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

Alpha-thalassemia



Other Names:
A-Thalassemia; Alpha thalassemia
This disease is grouped under:

Alpha-thalassemia is a blood disorder that reduces the body's production of hemoglobin. Affected people have anemia, which can cause pale skin, weakness, fatigue, and more serious complications. Two types of alpha-thalassemia can cause health problems: the more severe type is known as Hb Bart syndrome; the milder form is called HbH disease. Hb Bart syndrome may be characterized by hydrops fetalis; severe anemia; hepatosplenomegaly; heart defects; and abnormalities of the urinary system or genitalia. Most babies with this condition are stillborn or die soon after birth. HbH disease may cause mild to moderate anemia; hepatosplenomegaly; jaundice; or bone changes. Alpha-thalassemia typically results from deletions involving the HBA1 and HBA2 genes. The inheritance is complex, and can be read about here.[1] No treatment is effective for Hb Bart syndrome. For HbH disease, occasional red blood cell transfusions may be needed.[2]
Last updated: 7/29/2015

This table lists symptoms that people with this disease may have. For most diseases, symptoms will vary from person to person. People with the same disease may not have all the symptoms listed. This information comes from a database called the Human Phenotype Ontology (HPO) . The HPO collects information on symptoms that have been described in medical resources. The HPO is updated regularly. Use the HPO ID to access more in-depth information about a symptom.

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Medical Terms Other Names
Learn More:
HPO ID
80%-99% of people have these symptoms
Abnormal hemoglobin 0011902
Microcytic anemia 0001935
5%-29% of people have these symptoms
Abnormality of immune system physiology 0010978
Cholelithiasis
Gallstones
0001081
Cognitive impairment
Abnormality of cognition
Cognitive abnormality
Cognitive defects
Cognitive deficits
Intellectual impairment
Mental impairment
[ more ]
0100543
Hemolytic anemia 0001878
Hydrops fetalis 0001789
Hypersplenism 0001971
Jaundice
Yellow skin
Yellowing of the skin
[ more ]
0000952
Myelodysplasia 0002863
Splenomegaly
Increased spleen size
0001744
Percent of people who have these symptoms is not available through HPO
Hypochromic microcytic anemia 0004840
Reduced alpha/beta synthesis ratio 0011907
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Last updated: 7/1/2020

The inheritance of alpha-thalassemia is complex because the condition involves two genes: HBA1 and HBA2. People have two copies of the HBA1 gene and two copies of the HBA2 gene in each cell. Each copy is called an allele. Therefore, there are 4 alleles that produce alpha-globin, the protein that results from these genes. For each of the 2 genes, one allele is inherited from a person's father, and the other is inherited from a person's mother - so each person inherits 2 alleles from each parent. The different types of alpha-thalassemia result from the loss of some or all of these alleles.

If both parents are missing at least one alpha-globin allele, each of their children are at risk of having Hb Bart syndrome or hydrops fetalis, hemoglobin H (HbH) disease, or alpha-thalassemia trait. The precise risk depends on how many alleles are missing and which combination of the HBA1 and HBA2 genes is affected.[1]

In most cases:
  • a person with 1 mutated allele is a carrier and has no signs or symptoms
  • a person with 2 mutated alleles may have mild signs or symptoms of alpha-thalassemia (called alpha-thalassemia minor, or alpha-thalassemia trait)
  • a person with 3 mutated alleles has moderate to severe symptoms (called HbH disease)

When there are 4 mutated alleles, the condition is called alpha-thalassemia major or hydrops fetalis. In these cases, an affected fetus usually does not survive to birth, or an affected newborn does not survive long after birth.[3]

Last updated: 7/29/2015

Treatment of alpha-thalassemia often includes blood transfusions to provide healthy blood cells that have normal hemoglobin.  Bone marrow transplant has helped to cure a small number of individuals with severe alpha-thalassemia.[4]
Last updated: 1/25/2012

FDA-Approved Treatments

The medication(s) listed below have been approved by the Food and Drug Administration (FDA) as orphan products for treatment of this condition. Learn more orphan products.

  • Deferasirox (Brand name: Exjade) - Manufactured by Novartis Pharmaceuticals Corporation
    FDA-approved indication: 1. Treatment of chronic iron overload in patients 10 years of age and older with non-transfusion-dependent thalassemia (NTDT) syndromes and with a liver iron concentration (LIC) of at least 5 milligrams of iron per gram of liver dry weight (mg Fe/g dw) and a serum ferritin greater than 300 mcg/L. 2. Also treatment of chronic iron overload due to blood transfusions (transfusional hemosiderosis) in patients 2 years of age or older.
    National Library of Medicine Drug Information Portal
    Medline Plus Health Information

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


Related diseases are conditions that have similar signs and symptoms. A health care provider may consider these conditions in the table below when making a diagnosis. Please note that the table may not include all the possible conditions related to this disease.

Conditions with similar signs and symptoms from Orphanet
Differential diagnosis should include iron deficiency anemia and defects in heme synthesis. An acquired form known as alpha-thalassemia-myelodysplastic syndrome (ATMDS; see this term) has been described mainly in adult males and should also be considered. It is characterized by myelodysplasia (MD) associated with HbH.
Visit the Orphanet disease page for more information.

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 Alpha-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

  • Genetics Home Reference (GHR) contains information on Alpha-thalassemia. This website is maintained by the National Library of Medicine.
  • 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 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.
  • The Screening, Technology And Research in Genetics (STAR-G) Project has a fact sheet on this condition, which was written specifically for families that have received a diagnosis as a result of newborn screening. This fact sheet provides general information about the condition and answers questions that are of particular concern to parents.

In-Depth Information

  • GeneReviews provides current, expert-authored, peer-reviewed, full-text articles describing the application of genetic testing to the diagnosis, management, and genetic counseling of patients with specific inherited conditions.
  • 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.
  • Online Mendelian Inheritance in Man (OMIM) is a catalog of human genes and genetic disorders. Each entry has a summary of related medical articles. It is meant for health care professionals and researchers. OMIM is maintained by Johns Hopkins University School of Medicine. 
  • Orphanet is a European reference portal for information on rare diseases and orphan drugs. Access to this database is free of charge.
  • PubMed is a searchable database of medical literature and lists journal articles that discuss Alpha-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. Alpha thalassemia. Genetics Home Reference. August 2009; http://ghr.nlm.nih.gov/condition/alpha-thalassemia. Accessed 1/23/2012.
  2. Alpha-Thalassemia. GeneReviews. July 15, 2008; http://www.ncbi.nlm.nih.gov/books/NBK1435/. Accessed 1/23/2012.
  3. Thalassemia. Mayo Clinic. January 2, 2014; http://www.mayoclinic.org/diseases-conditions/thalassemia/basics/causes/con-20030316.
  4. National Heart Lung and Blood Institute. Thalassemias. How Are Thalassemias Treated?. August 1, 2010; http://www.nhlbi.nih.gov/health/health-topics/topics/thalassemia/treatment.html. Accessed 1/23/2012.