Thalassaemia

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 red spongy material found inside the larger bones) using the iron that our body takes from food.

If your body does not receive enough oxygen, you will feel tired, breathless, drowsy and faint. This condition is known as anaemia. 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 both an alpha chain and a beta chain of proteins.

A mutation that affects the alpha chain causes alpha thalassaemia, and a mutation that affects the beta chain causes beta thalassaemia.

Alpha thalassaemia

The alpha chain is produced by four genes 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 that their 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

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 more moderate form of the condition is known as beta thalassaemia intermediate (BTI). The symptoms of BTI will vary from person to person. Some will experience only symptoms of mild anaemia while others will require blood transfusions.

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.

This article will focus mainly on BTM because it is the most common and severe form of the condition in the UK. While alpha thalassaemia can be found in the UK, particularly among people of South Asian and Southeast Asian descent, it is typically the mildest form of the condition.

How common is BTM?

BTM is an uncommon disorder. It is estimated that 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.

Outlook

BTM can be challenging to live with, but the outlook for the condition is moderately good.

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.

In the past, almost all children with BTM would die before the age of 18 due to a build-up of iron in their heart.

The outlook improved dramatically during the 1960s, as new medications and treatments that helped remove iron from the body became available. These types of treatment are known as chelation therapy. An increasing number of people with BTM now live into old age.