Thalassaemia is a group of inherited blood disorders where the part of the blood known as haemoglobin is abnormal.
The abnormality means that the affected red blood cells are unable to function normally, which leads to anaemia (a red blood cell deficiency).
Red blood cells
Red blood cells are very important because they contain a substance called haemoglobin, which carries oxygen from the lungs to the rest of the body.
Haemoglobin is produced in the bone marrow (a spongy material found inside larger bones) using the iron that the body gets from food.
In thalassaemia, haemoglobin production is abnormal, leading to anaemia and a reduced oxygen-carrying capacity. If your body doesn't receive enough oxygen, you'll feel tired, breathless, drowsy and faint.
If left untreated, the most serious types of thalassaemia can cause other complications, including organ damage, restricted growth, liver disease, heart failure and death.
Types of thalassaemia
Thalassaemia is caused by alterations (mutations) in the genes that make haemoglobin.
Haemoglobin is made up of matching chains of proteins, which are named after Greek letters of the alphabet. To work properly, haemoglobin needs a pair of alpha chain and a pair of beta chain proteins.
A mutation that affects the alpha chain causes alpha thalassaemia, and a mutation that affects the beta chain causes beta thalassaemia.
The alpha chains are produced by four genes, two on each chromosome 16, inherited as pairs. The severity of the condition will depend on how many of those genes have been altered.
If one gene is mutated, there's little or no effect. If two genes are mutated (one on each chromosome), there may be symptoms of mild anaemia. This condition is known as the alpha thalassaemia trait.
If two people with the alpha thalassaemia zero trait (when two genes on the same chromosome are altered) have a child, there's a one in four chance of the child inheriting the most severe form of alpha thalassaemia.
If three genes are mutated, the result will be a condition called haemoglobin H disease. Someone with this condition will have lifelong (chronic) anaemia and may require regular blood transfusions.
If all four genes are mutated, the result will be the most severe form of alpha thalassaemia, known as alpha thalassaemia major. Infants with this condition are unable to produce normal haemoglobin and are unlikely to survive pregnancy. There have been some cases of unborn babies being treated with blood transfusions while still in the womb, but this type of treatment has a low success rate.
Alpha thalassaemia is a blood disorder that occurs worldwide. It's particularly common in Southeast Asia, and also affects people of Mediterranean, North African, Middle Eastern, Indian and Asian origin.
Unlike alpha genes, there are only two beta genes, one each on chromosome 11.
Beta thalassaemia can range from moderate to severe. The most severe form of the condition is known as beta thalassaemia major (BTM), where both beta genes are affected. People with BTM will require blood transfusions for the rest of their life.
Beta thalassaemia intermedia (BTI) is the milder form of the condition, which is also known as non-transfusion-dependent thalassaemia (NTDT).
The symptoms of BTI will vary from person to person. Some people will experience symptoms of mild anaemia, while others will need blood transfusions.
These pages mainly focus on BTM, which is the most common and severe form of the condition in the UK.
What causes thalassaemia?
Thalassaemia is an inherited condition, which means it can be passed on to you from your parents.
It's not known exactly what causes the genetic mutations associated with thalassaemia. However, it's likely they've survived because carriers of the condition (both alpha and beta thalassaemia) are protected against malaria.
This is why thalassaemia and other related genetic blood disorders, such as sickle cell anaemia, are more common in parts of the world where malaria is a problem, including certain Mediterranean countries such as Greece, Cyprus and Italy, the Middle East, Asia and sub-Saharan Africa.
Thalassaemia can be diagnosed using a blood test. DNA tests may also be needed to determine the exact type of thalassaemia.
Pregnant women are routinely asked if they would like to be checked for inherited disorders such as sickle cell anaemia and thalassaemia during routine antenatal screening.
To help diagnosis, a questionnaire about family origin is used as an initial screening tool to assess the risk of thalassaemia.
The only known cures for thalassaemia are a bone marrow transplant and cord blood transplantations, where blood cells are used from the umbilical cord of a newborn baby with parental consent. However, these procedures can cause a range of complications and aren't suitable for everyone.
One of the biggest problems with BTM is that it requires frequent blood transfusions, which can cause a build-up of iron in the body. This can result in serious health problems.
People receiving regular blood transfusions for BTM must also have iron chelation therapy, which is a treatment to remove the excess iron from their body.
Living with BTM
Living with BTM can be challenging. You'll need to have regular check-ups to assess the risk of possible complications.
Complications of thalassaemia can include:
an enlarged spleen – where the spleen has problems recycling red blood cells, making it grow larger
hormone complications – including delayed puberty and restricted growth
heart complications – such as an irregular or disturbed heartbeat (arrhythmia)
liver complications – such as hepatitis (swelling of the liver) or an enlarged liver (fibrosis)
bone complications – such as bone and joint pain and osteoporosis (where the bones become thin and brittle)
One of the symptoms of beta thalassaemia major is a swollen abdomen caused by an enlarged liver or spleen
Who is affected by thalassaemia?
In England, beta thalassaemia major (BTM) is thought to affect around 1,000 people, with an estimated 214,000 carriers.
It most commonly affects people of Cypriot, Indian, Pakistani, Bangladeshi and Chinese origin.
In the UK, 8 out of 10 babies born with BTM have parents of Indian, Pakistani or Bangladeshi ancestry.
Symptoms of thalassaemia
Most babies born with beta thalassaemia won't show symptoms until they're about six months old.
This is because babies begin life with foetal haemoglobin, which is different to normal haemoglobin. Foetal haemoglobin is replaced by normal haemoglobin six months after a baby is born.
Symptoms of beta thalassaemia major (BTM) usually start at around six months of age and include:
growth problems – not putting on weight or growing in height
anaemia – red blood cell deficiency, leading to tiredness, weakness and shortness of breath
jaundice – yellowing of the skin and whites of the eyes
swollen abdomen (tummy) – this is caused by an enlarged liver or spleen
Children with BTM or severe beta thalassaemia intermedia (BTI) may also experience skeletal deformities (unusual bone growth). This is because their body will try to compensate for the lack of haemoglobin by producing more bone marrow.
Further problems can be as a result of a build-up of iron caused by the body absorbing more iron from food in an effort to create more haemoglobin. Excess iron can also build up from having blood transfusions.
Too much iron in the body can cause tissue damage, particularly to the liver and spleen, making the person more vulnerable to infection. Iron can also affect the body's hormonal system, resulting in development during puberty being delayed or not happening at all.
BTM is a serious condition that places an intolerable strain on the body if left untreated. Lifelong blood transfusions will be needed to treat it.
Causes of thalassaemia
It's not known exactly what causes the genetic mutations associated with thalassaemia.
It's likely the mutations have survived because carriers of the condition (both alpha and beta thalassaemia) are protected against malaria.
This is why thalassaemia and other related genetic blood disorders, such as sickle cell anaemia, are more common in parts of the world where malaria is a problem, such as:
countries in the Mediterranean basin, such as Greece, Cyprus and Italy
the Middle East
How beta thalassaemia is inherited
Every person receives two sets of genes, one from their father and one from their mother. If a person receives one set of mutated genes, they're said to have the thalassaemia trait.
If that person has a baby with someone who also has the thalassaemia trait, there's a significant chance that the baby will receive two sets of mutated genes and develop thalassaemia.
The chances of the thalassaemia trait being passed on are described below.
There's a one in four chance that the baby will receive a pair of normal haemoglobin genes.
There's a one in two chance that the baby will receive one normal gene and one mutated gene. In this case, they won't have thalassaemia but they will have the thalassaemia trait.
There's a one in four chance that the baby will receive a pair of mutated genes and have thalassaemia.
If one parent has the thalassaemia trait and the other parent has normal haemoglobin, their baby won't have thalassaemia. However, there's a one in two chance that the baby will receive the thalassaemia trait.
Beta thalassaemia affects the two genes that the body uses to produce the beta chain found in haemoglobin. Haemoglobin needs both an alpha and beta chain to work properly.
If only one gene is mutated, a person will have the beta thalassaemia trait. Most people won't have any symptoms, but some people may have mild anaemia.
Thalassaemia can be diagnosed using a blood test. Further DNA testing may be needed so the exact type of thalassaemia can be determined.
The purpose of antenatal screening (screening carried out during pregnancy) is to check for inherited disorders, such as sickle cell anaemia, and to provide parents with the information they need to make informed decisions.
Pregnant women are routinely screened for the thalassaemia trait. If they test positive, their partner will also be offered the test. If both parents have the thalassaemia trait, there's a one in four chance their baby will have thalassaemia.
Further testing is also available to confirm whether your baby will definitely be born with thalassaemia. There are three methods of testing for this:
chorionic villus sampling – a small sample of placenta (the organ that's attached to the womb lining during pregnancy) is removed and tested
amniocentesis – a small sample of amniotic fluid is taken from inside the womb for testing
foetal blood sampling – under local anaesthetic, a small sample of blood is taken from your baby's umbilical cord or from the umbilical vein as it passes through their liver
Being told that your baby will be born with thalassaemia can be traumatic and upsetting.
You'll be offered counselling to give you and your partner the opportunity to express your feelings and to ask questions about how the diagnosis may affect you.
The counsellor will tell you about the different options available to allow you to make an informed decision about how to proceed with the pregnancy.
Pre-implantation genetic diagnosis
Pre-implantation genetic diagnosis (PGD) is an option for couples who don't want to give birth to a child with thalassaemia but are unwilling to consider terminating a pregnancy.
PGD is similar to in-vitro fertilisation (IVF). IVF is a method of helping infertile couples conceive by surgically removing an egg from the woman's ovaries and fertilising it with the man's sperm in a laboratory.
As with IVF, PGD involves removing eggs from a woman's ovaries, which are fertilised using a sample of sperm taken from her partner. The fertilised embryo can be tested for thalassaemia. If the results are negative, the embryo can then be implanted into the woman's womb.
PGD is a fairly new procedure that's only available at a number of specialist thalassaemia centres. A list of national sickle cell and thalassaemia centres is available on the Brent Sickle Cell & Thalassaemia Centre website.
Unlike the related blood disorder sickle cell anaemia, newborn babies aren't routinely screened for thalassaemia. There are two reasons for this:
blood tests are usually unreliable during the first six months of life
unlike sickle cell anaemia, thalassaemia doesn't present an immediate threat to a baby's life – babies born with sickle cell anaemia have a high risk of developing serious infections and need immediate treatment with antibiotics
If your baby starts to develop the symptoms of thalassaemia as they get older, a diagnosis can be confirmed using a blood test.
Assessing iron levels
If you have beta thalassaemia major, you'll need regular blood transfusions, which will increase the level of iron in your body.
To remove the excess iron, a treatment known as chelation therapy will be used. This will prevent serious complications from excess iron occurring, such as heart or liver disease.
Regular tests to measure your iron levels will be required to monitor the effectiveness of chelation therapy.
Iron levels can be assessed using:
magnetic resonance imaging (MRI) scans
These are outlined below.
Blood tests are an easy way of measuring the amount of iron in your blood. However, they don't indicate how much iron is collecting in certain organs, such as in your brain.
The measurements provided by blood tests can also be distorted by other factors, such as infection.
Blood tests are used to provide a general overview of how well your chelation therapy is working, but they can't be used in isolation.
It's usually recommended that someone with thalassaemia should have a blood test at least every three months.
A magnetic resonance imaging (MRI) scan uses powerful magnetic waves to produce a detailed picture of the inside of your body. MRI scans are able to detect and measure any iron in your organs.
The two organs known to be most vulnerable to the effects of iron are the liver and the heart.
It's usually recommended that you have an MRI scan of your liver at least once a year and an MRI scan of your heart at least once every two years. More frequent scans may be required if high levels of iron are found in your heart and liver.
A liver biopsy uses minor surgery to remove a tiny section of your liver to test it for the presence of iron.
An MRI scan is usually preferred to a liver biopsy because it's more convenient for both the doctor and the person having the scan. However, if a detailed assessment of the level of iron in the body is required, a liver biopsy may be necessary.
Treatment for beta thalassaemia major (BTM) is a lifelong process that requires different specialists to manage the complications of the condition.
If your child is diagnosed with BTM, they'll be referred to a specialist clinic so that they can be fully assessed.
The main treatment for BTM involves having regular blood transfusions to provide the haemoglobin that the body needs. Having regular blood transfusions can also help prevent many of the complications of BTM, such as skeletal deformities.
Most people with BTM will need a blood transfusion every two to four weeks. The transfusion process takes four to six hours and will usually take place in a hospital.
Blood transfusions are very safe because of the rigorous screening methods used for donated blood. However, a problem associated with having regular blood transfusions is that they leave too much iron in the body.
An excess amount of iron left in the body combined with additional iron from food means that people who have blood transfusions for BTM must also have treatment to remove excess iron from their body. This treatment is known as chelation therapy.
Chelation therapy is vital for people with BTM because excess iron damages the body's cells. Left untreated, it can lead to extensive organ damage.
Treatment with iron chelation therapy is usually lifelong, but it's reassessed regularly and may be altered.
Areas of the body that are particularly vulnerable to the effects of iron include:
the heart – excess iron can cause irregular heartbeats (arrhythmias), heart failure (where the heart can't pump enough blood around the body) and, most seriously, cardiac arrest (when the heart stops beating)
the liver – excess iron can cause hardening of the liver (fibrosis) and scarring of the liver (cirrhosis)
the glands that produce the body's hormones – excess iron can cause diabetes and delayed growth and sexual development
Chelation therapy will usually need to begin once your child has received 10 to 20 blood transfusions.
Medications used in chelation therapy are known as chelating agents. There are three chelating agents currently available, each with their own set of advantages and disadvantages. They are:
Desferrioxamine binds to iron molecules in the body and releases them in urine and stools. It's thought to be the most effective chelating agent. However, it takes a long time to work and is inconvenient to administer.
DFO is usually given through a pump that slowly feeds the medicine through a needle into the skin. This is known as an infusion.
As DFO takes a long time to start working, children will often need an infusion that lasts 10 to 12 hours, five to six nights a week. You and your child will be trained to administer the chelation therapy at home.
Taking DFO can be frustrating, particularly for children and teenagers. While such feelings are understandable, it's important to emphasise to your children how important it is to take DFO as directed, because missing doses could increase their risk of developing serious complications.
It's common to develop pain, swelling, itchiness and redness at the site of the injection. A headache and nausea are also common side effects of DFO.
Tell your treatment team if side effects become particularly troublesome or severe. Your child's dose may need to be adjusted or an additional chelating agent may be required.
Deferiprone also binds to iron molecules in the body and releases them in urine.
It's available in tablet or liquid form, so is more convenient to take than DFO. However, DFP isn't as effective as DFO, particularly in preventing liver damage, so it's usually used in combination with DFO. Combining the two chelating agents means children don't have so many infusions each week (usually two a week as opposed to five or six).
Another disadvantage of DFP is that it causes a wider range of potential side effects, some of which can be serious. Common side effects include:
Agranulocytosis is potentially the most serious side effect of DFP. It's a condition where bone marrow no longer produces enough white blood cells. The body uses white blood cells to protect against infection, so agranulocytosis makes you extremely vulnerable to serious infection.
Most episodes of agranulocytosis occur during the first year of taking DFO, although episodes have been reported after many years of treatment. It's therefore important to look out for any sign of a possible infection, such as:
a high temperature of 38°C (100.4°F) or above
muscle and joint pain
shortness of breath
If you develop symptoms that suggest you may have an infection, stop taking DFP immediately and contact your treatment team for advice. Extra blood tests will be recommended to check the white blood count more frequently.
Deferasirox is a relatively new type of chelating agent that was licensed for use in the UK in 2006.
There's only a limited amount of evidence regarding how effective or safe the medication may be in the long term, but it appears to work as well as DFO in some people.
However, using DFX as an alternative to DFO isn't usually recommended in people with high levels of iron in their heart.
DFX is available in tablet form. Common side effects include:
These side effects are often mild to moderate and usually resolve once your body gets used to the medication.
There have been reports of people developing liver failure when taking DFX, with some cases resulting in death.
However, most of these people already had a history of liver disease or another serious illness. As a precaution, you'll be given regular liver function tests when taking DFX so that the health of your liver can be carefully monitored. Extra kidney tests will also be carried out during treatment.
There have also been reports of people developing stomach ulcers and internal bleeding when taking DFX. As a precaution, look out for symptoms such as:
vomiting blood (the blood can appear bright red or have a darker, grainy appearance similar to coffee granules)
passing dark, tar-like stools (faeces)
a sudden sharp pain in your abdomen (tummy) that gets steadily worse
If you experience any of the symptoms above, stop taking DFX and contact your GP immediately.
Bone marrow transplant
A bone marrow transplant is a possible cure for thalassaemia. It involves replacing affected bone marrow with bone marrow donated from a healthy donor. The new bone marrow will begin to produce healthy blood cells.
There are significant risks involved in having a bone marrow transplant. For example, the new bone marrow can start producing cells that attack parts of your body. This is known as graft versus host disease (GvHD).
GvHD can affect many parts of your body, although the eyes, skin, stomach and intestines are most commonly affected. Symptoms of the condition include:
red spots on the hands, feet and face that spread across the body to form a rash that may later develop into blisters
high temperature (fever) of 38°C (100.4°F) or above
bloody or watery diarrhoea
jaundice (yellowing of the skin and whites of the eyes)
Other risks related to bone marrow transplants include an increased risk of strokes, seizures and tumours.
All families with a child with serious thalassaemia will be given the opportunity to discuss bone marrow transplantation as a possible form of treatment.
There's a greater chance of successfully treating thalassaemia using a bone marrow transplant when:
the child is under 16 years of age – younger children have less organ damage from thalassaemia, so their chances of survival are greater
the child receives the transplanted bone marrow from a brother or sister who shares the same genetic tissue type
All human tissue carries a special genetic marker or code known as a human leukocyte antigen (HLA). As there are several billion possible combinations of HLA, it's extremely unlikely that the right type of bone marrow will be found from somebody who is not related to you.
The survival and success rates for a bone marrow transplant depend on a series of risk factors. The risk factors are:
an enlarged liver
previous poor control of iron levels
The probabilities for successful bone marrow transplant treatment in children under 16 receiving bone marrow from an HLA-matched donor are outlined below.
For children with no risk factors, there's a 95% chance of survival and a 90% chance that treatment will be successful.
For children with one or two risk factors, there's an 86% chance of survival and an 82% chance treatment will be successful.
For children with all three risk factors, there's a 79% chance of survival and a 58% chance treatment will be successful.
Cord blood transfusion
Another possible cure for thalassaemia is cord blood transfusion. This involves testing the HLA tissue type of an unborn baby without thalassaemia being carried by a mother who already has a child with thalassaemia.
If the HLA of the unborn baby matches that of the older brother or sister, it's possible to take a sample of blood from the umbilical cord that can be used at a later date for transfusion.
This blood, known as cord blood, is useful because it's a rich source of stem cells. Stem cells can be used instead of bone marrow because they're capable of producing healthy red blood cells.
The advantage of cord blood transfusions is that there's a lower chance of GvHD occurring and the HLA match doesn't need to be as accurate as that needed for a bone marrow transplant.
As cord blood transfusions are still a relatively new form of treatment for thalassaemia, definitive information about the survival and success rates is limited. However, one small study placed the success rate at 79% and there were no deaths.
If you're a mother of a child with thalassaemia and you conceive another child who doesn't have the condition, staff at your thalassaemia clinic will be able to discuss the possibility of cord donation with you.
Beta thalassaemia intermedia (BTI)
Treatment for beta thalassaemia intermedia (BTI) depends on the severity of the symptoms.
Some people will just require folic acid supplements to help the production of healthy red blood cells.
Others will need occasional blood transfusions and chelation therapy, while those with the most severe symptoms will require a treatment programme similar to the one used for people with beta thalassaemia major (BTM).
If you have BTI, you'll require regular check-ups so the progress of your condition can be monitored and any associated complications can be assessed.
Complications of thalassaemia
One of the most challenging aspects of living with and treating beta thalassaemia major (BTM) is the number of possible complications that can occur.
People with BTM and some people with moderate-to-severe beta thalassaemia intermedia (BTI) will need frequent check-ups so the risk of possible complications can be regularly assessed.
Some common complications of BTM are outlined below.
Enlarged spleen (hypersplenism)
One of the functions of the spleen (an organ found behind the stomach) is to recycle red blood cells. In people with BTM, the blood cells are often abnormal in shape, so the spleen has problems recycling them. The result is that an increasing amount of blood stays in the spleen, making it grow larger.
This can lead to the spleen becoming overactive and starting to destroy healthy blood cells received during blood transfusions, making effective treatment for BTM difficult. In these circumstances, the only treatment is to remove the spleen using a procedure known as a splenectomy.
The spleen also plays an important role in fighting infections. If your child has their spleen removed, it's therefore likely that vaccinations against potentially serious infections, such as meningitis and flu, will be recommended.
Encourage your child to be alert to possible symptoms of infections, such as fever or muscle pain, and report them as soon as possible. This is because infections could have a more serious effect on them than most people.
The pituitary gland is one of the glands that regulates the hormone system. It's very sensitive to the effects of iron and can become damaged in some people with BTM, even if they stick to their chelation therapy.
Pituitary gland damage can lead to a number of hormonal conditions, including delayed puberty and restricted growth. Hormone replacement therapy (HRT) may be needed to treat these conditions.
Other complications that can appear after puberty include diabetes and an underactive thyroid gland or overactive thyroid gland.
Children with BTM will need their height and weight measured every six months to check they're developing normally. Teenagers who've started puberty will need their development assessed every year.
Iron overload can cause damage to the heart, leading to:
an irregular or disturbed heartbeat (arrhythmia)
impaired pumping of the heart (systolic dysfunction)
a build-up of fluid in the tissue of the heart (pleural effusions)
If you have BTM, you'll need a check-up every six months to determine how well your heart is functioning. Every year, you'll also need a full examination carried out by a cardiologist (heart specialist) using an electrocardiogram (ECG) test to measure the electricity of your heart.
If damage to your heart is detected, it can be stopped and possibly reversed using more extensive chelation therapy. Medication such as angiotensin-converting enzyme (ACE) inhibitors can also be used to improve the functioning of your heart.
Iron overload can also cause liver damage, resulting in:
hepatitis (swelling of the liver)
an enlarged liver (fibrosis)
cirrhosis (a progressive condition where the liver is increasingly damaged by scarring)
Chelation therapy can prevent further liver damage and antiviral medicines can be used to prevent further liver infection. Liver tests are recommended every three months to monitor the condition of the liver.
If your body isn't receiving enough healthy red blood cells, it will try to compensate by expanding the bone marrow, which in turn will expand the bones. This can lead to skeletal deformities, bone and joint pain, and osteoporosis (where the bones become thin and brittle.)
Low bone density is common, even in people who've been receiving regular blood transfusions. Those with low bone density are at an increased risk of fracturing (breaking) their bones.
People with BTM are encouraged to eat foods that are rich in calcium and vitamin D, both of which help strengthen the bones. Foods high in calcium include:
dairy products, such as milk and cheese
Foods high in vitamin D include:
You may also be advised to take vitamin D and calcium supplements.
Regular exercise can also help strengthen bones. Adults should do at least 150 minutes (2 hours and 30 minutes) of moderate-intensity aerobic activity, such as cycling or fast walking, every week.
Two types of activity that are particularly important in improving bone density and helping prevent osteoporosis are weight-bearing exercises, such as running and aerobics, and resistance exercises, such as weight training and press-ups.
Osteoporosis can be treated using medicines called bisphosphonates, which help maintain bone density and reduce the chances of fracture. However, bisphosphonates aren't recommended for children and teenagers because they can interfere with normal bone development.