A Guide to Understanding Beta Thalassemia

Beta thalassemia is an inherited blood condition in which the body makes too little of one building block of hemoglobin, the protein that carries oxygen, so red blood cells cannot do their job properly [1].

This page provides general information. It does not replace advice from a doctor or another qualified healthcare professional.

Key facts

Beta thalassemia is caused by changes in a gene called HBB, which reduce or stop production of beta globin, one of the parts of hemoglobin [1].
It is usually inherited from both parents. A person with one changed copy is a carrier, often called having thalassemia trait or minor, and is usually healthy [1,3].
Care teams now group it by how much treatment a person needs, transfusion dependent or non-transfusion dependent, rather than by the older labels major, intermedia and minor [2].
It is most common in families from the Mediterranean, the Middle East, Central and Southeast Asia and the Indian subcontinent, and migration means it now occurs almost everywhere [2,7].
The main long-term problem in people who are treated is too much iron in the body, caused by the transfusions themselves, which is why iron-removing medicine is part of care [2,3].
Stem cell transplant is the established curative option, and two gene therapies have now been approved by regulators, though availability, cost and access differ sharply between countries [2,13,14].

What is beta thalassemia?

Beta thalassemia is an inherited blood condition in which the body makes too little of one part of hemoglobin [1].

Hemoglobin is the protein inside red blood cells that picks up oxygen in the lungs and carries it around the body. It is built from four pieces: two called alpha globin and two called beta globin [1]. In beta thalassemia, changes in a gene called HBB reduce or completely stop production of beta globin [1]. Without enough of it, red blood cells are small, pale, short-lived and too few, so less oxygen reaches the body. That shortage of healthy red blood cells is called anemia [1,4].

Care teams now group beta thalassemia by how much treatment a person needs: transfusion dependent, where regular blood transfusions are needed to survive, and non-transfusion dependent, where they are not [2]. Older names are still widely used: beta thalassemia major, or Cooley’s anemia, is transfusion dependent by definition; intermedia usually is not; minor, also called thalassemia trait, is the carrier state [2]. Alpha thalassemia is a separate group affecting alpha globin [4].

How common is it?

An analysis of global health data published in 2024 estimated that about 1,310,000 people were living with thalassemia of all types in 2021, and about 119,700 were born with it that year [11]. Those figures cover alpha as well as beta thalassemia, and a 2025 review concluded that the true burden cannot be measured reliably, since most countries keep no national records [12].

Being a carrier is far more common than having the condition. Carrier rates reach about 18 percent in the Maldives, 14 percent in Cyprus and 10.3 percent in Sardinia, and 3 to 5 percent across Southeast Asia [7]. Beta thalassemia is most frequent in people whose families come from the Mediterranean, the Middle East, Central and Southeast Asia and the Indian subcontinent, and is also common in people of African descent [2]. That map follows the historical map of falciparum malaria, and one changed copy is thought to have offered some protection against it. Migration means it now occurs almost everywhere [2,7].

What causes it?

Genes are the instructions inside our cells, and beta thalassemia is caused by changes in the HBB gene, which carries the instructions for beta globin; around 200 different changes are known [1,5].

It is usually inherited in a pattern called autosomal recessive: everyone has two copies of HBB, one from each parent, and someone with one changed copy and one working copy is a carrier, often described as having thalassemia trait or minor [1,3]. Carriers are usually healthy and do not develop thalassemia, though some have smaller red blood cells and mild anemia, which is not iron deficiency and needs no treatment [3].

A child develops beta thalassemia only when both copies are changed, so where both parents are carriers, in each pregnancy there is a 1 in 4 chance the child will have the condition, a 1 in 2 chance of being a carrier and a 1 in 4 chance of inheriting neither changed copy, and those chances are the same in every pregnancy [2,3]. Such couples can ask for genetic counseling, which sets out the local options rather than recommending a decision [16]. Rarely, one changed copy is enough to cause symptoms, called dominant beta thalassemia [1,2].

What are the symptoms?

Symptoms depend on how much beta globin the body can make. Carriers usually have none, or mild anemia found on a blood test done for another reason [1,3].

Children with the severe form usually come to medical attention between 6 and 24 months of age, with paleness from severe anemia, poor weight gain, slow growth and an enlarged spleen and liver [2]. Where regular transfusions are not available, the bone marrow expands as it tries to make more red blood cells, reshaping and weakening bones, changing the face and skull and delaying puberty [1,2,4]. Without transfusions people usually die within the first two decades of life; where treatment starts before age two, children grow and develop normally into their early teens [2].

Milder forms may not appear until later childhood or adulthood, with tiredness, breathlessness, palpitations, pale skin, gallstones and leg ulcers [2,3,4].

When to seek urgent help. Contact the care team the same day for a high fever, since an enlarged or removed spleen makes serious infection more likely [2,4]. Call emergency services for sudden chest pain, severe breathlessness or fainting; for pain and swelling in one leg, since blood clots are more likely; and for sudden back pain with weakness in the legs, since masses of blood-forming tissue can press on the spinal cord [2].

How is it diagnosed?

Beta thalassemia is found through screening in pregnancy, newborn screening, or when a child becomes unwell in the first two years of life [2,3,24].

In England, all pregnant women are offered screening for thalassemia, ideally before 10 weeks and 6 days, and the baby’s biological father is offered testing if she is a carrier [24,25]. All newborn babies are offered a heel prick blood test at about five days old [3,24].

The first test is a full blood count, which shows small, pale red blood cells [2]. Hemoglobin analysis follows, by electrophoresis or high performance liquid chromatography, usually shortened to HPLC. A raised level of hemoglobin A2 points to beta thalassemia, and the usual adult hemoglobin is reduced or absent [2]. Genetic testing of HBB confirms the diagnosis, and is needed in babies under 12 months, where the milder pattern can look normal [2].

How is it treated?

Treatment depends on the form a person has [2,3].

Regular blood transfusions. People with the transfusion-dependent form receive donated red blood cells into a vein every two to five weeks, with guidelines recommending hemoglobin of 9.5 to 10.5 grams per deciliter beforehand [8,14]. This corrects the anemia and calms the overworked bone marrow [2,8].

Too much iron, caused by the treatment itself. Every unit of blood carries iron with it, and the body has no way of removing extra iron, so it builds up in the heart, liver and hormone glands and damages them. Iron overload, not the anemia, is the main long-term problem in treated beta thalassemia [1,2,3].

Iron chelation and iron scans. Chelation means taking a medicine that grabs hold of iron so the body can remove it. Three are licensed: deferoxamine, also called desferrioxamine, given by slow infusion under the skin, and deferiprone and deferasirox, taken by mouth [9]. It only works if taken regularly, which guidelines call the central problem [9]. Yearly MRI scans of the liver and heart from around age 8 to 10 measure iron without a biopsy, and with better chelation they are the main reason deaths from cardiac iron fell [2,9].

Medicines that reduce the need for transfusion. Luspatercept, an injection under the skin every three weeks, helps red blood cells mature. The European Union approves it for adults with either form [18], the United States for adults who need regular transfusions [19]. It reduces transfusion needs for a minority of people rather than everyone [2].

Stem cell transplant. Stem cells from a donor replace a person’s own after strong chemotherapy. This is the established curative option, and results are best in children without existing liver or iron damage [2].

Gene therapy and gene editing. Two treatments change a person’s own stem cells instead of a donor’s: betibeglogene autotemcel adds a working beta globin gene, and exagamglogene autotemcel uses CRISPR gene editing to switch fetal hemoglobin back on [14,15]. Both need stem cells collected, altered in a laboratory and returned after strong chemotherapy, which can permanently affect fertility [14,23]. At least 90 percent of people treated with either have stopped transfusions [14]. Betibeglogene autotemcel is approved in the United States; its European authorization was withdrawn in 2022 at the manufacturer’s request for commercial reasons [20,21]. Exagamglogene autotemcel is approved in both the United States and Europe [22,23]. Upfront costs run into the millions, and researchers caution that calling these a cure oversimplifies things [14].

Availability is unequal, and that is a fact about health systems. More than 80 percent of people with the condition live in countries with limited resources, where transfusion, chelation and transplant are hardest to obtain, and the Thalassaemia International Federation estimates that fewer than 10 percent worldwide can benefit from recent advances [6,13]. In high-resource settings more than half live to age 60; in low-resource settings more than half die before age 30 [2].

Living with beta thalassemia

Care works best through a specialist center where several professions work together [10]. Hepatitis B vaccination is given before transfusions begin, and iron supplements avoided unless a doctor advises otherwise [2]. Thin bones are common in adults, so vitamin D, activity and good control of anemia and iron all help. Hormone and heart checks are done yearly from childhood [2].

Fertility is often preserved. Puberty is frequently delayed, yet the ovaries and testes usually work and assisted reproduction is often successful [2]. Pregnancy usually goes well when planned in advance with a multidisciplinary team, and since iron chelation cannot be used in the first three months, getting iron under control beforehand is ideal [2]. Moving from children’s to adult services needs careful handover, so specialist contact is not lost [10].

Thinking about a clinical trial?

Clinical trials are research studies that test whether a treatment works and is safe. Beta thalassemia is an active research area, so studies come up from time to time. Deciding whether to look into one is personal, and it helps to take it in steps.

1. Understand what the study is asking

It is worth being clear on what a study actually involves:

what the researchers are trying to learn
what treatment is being studied, and what it is being compared with
how long it lasts, which for gene therapy studies can be many years
what visits, tests, scans or procedures are involved, how often, and how far you would travel
the possible benefits, and the known and unknown risks
what happens at the end, including who provides treatment afterward

2. Consider possible medical suitability

Every trial has rules about who can take part. These are called eligibility criteria. Some describe who can join, and others who cannot. For a beta thalassemia study they might include a confirmed diagnosis with the exact HBB gene changes identified, whether a person is transfusion dependent, the units of blood received in the past year or two, an age range, hemoglobin level, iron levels in the liver and heart, the current chelation medicine, liver and kidney health, and any earlier transplant or gene therapy.

trialport’s medifit helps people consider information related to possible medical suitability. It does not diagnose a condition, confirm eligibility or replace formal screening by the study team.

Explore beta thalassemia clinical trials through trialport

3. Consider whether participation fits your life

Medical suitability is only part of the picture. A study can look right on paper and still be hard in practice:

the time each visit takes, how many there are, and who would come with you
work, school or caring responsibilities, and whether time off is possible
how you feel about extra blood tests, scans or hospital stays
for studies involving chemotherapy, a long stay in hospital and effects on fertility
whether a long follow-up period fits your plans
the support you have around you, and for parents, how a child feels about it

trialport’s readifit helps people reflect on their understanding, motivation, time, routines, support, emotions and practical arrangements.

4. Ask questions before deciding

Useful questions to put to a research team:

Why is this study being carried out, and what exactly would I need to do?
What are the known risks, and what is still unknown?
Could I receive a placebo? A placebo is a dummy treatment with no active medicine, used so that researchers can compare results fairly.
Would I keep my usual transfusions and chelation while taking part?
Could this affect my fertility, and what can be done about that beforehand?
How would you monitor me, and what if the treatment did not work?
Can I leave after joining, and are travel costs covered?
What happens when the study ends, and would I still get the treatment?

Taking part is voluntary. A person can ask questions, speak with people they trust and choose not to participate.

Search for clinical trials at app.trialport.com.

Current research

Research covers several areas:

Switching fetal hemoglobin back on. Babies make a different form of hemoglobin before birth, and restarting it makes up for missing beta globin. Approved gene editing works this way, and other editing approaches are under study [15,17].
Gene therapy that is easier to give. Gentler conditioning, and editing genes inside the body, would remove the need to collect stem cells [14].
Medicines acting on iron signaling. Agents aimed at hepcidin, erythroferrone, TMPRSS6 and ferroportin are being tested [15].
Fairer access. Professional bodies have set out how to prioritize newer treatments where resources are short [13].

Study status checked: 3 August 2026. Research moves and what is being studied changes, so this list will date. For current information, search at app.trialport.com.

Support and further information

Internationally, the Thalassaemia International Federation publishes the main treatment guidelines, in free full text, and works with member associations in many countries [6,27]. In the United States, the Cooley’s Anemia Foundation has supported families for more than 70 years and funds research [26]. In the United Kingdom, the UK Thalassaemia Society is the national charity and holds an NHS screening contract [25]. The NHS guide covers carrier testing [3], and the CDC pages are a clear US starting point [4]. Organized support is thinner across much of Africa and South America, where access to treatment is also hardest [13].

Well-known people with beta thalassemia

Pete Sampras, the American tennis player and 14-time Grand Slam singles champion, has said publicly that he and other members of his family have thalassemia minor, and that it never affected him on court [28]. A commentary in the journal Blood names him and describes reduced beta globin production, the carrier form [29].

No widely known public figure appears to have publicly confirmed a transfusion-dependent form.

Questions people often ask

I am a carrier. Will I become ill?
Almost certainly not. Carriers do not develop thalassemia and are generally healthy. Some have mild anemia and smaller red blood cells, which needs no treatment [3].

If both parents are carriers, will every child be affected?
No. In each pregnancy there is a 1 in 4 chance the child will have the condition, a 1 in 2 chance of being a carrier and a 1 in 4 chance of neither. The odds reset with every pregnancy [2,3].

Should I take iron tablets if I am tired and anemic?
Not without advice. This anemia is not caused by a shortage of iron, and people with the condition are advised to avoid iron supplements unless a doctor says otherwise [2,3].

Why does treatment cause too much iron?
Each transfusion brings iron in, and the body cannot remove the excess. It settles in the heart, liver and hormone glands, which is why iron-removing medicine and yearly MRI scans are part of care [1,2,9].

Is there a cure?
Stem cell transplant from a matched donor can cure it, and two gene therapies are approved by regulators. All involve strong chemotherapy and real risks, and researchers point out that the word cure oversimplifies what is known [2,13,14].

Is beta thalassemia the same as sickle cell disease?
No, though both affect hemoglobin and both are inherited. Sickle cell disease changes the shape of hemoglobin, while beta thalassemia reduces how much is made. Screening programs often test for both together [1,24].

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Review information

Written by: trialport editorial team
Reviewed by: Keith Berelowitz, Founder and CEO, trialport
Reviewed on: 3 August 2026
Next review due: 3 August 2027
References last checked: 3 August 2026

Beta thalassemia: a plain-language guide