Beta Thalassaemia Trait
What does it mean to carry beta thalassaemia?
Beta thalassaemia is a haemoglobin disorder. Many people of “not Northern European origin” carry beta thalassaemia (Cypriots 16%, S. Europeans 3.8%, South East Asian (e.g. Hong Kong Chinese) 8%, Pakistanis 4.5%, Middle East and India 3.5% or more. African Caribbeans 1.2%, black Africans 1%). 0.1-0.2% of Northern Europeans are carriers.
Haemoglobin disorders are recessively-inherited. People who carry one beta thalassaemia gene (heterozygotes) are popularly said to carry beta thalassaemia, or have beta thalassaemia trait. The diagnosis of typical beta thalassaemia trait is based on microcytosis (low MCV<80fl and MCH<27pg ) and a raised Hb A2 (more than 3.5%).
People who carry beta thalassaemia inherited it from one of their parents, and may pass it to their children. They will always carry it. It will not develop into a serious anaemia.
Can beta thalassaemia cause any health problems for carriers?
Some carriers have a mild anaemia, but the majority have a Haemoglobin level in the normal range. Carriers are no more likely to become ill than other people, and can do any kind of work.
The most important health problem for carriers is the risk of iatrogenic iron overload. Microcytosis and mild anaemia can lead to an erroneous diagnosis of iron deficiency anaemia, and years of unnecessary iron medicines. A serum ferritin measurement is necessary to make a diagnosis of iron deficiency in a thalassaemia carrier.
Carriers are as likely to become iron deficient as anyone else, particularly during pregnancy, when iron supplements may be needed.
Why is it important to know you carry beta thalassaemia?
Though carrying beta thalassaemia does not affect their own health, carriers risk having a child with a serious haemoglobin disorder. This can happen only if their partner is also a carrier. It is important to know about this risk, because it can be avoided.
If your patient has a partner and is thinking of having children, it is important for your patient to tell their partner about beta thalassaemia, and ask him or her to have a blood test for haemoglobinopathy 4mls EDTA (0.3-1ml for infants for haemoglobinopathy screen is all that is required).
If this test shows the partner is not a carrier, there is no risk of having a child with a serious haemoglobin disorder. If the test shows the partner is a carrier, the couple should be referred to a specialist thalassaemia counsellor, to discuss their reproductive options, including prenatal diagnosis.
Is there anything else your patient should do now?
If your patient has brothers or sisters or children, they may also carry beta thalassaemia. They should be offered a blood test.
