Types of thalassaemia
People originating from the Mediterranean, the Middle East, Africa or Asia may carry some form of thalassaemia but it’s rare in Northern Europeans.
Thalassaemia is common in these regions because it helps to protect carriers against malaria.
Thalassaemia is a characteristic of the blood. It is inherited, that is, it is passed on from parents to children, like hair, eye or skin colour. It is passed on equally by men and women. It is not catching and will not turn into an illness.
Beta thalassaemia carriers are healthy and do not know that they are carriers unless they have a special blood test carried out. This blood test can be done by your GP and the result should be known within two weeks. The difference between a carrier and a non-carrier is that the red cells of the carrier are slightly smaller than those of the non-carrier. This is sometimes mistaken for iron deficiency anaemia and iron is prescribed. Thalassaemia carriers should not take iron unless they need it. The iron level in the blood must be measured to see if iron intake is really needed.
There are two forms of thalassaemia: alpha thalassaemia and beta thalassaemia.
ALPHA THALASSAEMIA CARRIER
Carrying alpha thalassaemia does not cause any illness. Most people who carry alpha thalassaemia do not know they have it. They only discover it when they have a special blood test. However, it can cause confusion and in some cases it could affect the health of your children.
There are two types of alpha thalassaemia; alpha plus thalassaemia, which is harmless and alpha zero thalassaemia which may have more serious implications.
BETA THALASSAEMIA CARRIER – (BETA THAL MINOR OR BETA THAL TRAIT)
Carriers of beta thalassaemia are normally healthy and will not know that they are carriers unless they have a special blood test to detect this condition. Although being a beta thalassaemia carrier does not cause any symptoms it’s important for them and for their doctors to know if they have this condition for various reasons.
The size and colour of their red cells maybe slightly different from people without this condition. If a person is a carrier of beta thalassaemia and has a blood test for some other reason the fact that they carry beta thalassaemia is not known, it may be confused with other conditions and lead to unnecessary tests and/or treatment.
Before a person who is a carrier of beta thalassaemia decides to have children it’s advisable for them to find out as soon as possible if their partner is also a carrier of beta thalassaemia or another interacting haemoglobin such as sickle haemoglobin (Hb S), Hb O Arab or Hb Lepore. This only requires a simple blood test. This test is advisable because, if positive, there will be a 1 in 4 chance (25%) that any child they have will inherit beta thalassaemia from both parents. If a child inherits beta thalassaemia from both parents it will have Beta Thalassaemia Major and is usually associated with considerable medical problems.
SOME COMMON VARIATIONS
If a child inherits beta thalassaemia from one parent and Hb E, Hb O Arab or Hb Lepore from the other parent, then the child will have a type of thalassaemia. If this happens the child may develop medical problems associated with beta thalassaemia intermedia or beta thalassaemia major.
If a child inherits beta thalassaemia from one parent and sickle cell from the other parent, then the child will have a type of sickle cell disease called “sickle beta thalassaemia”. If this happens the child may develop medical problems associated with sickle haemoglobin.
If your child is a carrier of beta thalassaemia it’s advisable for you as parents to find out your haemoglobin types to determine if there is any risk of serious haemoglobinopathy in future pregnancies. It’s also advisable to test any other children in your family.