National Center for Advancing and Translational Sciences Genetic and Rare Diseases Information Center, a program of the National Center for Advancing and Translational Sciences

Thalassemia

Thalassemia is an inherited blood disorder that reduces the production of functional hemoglobin (the protein in red blood cells that carries oxygen). This causes a shortage of red blood cells and low levels of oxygen in the bloodstream, leading to a variety of health problems.[1] There are two main types of thalassemia, alpha thalassemia and beta thalassemia. Signs and symptoms vary but may include mild to severe anemia, paleness, fatigue, yellow discoloration of skin (jaundice), and bone problems.[2] Beta thalassemia is caused by changes (mutations) in the HBB gene while alpha thalassemia is caused by mutations in the HBA1 and/or HBA2 genes. Both are inherited in an autosomal recessive manner.[3][4] Treatment depends on the type and severity of the condition but may include blood transfusions and/or folic acid supplements.[5][2]
Last updated: 1/1/2015
The signs and symptoms vary depending on the severity of the thalassemia. For example, people affected by milder forms of thalassemia can develop mild anemia or may have no signs or symptoms of the condition at all. Intermediate forms of thalassemia can cause mild to moderate anemia and may be associated with other health problems such as slowed growth, delayed puberty, bone problems and/or an enlarged spleen. In addition to the signs and symptoms seen in intermediate thalassemia, people with severe forms of thalassemia may also experience severe anemia, poor appetite, paleness, dark urine, yellow discoloration of skin (jaundice), and enlarged liver or heart.[2][1][5]

For more information on the signs and symptoms by type of thalassemia, please click here.
Last updated: 1/1/2015
There are two main types of thalassemia, alpha thalassemia and beta thalassemia, which each affect a different part of hemoglobin (the protein in red blood cells that carries oxygen). Hemoglobin is made up of two different components (subunits): beta globin and alpha globin. The HBB gene provides instructions for making beta globin, while the HBA1 and HBA2 genes provide instructions for making alpha globin. Each person has two copies of each of these genes, one inherited from the mother and one from the father. Changes (mutations) in the HBB gene lead to reduced levels of beta globin and cause beta thalassemia. Loss (deletion) of some or all of the HBA1 and/or HBA2 genes results in a shortage of alpha globin, leading to alpha thalassemia.[3][4]
Last updated: 1/2/2015
In general, thalassemia is inherited in an autosomal recessive manner; however, the inheritance can be quite complex as multiple genes can influence the production of hemoglobin.[3][4]

Most people affected by beta thalassemia have mutations in both copies of the HBB gene in each cell. The parents of an affected person usually each carry one mutated copy of the gene and are referred to as carriers. Carriers typically do not show signs or symptoms of the condition; although some carriers of beta thalassemia develop mild anemia. When two carriers of an autosomal recessive condition have children, each child has a 25% (1 in 4) risk to have the condition, a 50% (1 in 2) risk to be a carrier like each of the parents, and a 25% chance to not have the condition and not be a carrier.[3]

The inheritance of alpha thalassemia is complicated by the fact that mutations in two different genes (HBA1 and HBA2) are associated with the condition. People have two copies of the HBA1 gene and two copies of the HBA2 gene in each cell. For each gene, one copy is inherited from the mother and one is inherited from the father. If each parent is missing at least one gene copy, their children are at risk for having alpha thalassemia. However, the exact risk and the severity of each child's condition depends on how many gene copies are lost (deleted) and which combination of the HBA1 and HBA2 genes are affected.[4]
Last updated: 1/2/2015
Yes, genetic testing is available for HBB, HBA1 and HBA2, the genes known to cause thalassemia.[3][4] Carrier testing for at-risk relatives and prenatal testing are possible if the disease-causing mutations in the family are known.

The Genetic Testing Registry (GTR) is a centralized online resource for information about genetic tests. It has additional information on genetic testing for alpha thalassemia and beta thalassemia. The intended audience for the GTR is health care providers and researchers. Patients and consumers with specific questions about a genetic test should contact a health care provider or a genetics professional.
Last updated: 1/2/2015

Testing Resources

  • The Genetic Testing Registry (GTR) provides information about the genetic tests for this condition. The intended audience for the GTR is health care providers and researchers. Patients and consumers with specific questions about a genetic test should contact a health care provider or a genetics professional.
The best treatment options depend on the severity of thalassemia. People affected by a mild form often need little to no treatment, while people with intermediate to severe thalassemias may require frequent blood transfusions, iron chelation therapy (treatments to remove excess iron from the body), and/or folic acid supplementation.[2][1]

For more information on the treatment of thalassemia, please click here.
Last updated: 1/4/2015
The long-term outlook (prognosis) for people with thalassemia depends on the type and severity of the condition. For example, severe thalassemia can cause early death due to heart failure, while less severe forms of thalassemia often do not shorten lifespan.[1] Fortunately, improved treatment options have resulted in increased survival and better quality of life for people affected by moderate to severe thalassemia.[2]
Last updated: 1/2/2015

If you need medical advice, you can look for doctors or other healthcare professionals who have experience with this disease. You may find these specialists through advocacy organizations, clinical trials, or articles published in medical journals. You may also want to contact a university or tertiary medical center in your area, because these centers tend to see more complex cases and have the latest technology and treatments.

If you can’t find a specialist in your local area, try contacting national or international specialists. They may be able to refer you to someone they know through conferences or research efforts. Some specialists may be willing to consult with you or your local doctors over the phone or by email if you can't travel to them for care.

You can find more tips in our guide, How to Find a Disease Specialist. We also encourage you to explore the rest of this page to find resources that can help you find specialists.

Healthcare Resources

Research helps us better understand diseases and can lead to advances in diagnosis and treatment. This section provides resources to help you learn about medical research and ways to get involved.

Clinical Research Resources

  • ClinicalTrials.gov lists trials that are related to Thalassemia. Click on the link to go to ClinicalTrials.gov to read descriptions of these studies.

    Please note: Studies listed on the ClinicalTrials.gov website are listed for informational purposes only; being listed does not reflect an endorsement by GARD or the NIH. We strongly recommend that you talk with a trusted healthcare provider before choosing to participate in any clinical study.

Support and advocacy groups can help you connect with other patients and families, and they can provide valuable services. Many develop patient-centered information and are the driving force behind research for better treatments and possible cures. They can direct you to research, resources, and services. Many organizations also have experts who serve as medical advisors or provide lists of doctors/clinics. Visit the group’s website or contact them to learn about the services they offer. Inclusion on this list is not an endorsement by GARD.

Organizations Supporting this Disease

Living with a genetic or rare disease can impact the daily lives of patients and families. These resources can help families navigate various aspects of living with a rare disease.

Financial Resources

  • Patient Access Network Foundation (PAN Foundation) has Assistance Programs for those with health insurance who reside in the United States. The disease fund status can change over time, so you may need to check back if funds are not currently available. 

These resources provide more information about this condition or associated symptoms. The in-depth resources contain medical and scientific language that may be hard to understand. You may want to review these resources with a medical professional.

Where to Start

  • You can obtain information on this topic from the Centers for Disease Control and Prevention (CDC). The CDC is recognized as the lead federal agency for developing and applying disease prevention and control, environmental health, and health promotion and education activities designed to improve the health of the people of the United States.
  • The Mayo Clinic Web site provides further information on Thalassemia.
  • MedlinePlus was designed by the National Library of Medicine to help you research your health questions, and it provides more information about this topic.
  • The Merck Manual provides information on this condition for patients and caregivers. 
  • The National Heart, Lung, and Blood Institute (NHLBI) has information on this topic. NHLBI is part of the National Institutes of Health and supports research, training, and education for the prevention and treatment of heart, lung, and blood diseases.
  • The National Human Genome Research Institute's (NHGRI) website has an information page on this topic. NHGRI is part of the National Institutes of Health and supports research on the structure and function of the human genome and its role in health and disease.

In-Depth Information

  • The Merck Manual for health care professionals provides information on Thalassemia.
  • The Monarch Initiative brings together data about this condition from humans and other species to help physicians and biomedical researchers. Monarch’s tools are designed to make it easier to compare the signs and symptoms (phenotypes) of different diseases and discover common features. This initiative is a collaboration between several academic institutions across the world and is funded by the National Institutes of Health. Visit the website to explore the biology of this condition.
  • PubMed is a searchable database of medical literature and lists journal articles that discuss Thalassemia. Click on the link to view a sample search on this topic.

Questions sent to GARD may be posted here if the information could be helpful to others. We remove all identifying information when posting a question to protect your privacy. If you do not want your question posted, please let us know.

  1. Thalassemia. MedlinePlus. February 2014; http://www.nlm.nih.gov/medlineplus/ency/article/000587.htm.
  2. Explore Thalassemias. National Heart, Lung, and Blood Institute. July 2012; http://www.nhlbi.nih.gov/health/health-topics/topics/thalassemia.
  3. Beta thalassemia. Genetics Home Reference. July 2009; http://ghr.nlm.nih.gov/condition/beta-thalassemia. Accessed 12/5/2010.
  4. Alpha thalassemia. Genetics Home Reference. August 2009; http://ghr.nlm.nih.gov/condition/alpha-thalassemia. Accessed 1/23/2012.
  5. Hassan M Yaish, MD. Pediatric Thalassemia. Medscape Reference. April 2013; http://emedicine.medscape.com/article/958850-overview.