What is Thalassaemia?
Thalassaemia is a group of inherited blood disorders
where the haemoglobin in the blood 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
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.
Unlike alpha genes, there are only two beta genes, one each on
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
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.
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
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.
What causes thalassaemia?
Thalassaemia is an inherited condition, which means it can be
passed on to you from your nts. 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 or has been a problem, including the
Middle East, Asia, sub-Saharan Africa and certain Mediterranean
countries such as Greece, Cyprus and Italy.
Thalassaemia can be diagnosed using a blood test. DNA tests
may also be needed to determine the exact type of thalassaemia. All
pregnant women are offered screening
for thalassaemia as part of their antenatal
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.