exams like an amniocentesis, a chorionic villus sampling or an external cephalic version (when your provider tries to turn a breech-position baby head down before labor). You'll also want to get the shot if you have a miscarriage, an ectopic pregnancy or suffer abdominal trauma.
Does cleft lip or cleft palate cause dental problems?
A cleft lip or cleft palate that extends into the upper gums (where top teeth develop) can cause your baby to have certain dental problems, including:
- Missing teeth
- Too many teeth
- Oddly shaped teeth
- Teeth that are out of position around the cleft
Every baby with a cleft lip or palate should get regular dental checkups by a dentist with experience taking care of children with oral clefts. Dental problems caused by cleft lip or palate usually can be fixed. If needed, your baby can get ongoing care by a team of experts, including:
- A dentist
- An orthodontist to move teeth using braces
- An oral surgeon to reposition parts of the upper jaw, if needed, and to fix the cleft
See also: Cleft lip and cleft palate
Does cleft lip or cleft palate cause ear problems?
Cleft lip does not cause ear problems.
Babies with cleft palate, however, are more likely than other babies to have ear infections and, in some cases, hearing loss. This is because cleft palate can cause fluid to build up in your baby’s middle ear. The fluid can become infected and cause fever and earache. If fluid keeps building up with or without infection, it can cause mild to moderate hearing loss.
Without treatment , hearing loss can affect your baby’s language development and may become permanent.
With the right care, this kind of hearing loss is usually temporary. Your baby’s provider may recommend:
- Having your baby’s ears checked regularly for fluid buildup
- Medicines for treating fluid buildup and ear infections
- Ear tubes if your baby has fluid in his ears over and over again. Ear tubes are tiny tubes that are inserted into the eardrum to drain the fluid and help prevent infections.
See also: Cleft lip and cleft palate
Does cleft lip or cleft palate cause problems with breastfeeding?
Babies with only a cleft lip usually don’t have trouble breastfeeding. Most of the time, they can breastfeed just fine. But they may need some extra time to get started.
Babies with cleft lip and palate or with isolated cleft palate can have:
- Trouble sucking strong enough to draw milk through a nipple
- Problems with gagging or choking
- Problems with milk coming through the nose while feeding
Most babies with cleft palate can’t feed from the breast. If your baby has cleft palate, he can still get the health benefits of breastfeeding if you feed him breast milk from a bottle. Your provider can show you how to express (pump) milk from your breasts and store breast milk.
Your baby’s provider can help you start good breastfeeding habits right after your baby is born. She may recommend:
- Special nipples and bottles that can make feeding breast milk from a bottle easier
- An obturator. This is a small plastic plate that fits into the roof of your baby’s mouth and covers the cleft opening during feeding.
See also: Cleft lip and cleft palate, Breastfeeding
Does cleft lip or cleft palate cause speech problems?
Children with cleft lip generally have normal speech. Children with cleft lip and palate or isolated cleft palate may:
- Develop speech more slowly
- Have a nasal sound when speaking
- Have trouble making certain sounds
Most children can develop normal speech after having cleft palate repair. However, some children may need speech therapy to help develop normal speech.
See also: Cleft lip and cleft palate
What are choroid plexus cysts?
The choroid plexus is the area of the brain that produces the fluid that surrounds the brain and spinal cord. This is not an area of the brain that involves learning or thinking. Occasionally, one or more cysts can form in the choroid plexus. These cysts are made of blood vessels and tissue. They do not cause intellectual disabilities or learning problems. Using ultrasound, a health care provider can see these cysts in about 1 in 120 pregnancies at 15 to 20 weeks gestation. Most disappear during pregnancy or within several months after birth and are no risk to the baby. They aren't a problem by themselves. But if screening tests show other signs of risk, they may indicate a possible genetic defect. In this case, testing with higher-level ultrasound and/or amniocentesis may be recommended to confirm or rule out serious problems.
What if I didn't take folic acid before pregnancy?
If you didn’t take folic acid before getting pregnant, it doesn't necessarily mean that your baby will be born with birth defects. If women of childbearing age take 400 micrograms of folic acid every day before and during early pregnancy, it may help reduce their baby’s risk for birth defects of the brain and spin called neural tube defects (NTDs). But it only works if you take it before getting pregnant and during the first few weeks of pregnancy, often before you may even know you’re pregnant.
Because nearly half of all pregnancies in the United States are unplanned, it's important that all women of childbearing age (even if they're not trying to get pregnant) get at least 400 micrograms of folic acid every day. Take a multivitamin with folic acid before pregnancy. During pregnancy, switch to a prenatal vitamin, which should have 600 micrograms of folic acid.
Last reviewed November 2012