Thalassaemia is the name given to a group of inherited blood disorders that affect the body’s ability to create red blood cells.
Red blood cells
Red blood cells are very important because they carry a protein called haemoglobin around the body. Haemoglobin transports 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 our body takes from food.
In cases of thalassaemia, the bone does not produce haemoglobin, causing anaemia and reduced oxygen-carrying capacity. If your body does not receive enough oxygen, you will feel tired, breathless, drowsy and faint. 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 chain is produced by four genes, two on each chromosome 16, and the severity of the condition depends on how many of those genes have been mutated.
- If one gene is mutated, there is little or no effect.
- If two genes are mutated, there may be symptoms of mild anaemia. This condition is known as the alpha thalassaemia trait. If two people with the alpha thalassaemia trait have a child, there is a one-in-four chance the child will inherit the most severe form of alpha thalassaemia (see below).
- If three genes are mutated, the result will be a condition called haemoglobin H disease. People with haemoglobin H disease 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.
Beta thalassaemia can range from moderate to severe. The most severe form of the condition is known as beta thalassaemia major (BTM). People with BTM will require blood transfusions for the rest of their life.
The milder form of the condition is known as beta thalassaemia intermedia (BTI), also referred to as non-transfusion dependent thalassaemia (NTDT). The symptoms of BTI will vary from person to person. Some will experience symptoms of mild anaemia while others will require blood transfusions.
Read more information about the symptoms of thalassaemia.
This article will focus mainly on BTM because it is the most common and severe form of the condition in the UK.
Alpha thalassaemia is also found in the UK, particularly among people of South Asian, Southeast Asian and Mediterranean descent, and also amongst Africans. In Africans it is typically the mildest form of the condition. People of Southeast Asian and Mediterranean descent are at risk of producing alpha thalassaemia major (ATM) due to their more severe form of alpha thalassaemia.
Read more information about the causes of thalassaemia.
Who is affected
It is estimated there are 1,000 people in the UK living with BTM and most cases are found in people of Mediterranean, Middle Eastern and, in particular, South Asian ancestry. Eight out of 10 babies born with BTM in the UK have parents of Indian, Pakistani or Bangladeshi ancestry.
Pregnant woman are checked for inherited disorders during routine antenatal screening. Thalassaemia is also diagnosed using a blood test although further tests may be needed to tell which type it is.
Read more information about how thalassaemia is diagnosed.
The only known cures for thalassaemia are a bone marrow transplant and cord blood transplantations (using blood cells taken from an unborn baby carried by a mother who also has an older affected child). These procedures can cause other complications and are not suitable for everyone.
One of the biggest problems with BTM is that it requires frequent blood transfusions, which in turn can lead to a build-up of iron in the body. This can cause serious health problems.
People who receive regular blood transfusions for BTM must undergo treatment called chelation therapy to remove the excess iron from their body.
Read information about how thalassaemia is treated.
It can be challenging to live with BTM as frequent check-ups are needed to assess the risk of possible complications. Complications of thalassaemia can include:
- an enlarged spleen (hypersplenism) - 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 (a condition where the bones become thin and brittle)