Carrier screening for other reasons
Although most people we talked to had carrier screening during pregnancy, a few discovered they were carriers at other times in their lives. Some people...
Sickle cell and beta thalassaemia are inherited recessive conditions. ‘Recessive’ means a person can only inherit the condition if both parents are carriers. Each child born to a couple who are both carriers has a 1 in 4 risk of having the condition and a 1 in 2 risk of being a carrier. If only one parent is a carrier, their children cannot inherit the condition itself, but they still have a 1 in 2 chance of inheriting carrier status. Being a carrier will not affect the child’s health*.
If a woman discovers during pregnancy that she is a sickle cell or beta thalassaemia carrier, she will usually be advised to tell her partner and suggest he also has a screening test for sickle cell, thalassaemia and other variations (such as haemoglobin C, E, D or O Arab). For many couples, the test will show the male partner is not a carrier, and their baby will not inherit the condition.
There may be a number of reasons why partner screening does not happen. For example some people did not know that white people can carry sickle cell or beta thalassaemia. One woman with a white partner was not advised by staff that he should be screened. She also summarised her views in French.
In some cases, the woman was no longer in contact with the baby’s father, or he was out of the country. One woman’s husband was still in Bangladesh and was not screened. She said she did not really understand the significance of being a carrier until after her son was born with beta thalassaemia major.
Several women found it difficult to persuade their partner to be tested, either because he did not believe it was possible he could be a carrier or because he was anxious about the test, or both. This caused problems in some relationships. One woman who had trouble persuading her partner to have a test later found out that he had known that his nephew had a sickle cell disorder.
People who are fit and healthy often find it difficult to believe they could be a carrier for a condition like sickle cell or thalassaemia. Some men felt sure they were not carriers and told their partners they did not need to be tested.
Women whose partner does not attend for screening can be offered a diagnostic test (CVS or amniocentesis) if they wish to know for certain if the baby is affected.
For women who themselves have a sickle cell disorder or beta thalassaemia major, partner screening becomes even more important. If one parent has the condition and the other is a carrier, each child has a 1 in 2 risk of having the condition. Some women we talked to in this position said they would rather have chosen a partner who was not a carrier, but did not always have the information or services they needed.
Some men may have been tested in another country and been told they were negative. This may be because they have only been checked for HbS (haemoglobin S) and not other haemoglobin variants (such as haemoglobin C, E, D or O Arab) which could still affect the baby if their partner is also a carrier.
This woman and her husband have since been asked to have repeat screening tests several times. They cannot understand why their records do not show they have already been tested.
They both knew that you are either born a carrier or you are not a carrier, and this does not change throughout your life. However, being asked to go back for more tests makes them worry that the first test results might have been wrong.
Another couple were also asked for repeat partner screening because the male partner had changed his name so staff thought she had a new partner, but once it was explained he was in fact the same person there was no problem.
The question of finding out about carrier status before marriage and the implications for relationships is discussed further in ‘Telling people you are a carrier – Implications for relationships and marriage’. The section on newborn tests also contains further experiences of partner screening.
* Although most people who are carriers are generally in good health, there are some possible health effects they need to be aware of. There is a risk to sickle cell carriers of “sickling” under situations of very severe oxygen deprivation. Anaesthetics can cause problems. If you are a sickle cell carrier always notify your dentist or doctor before treatment starts to be on the safe side.
‘There is a small chance that you may experience pain at high altitudes (generally above 10,000 feet), including long-haul flying in unpressurised planes and mountain climbing. It is important you say you have sickle cell trait before undertaking such activities as you may need to breathe oxygen. Extreme exercise may also precipitate problems and if you are a professional athlete you should have a training programme that takes account of this.’ (Sickle Cell Society Dec 2018).
These problems do not apply to carriers of other unusual haemoglobins.
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