Your antenatal blood test result: you are a beta thalassaemia carrier
You should read this information if the result of your antenatal screening blood test for sickle cell and thalassemia (SCT) shows you are a beta thalassemia carrier. Some people call this ‘having a trait’. This leaflet gives you information about being a carrier, and what this means for you and your family.
Published January 2022
Contents
― Being a carrier
― Your baby
― Chances of inheriting a serious condition
― Thalassaemia major
― Sickle cell disorder
― Next steps and choices
― Newborn Screening
― Other family members
― Future pregnancies
― How your test result is written
― More information
Being a carrier
Being a carrier does not make you ill. You will not develop a thalassaemia condition that needs treatment, but it is important to know that you can pass the beta thalassaemia gene on to your baby. If your baby’s biological father is also a carrier, together you could have a baby with a serious inherited condition. The chance is the same in every pregnancy.
Haemoglobin is the substance in red blood cells that carries oxygen around your body. Being a carrier means you have inherited one usual haemoglobin gene called haemoglobin A from one biological parent and one beta thalassaemia gene from your other biological parent. Because you have inherited usual haemoglobin A from one parent, you are healthy.
If your baby’s biological father has an unusual haemoglobin gene it is important to identify the type of gene and the chance of your baby inheriting a serious haemoglobin condition. For this reason, we will also invite the biological father for screening. He will only know if he carries a gene for unusual haemoglobin if he has a blood test to check his haemoglobin type.
If the test shows your baby’s biological father is a carrier of an unusual haemoglobin gene you will be offered specialist counselling and, if necessary, invasive testing.
Please let your healthcare professional know if you:
- became pregnant as a result of fertility treatment with donor sperm or a donor egg;
- have had a bone marrow or stem cell transplant; or
- are pregnant as a surrogate.
As a beta thalassaemia carrier your red blood cells are smaller than usual and your haemoglobin level is lower than normal. This is different to iron deficiency anaemia. Before taking iron supplements always ask your healthcare professional to check your iron levels.
Your baby
There are a number of different haemoglobin conditions your baby could inherit. Some are more serious than others. The type and severity of the condition depends on the types of haemoglobin genes you and your baby’s biological father have.
The most serious conditions are thalassaemia major and sickle cell disorder. People who have thalassaemia major or sickle cell disorder need specialist care and treatment throughout their lives.
Chances of inheriting a serious condition
One biological parent is a carrier and the other is not
If your baby’s biological father has two usual haemoglobin genes (AA), there is a 2 in 4 (50%) chance your baby will be a beta thalassaemia carrier (like you) and a 2 in 4 (50%) chance they will have two usual haemoglobin genes (AA).
See diagram below. These chances are the same in every pregnancy for this couple.
Both biological parents are carriers
If your baby’s biological father is also a carrier, there is a 1 in 4 (25%) chance your baby will inherit a haemoglobin condition. The seriousness of the condition will depend on what haemoglobin genes are inherited.
There is also a 2 in 4 (50%) chance your baby will be a carrier, and a 1 in 4 (25%) chance your baby will have usual haemoglobin genes (AA).
See diagram below. These chances are the same in every pregnancy for this couple.
Thalassaemia major
People with thalassaemia major:
- are very anaemic (their blood has difficulty carrying oxygen);
- usually need blood transfusions every month; and
- need medicines (iron chelation therapy) to stop the iron overload which is a result of the monthly blood transfusions.
Sickle cell disorder
People with sickle cell disorder have red blood cells that can become misshapen when they release oxygen around the body. This can block small blood vessels.
People with sickle cell disorder:
- can have attacks of very severe pain;
- can get serious, life-threatening infections;
- are usually anaemic; and
- need medicines and injections when they are children and throughout the rest of their lives to prevent infections.
Next steps and choices
If screening shows your baby could inherit a serious haemoglobin condition you will be offered specialist counselling and invasive testing.
Newborn screening
All babies are offered a newborn blood spot screening test five days after their birth. This test will screen for sickle cell disorder.
You can also:
- let your GP or healthcare professional know you are a beta thalassaemia carrier;
- contact a specialist sickle cell thalassaemia centre where you can get free information and advice to help you understand the implications of being a beta thalassaemia carrier; and
- organise for any other children you have to be tested if needed, with help from your GP or sickle cell thalassaemia centre.
Other family members
As you are a beta thalassaemia carrier, other members of your biological family could be carriers too.
We recommend you talk to your parents, brothers, sisters, uncles, aunts and cousins, and encourage them to get a test before they start a family or have any more children. Showing them this information may help.
It is equally important for men and women to be tested. Anyone can ask for a test at any time from their GP or from a specialist sickle cell thalassaemia centre.
Future pregnancies
We recommend you tell your healthcare professional about your carrier status as early as possible in any future pregnancies.
It is important to test the biological father and be referred to a specialist counsellor.
How your test result is written
As a beta thalassaemia carrier your screening test result is written Aβ thalassaemia.
The letter A represents your usual haemoglobin A gene. The Greek letter β is beta.
More information
You can get more information from the following.
https://111.wales.nhs.uk/encyclopaedia/t/article/thalassaemia/