Inherited red blood cell disorders
Beta thalassemia major (transfusion-dependent)
Also called Transfusion-dependent beta-thalassemia
If you or someone you love has just heard this diagnosis, start here. This guide explains what the condition is, how it is usually treated and where a transplant fits.
Transfusion-dependent beta-thalassemia is an inherited hemoglobin disorder that requires regular red-cell transfusions. Iron management is essential alongside transfusion. A donor transplant or an approved gene therapy may offer transfusion independence for selected people, but each requires careful assessment and long-term care.
Other names and abbreviations
TDT, β-thalassemia major, BT major, transfusion-dependent thalassemia, Cooley anemia, beta thalassemia major, Beta-thalassemia major, Thalassemia major, Mediterranean anemia
In short
- Transfusion-dependent beta thalassemia is an inherited condition that can cause severe anemia. The body makes too little of one part of hemoglobin.
- Care centers on regular red cell transfusions and medicine to remove the extra iron they bring. Checks of the heart, liver and other organs are also a key part of care.
- For selected people, a transplant from a matched sibling or unrelated donor may end the need for transfusions. In some countries, gene therapy using a person's own cells may do the same for selected people.
Jump to a section
Underlined words open a short explanation. See all terms
Where transplant fits
A matched sibling or suitable unrelated donor can provide an established transplantA treatment that gives a patient healthy blood-forming stem cells through a vein. The cells travel to the bone marrow and replace faulty marrow or marrow damaged by treatment. They can come from the patient or a donor. route. Approved autologousComing from the patient's own body. In an autologous transplant, the patient's own stem cells are collected and stored, then given back after high-dose treatment. It does not use a donor. gene therapiesTreatment that adds a new gene or restores the work of a faulty or missing one. For some inherited disorders, the patient's own blood-forming stem cells are changed in a lab and given back. It does not use a donor. use the patient’s own cells instead. Treatment choice reflects health, iron burden, donor options, access and the person’s priorities.
Treatment depends on the exact diagnosis, disease stage, prior treatment and the person’s health.
Key facts
- Who it affects
- Severe beta-thalassemia often becomes evident in early childhood. Transfusion dependence describes clinical need and is not the same as beta-thalassemia carrier status.
- How common
- About 2.3 in every 100,000 birthsBeta thalassemia major and related combined forms (not counting sickle beta thalassemia), California births 2001–2011; as reported in a 2021 paper on U.S. newborn screening. Little is known about other U.S. states. Source: How common
- How it is passed on
- Autosomal recessive: a child is affected when both parents pass on a changed gene.
- Cells used in a transplant
- Allogeneic blood-forming stem cells from an appropriate donor, or the patient’s own gene-modified stem cells for an eligible autologous gene therapy.
- Where a donor fits
- Cell or gene therapy options
The condition
What it is
Hemoglobin, the protein in red blood cells that carries oxygen, is built from two kinds of parts called alpha globin and beta globin. In beta-thalassemia, the body makes too little beta globin. Young red cells are damaged while they form in the bone marrowThe soft, spongy tissue in the center of most bones. Red bone marrow holds the blood-forming stem cells that make red blood cells, white blood cells and platelets., and red cells in the blood can break down early. The result can be severe anemia.
“TransfusionPutting blood, or parts of blood such as red cells or platelets, into a person's bloodstream through a vein. Some people with blood disorders need regular transfusions.-dependent” describes a clinical need for regular transfusions, rather than a single genetic variant. Severity and transfusion needs can change, and not all beta-thalassemia is transfusion dependent.
Marked as affected: red blood cells.
- Blood stem cell, In the bone marrow
- Myeloid line
- Red blood cells, Affected
- Platelets
- Granulocytes
- Monocytes
- Lymphoid line
- B cells
- Plasma cells, Develop from B cells
- T cells
- NK cells, Natural killer cells
- Myeloid line
What causes it
Beta-thalassemia is caused by changes in the HBB gene, which holds the instructions for making beta globin. Severe forms usually involve changes in both copies of the gene. How much beta globin the body can still make, and other inherited factors, affect how serious it is.
The condition occurs worldwide. Carrier testingSomeone with one changed copy of a disease gene who has no symptoms or only mild ones. A carrier can pass the change to a child. A child with a changed copy from each parent usually has the condition. and genetic counseling help explain family risks. Beta-thalassemia trait often causes mild or no anemia and is not the same as transfusion-dependent disease.
- Parent: Carrier: one changed copy, not affected
- Parent: Carrier: one changed copy, not affected
- 1 in 4: Affected, Two changed copies
- 2 in 4: Carrier, One changed copy, like the parents
- 1 in 4: Neither affected nor a carrier, Two working copies
The chances are the same for each pregnancy.
Common severe forms involve variants in both copies of HBB. In a small percentage of families, a variant is inherited in an autosomal dominant manner.
- Changed copy of the gene
- Working copy
Symptoms and effects
Inadequately treated anemia can affect energy, growth and development. Increased marrow activity and an enlarged spleen can cause additional problems.
Regular transfusion controls anemia but adds iron that can accumulate in the heart, liver and endocrine organs. Iron-related complications can occur without obvious early symptoms, which is why monitoring and treatment remain necessary even when transfusions improve how someone feels.
A simple drawing of a body. Can be affected: hormone glands, heart, liver and spleen.
Can be affected
- Hormone glands: Iron build-up
- Heart: Iron build-up
- Liver: Iron build-up
- Spleen: Enlarged spleen
This shows the parts of the body the condition can affect. Most people have only some of these, and the drawing says nothing about how severe any of them will be.
Diagnosis and treatment
How beta thalassemia major is diagnosed
Severe forms of thalassemia usually show up before a child turns 2. Diagnosis starts with blood tests. A complete blood count (CBC) measures hemoglobin and red blood cells. Special hemoglobin tests show which types of hemoglobin are in the blood. A gene test can then show the exact type of thalassemia. Doctors also ask about family history, because thalassemia is inherited.
Beta thalassemia is not a core condition on the U.S. newborn screeningTests for serious conditions, often done before a newborn baby leaves the hospital. Some use a few drops of blood from the baby's heel. If a result points to a condition, more tests check for it. list. But the screen every U.S. program uses to find sickle cell disease can also show when a baby makes little or no adult hemoglobin (hemoglobin A). That can be an early clue. In a survey of U.S. programs published in 2021, 39 of the 46 programs that answered said they report some form of possible beta thalassemia. Test methods, cutoffs and follow-up varied widely.
Finding it early also gives parents a chance for genetic counseling before another pregnancy.
Newborn screening for beta thalassemia is not the same everywhere. Methods, cutoffs and follow-up differ from state to state.
How it is treated
Care centers on regular transfusion, iron chelation and monitoring for organ complications. The transfusion schedule and chelation medicine are tailored to the individual. Iron assessment uses blood tests and, where appropriate, imaging rather than a single ferritin measurement alone.
Luspatercept can reduce transfusion needs in some adults with beta-thalassemia. Mitapivat, marketed as Aqvesme, is FDA approved for anemia in adults with alpha- or beta-thalassemia. Its risks and monitoring requirements, including liver safety, need consideration; adult US approval does not establish access or suitability elsewhere.
A donor stem cell transplant, also called an allogeneic transplant, replaces the person’s blood-forming cellsYoung cells that can grow into every type of blood cell: red cells that carry oxygen, white cells that fight infection and platelets that help blood clot. They are found in the bone marrow and the bloodstream. with a donor’s cells. It is an established treatment that can cure the disease for some people. A suitable brother or sister or a well-matched unrelated donor may be used. Results depend on several things, including organ damage from iron that has already happened. No single age cutoff predicts how one person will do.
In the United States, Zynteglo adds a functional beta-globin gene to the patient’s own stem cells. Casgevy edits the patient’s cells to increase fetal hemoglobin. Since July 2026, it has been approved for people aged 2 and older. Both have specific indications and require conditioningTreatment that prepares a patient for a stem cell transplant. It can include chemotherapy, radiation or antibody medicines. It makes room in the marrow for the new cells, helps prevent rejection and can kill cancer cells. chemotherapy. Neither requires a registry donor.
Kinds of treatment described for beta thalassemia major (transfusion-dependent): supportive care, medicines (for some people), a donor stem cell transplant (for some people) and gene therapy with the person’s own cells (for some people).
After diagnosis, the options described here
Supportive care
Regular red cell transfusions, with medicine to remove the extra iron they bring and checks of the heart and liver.
Medicines, For some people
Luspatercept can reduce transfusion needs in some adults.
Donor stem cell transplant, For some people
A transplant from a suitable brother or sister or a well-matched unrelated donor can cure the disease for some people.
What a transplant involvesGene therapy with the person’s own cells, For some people
In some countries, approved gene therapies use the person’s own stem cells and need no registry donor.
These are the kinds of treatment this page describes, not a plan. Which ones fit, in what order and whether they are combined differs from person to person.
When transplant specialists are usually consulted
U.S. transplant guidelines (NMDP and ASTCT) advise a transplant center consultation at diagnosis for transfusion-dependent thalassemia.
Read the guidanceWhat a transplant involves
- Step 1
: Finding a donor
Relatives are tested first to see whether their tissue type (HLA) matches. If none match, the team searches donor registries and cord blood banks.
- Step 2
: Conditioning
Chemotherapy, sometimes with radiation, prepares the body for the new cells.
- Step 3
: Transplant day, Day 0
The donor’s cells are given through a vein, like a transfusion.
- Step 4
: Engraftment
The new cells settle in the marrow and start making blood cells, usually within weeks.
- Step 5
: Recovery
The immune system rebuilds over months. The team watches for infection, graft-versus-host disease (donor immune cells attacking the body) and relapse.
Daily life and the donor’s role
Living with the condition
Regular treatment can mean scheduling transfusions, taking chelation and attending scans and specialist appointments over many years. This day-to-day burden is part of weighing treatment choices, along with medical benefits and harms.
Before transplant or gene therapy, discussion includes fertility preservation, conditioning toxicity, infection, recovery and long-term monitoring. Donor transplantation also carries graft-versus-host diseaseA complication of a donor transplant. The donated cells see the patient's healthy tissues as foreign and attack them, especially the skin, liver and gut. It can start soon after transplant or much later and can be life-threatening. risk. Iron overload may still need treatment after transfusions stop.
The donor’s role
When no suitable family donor is available, an unrelated donor can make a transplant possible. Related donors need assessment of their hemoglobin status and overall suitability in addition to HLA matchingMarkers on most cells that make up a person's tissue type. Doctors test a patient's and donor's HLA to see how well they match. The more markers they share, the better the chance the body accepts the donor's cells..
A donor match is one part of a treatment decision. Some people continue transfusion-based care or receive other medicines; some pursue gene therapy using their own cells. Gene therapy does not need a registry donor.
The person’s own cells
Autologous transplant, no donor
Collected from the person before treatment, then given back.
A relative
Donor transplant (allogeneic)
A brother or sister may be a full match. Parents and children can be half-matched donors.
An unrelated volunteer
Donor transplant (allogeneic)
Found through a donor registry.
Donated cord blood
Donor transplant (allogeneic)
Collected from a baby’s umbilical cord after birth and stored in a public bank.
Looking ahead
Looking ahead
Outlook for beta thalassemia major
The outlook for beta thalassemia major has improved a great deal where regular transfusions and iron-removal medicine (chelation) are available. In a large Italian study, survival to age 30 was higher for people born in later years. Deaths from heart disease fell steadily from 2000 onward.
Regular transfusions bring extra iron, which can build up and cause life-threatening problems. In the Italian study, heart disease was the most common cause of death. A very high level of stored iron in the blood (ferritin above 1,000 ng/mL) and heart disease were both strongly linked to a higher risk of death. Chelation medicine is used to remove the extra iron.
A donor transplantComing from another person. In an allogeneic, or donor, transplant, the stem cells come from a relative or an unrelated volunteer whose cells are a close enough match to the patient's. can end the need for transfusions. In a large European registry, results were best when the donor was a matched brother or sister and when the transplant was done before about age 14. Gene therapies that use a person's own cells are another option in some countries. None of these figures can predict how one person will do.
About these numbers. Each one says which group of people it comes from, and the place and years where the source gives them. It describes what happened across that group, not what will happen to any one person. And a figure measured among people who had a transplant is not the same as the number of people who need one.
- 93.3%Survival to age 30
People with transfusion-dependent beta thalassemia major born 1985–1997, part of a cohort of 709 patients cared for at 7 major centers in Italy and followed through 2020 (American Journal of Hematology, 2023). The figure was 83.6% for those born 1970–1974.
Read the source: Survival to age 30 - 81%Thalassemia-free survival 2 years after a donor transplant
1,493 people with thalassemia major (91% under 18) transplanted in Europe 2000–2010, EBMT hemoglobinopathy registry. It was 83% when the donor was a matched brother or sister. Not a figure for everyone with the condition.
Read the source: Thalassemia-free survival 2 years after a donor transplant
These studies describe people cared for at specialist centers. The Italian authors link better survival to good access to care, which differs around the world.
Common questions
Can transfusion-dependent beta-thalassemia be cured?
For some people, yes. A blood stem cell transplant from a suitable brother or sister or a well-matched unrelated donor is an established, potentially curative treatment. In the US, approved gene therapies that use a person’s own modified stem cells are another option for some people who need regular transfusions. Each option has its own risks and eligibility rules. Built-up iron may still need treatment after a transplant.
Is beta-thalassemia inherited?
Yes. Severe forms are usually inherited in an autosomal recessive pattern, which means both copies of the HBB gene are changed. The parents of an affected child usually each carry one changed copy and typically do not have the condition’s signs. Beta-thalassemia occurs worldwide. Carrier testing and genetic counseling can help families understand their risks.
Is beta-thalassemia trait the same as transfusion-dependent thalassemia?
No. Beta-thalassemia trait, also called thalassemia minor, means one copy of the HBB gene is changed. It often causes mild or no anemia. Transfusion-dependent beta-thalassemia usually involves both copies and causes severe anemia that needs regular red-cell transfusions. Older names for this severe form include thalassemia major and Cooley anemia.
Does transfusion-dependent beta-thalassemia need a bone marrow transplant?
Not always. Regular transfusions with iron-removal medicine, called chelation, remain central to care, and some adults can use medicines that lower transfusion needs. A donor transplant is one established option for selected people, and gene therapy using a person’s own cells is another. The choice depends on health, iron levels, donor options, access and the person’s own priorities.
Can a brother or sister be the donor for beta-thalassemia?
Yes, a matched brother or sister is an established donor option. A related donor is checked for hemoglobin status and overall suitability, not only for a tissue (HLA) match. When no suitable family donor is available, a well-matched unrelated donor from a registry offers an established path. Approved gene therapies use the patient’s own cells and need no donor.
Is beta-thalassemia the same as alpha thalassemia?
No. Both are inherited forms of thalassemia, but they affect different parts of hemoglobin. Beta-thalassemia comes from changes in the HBB gene. Alpha thalassemia depends on how many of the four alpha-globin genes are missing or changed. When all four are affected, the result is alpha thalassemia major, a severe form that begins before birth. A donor stem cell transplant is also used for it. The approved gene therapies are for beta-thalassemia; none is approved for alpha thalassemia.
Why the details matter
Iron overload may still need treatment after a person no longer needs transfusions. Gene addition and gene editing are different technologies.
For your next appointment
Beta thalassemia major (transfusion-dependent)
From the Jada Bascom Foundation disease library, jadabascomfoundation.org. Printed .
Questions to bring to your care team
- Should our other children have HLA typing to see if one could be a matched donor, and be checked for thalassemia trait?
- How are iron levels in the heart and liver checked, and how often?
- Is gene therapy, such as Casgevy or Zynteglo, an option here, and how does it compare with a donor transplant?
- What can be done to protect fertility before conditioning chemotherapy?
- What is the exact name of the diagnosis or subtype, and what does it mean for treatment?
- What is the goal of each treatment you are suggesting?
- Where can our family find support during treatment?
A one-page list to take to the next appointment, with room for notes.
Supporting someone with a diagnosisSupport for patients and families
These independent organizations offer information and support. JBF is not affiliated with them.
- Cooley's Anemia Foundation US nonprofit working to help every person with thalassemia live a longer, fuller life, and to find a cure.United States
- Thalassaemia International Federation (TIF) Patient-founded international federation working for equal access to quality care for every patient with thalassemia and other hemoglobin disorders.Worldwide (Cyprus-based)
- UK Thalassaemia Society UK charity that educates people with thalassemia and their parents, with publications, videos and information in several languages.United Kingdom
Sources and further reading
- Beta-Thalassemia
GeneReviews, University of Washington / NCBI Bookshelf, Accessed 2026-09-05 - Beta thalassemia
MedlinePlus Genetics, US National Library of Medicine, Accessed 2026-09-05 - CASGEVY: indication and current prescribing information
FDA, Accessed 2026-09-05 - ZYNTEGLO: indication and current prescribing information
FDA, Accessed 2026-09-05 - FDA approves first oral treatment for anemia in thalassemia
FDA, Accessed 2026-09-05 - REBLOZYL prescribing information
FDA, Accessed 2026-09-05 - 2025 EBMT practice recommendations for transplantation and CAR-T
EBMT, 2025 - FDA approves first gene therapy for young children with sickle cell disease (Casgevy, ages 2 and older)
US Food and Drug Administration, 2026-07-01; accessed 2026-09-26 - Thalassemia - Treatment
NHLBI, NIH, 2022-06-01 - Cure for thalassemia major – from allogeneic hematopoietic stem cell transplantation to gene therapy
Haematologica (Srivastava A, Shaji RV), 2017 - Thalassemia - Diagnosis
NHLBI, NIH, 2022-06-01 - Newborn Screening Practices for Beta-Thalassemia in the United States
International Journal of Neonatal Screening (Bender MA et al.), 2021 - Allogeneic hematopoietic stem cell transplantation in congenital hemoglobinopathies with myeloablative conditioning and rabbit anti-thymocyte globulin
Blood Research (Park B-K et al.), 2018 - Overall and complication-free survival in a large cohort of patients with β-thalassemia major followed over 50 years
American Journal of Hematology (Forni and colleagues), abstract via Europe PMC, 2023 - Hemopoietic stem cell transplantation in thalassemia: a report from the European Society for Blood and Bone Marrow Transplantation Hemoglobinopathy Registry, 2000-2010
Bone Marrow Transplantation (Baronciani and colleagues), abstract via Europe PMC, 2016 - Transfusion-dependent thalassemias: HCT consultation timing guidelines and outcomes
NMDP, Accessed 2026-09-26 - Alpha thalassemia
MedlinePlus Genetics, US National Library of Medicine, Last updated 2022-12-02; accessed 2026-09-26
This information explains a condition and its treatments. It cannot diagnose an illness or recommend treatment for an individual. Your care team can explain how the evidence applies to you. Written and source-checked by the Jada Bascom Foundation. Each page lists the published sources it draws on.
Ways to help
Other patients are waiting for a match.
People with beta thalassemia major (transfusion-dependent) may be treated with a transplant or, in some countries, a gene therapy. Many people with other blood cancers and blood disorders need a donor who is a stranger.
Help someone you love find a donor
When a donor transplant is planned, brothers and sisters are usually tested first. Each full sibling has about a one in four chance of being a full match.
Join the registry
When no brother or sister matches, for this condition or another, the search turns to volunteer registries. JBF points you to the official registry that serves your country.
Support this work
Gifts to the Jada Bascom Foundation support donor-awareness education like this page, community outreach, drive planning and referrals to official registries.
More in the library
Keep learning
Part of Thalassemia, a guide to how the subtypes fit together.
