Thalassaemia can cause a wide range of health problems, although treatment can help keep many of them under control.
Children born with the main type of thalassaemia, beta thalassaemia major, usually develop symptoms a few months after birth.
Less severe types may not cause any noticeable problems until later in childhood, or even until adulthood.
If you're a carrier of thalassaemia, you'll usually be healthy and will not have any symptoms.
If you have thalassaemia, you may have some of the symptoms discussed on this page.
Almost everyone with thalassaemia major or other serious types will develop anaemia, which can be life threatening in severe cases.
In anaemia there are low levels of haemoglobin, a substance that transports oxygen, in the blood.
It typically causes:
Frequent blood transfusions are usually needed for life to stop anaemia becoming severe.
Most people with thalassaemia major or other severe types will also be at risk of developing a range of health problems caused by a build-up of iron in the body. It's usually a side effect of repeated blood transfusions.
Too much iron in the body can cause:
Lifelong treatment with medicine to stop iron building up to harmful levels will usually be needed. This is known as chelation therapy.
Thalassaemia major or other severe types can also sometimes cause a number of other problems.