Genetics services

Genetic testing can be used to find out whether a person is carrying aspecific genetic mutation (altered gene) that causes a particular medical condition.

Itmay be carried out for anumber of reasons, including:

You will usually need to get a referral from your GP, or a specialist doctor if you have one, for genetic testing to be carried out speak to your GP or your doctor about the possibility of testing if you think you may need it.

Genetic testing usually involves having a sample of your blood or tissue taken. The sample will contain cells containing your DNA and can be tested to find out whether you are carrying a particular mutation and are at risk of developing a particular genetic condition.

In some cases, genetic testing can be carried out to see if a foetus is likely to be born with a certain genetic condition by testing samples of amniotic fluid (the fluid that surrounds the foetus in the womb) or chorionic villi cells (cells that develop into the placenta) extracted from the mother's womb using a needle.

Depending on the condition(s) being tested for, the blood or cell samples will then be tested and examined in a genetics laboratory to check fora specific gene, a certain mutation on a specific gene or any mutation on aspecific gene.

In some cases, it may be necessary to check an entire gene for mutations, using a process called gene sequencing. This has to be done very carefully, and it can take a long time compared to most other hospital laboratory tests.

Depending on the specific mutation being tested for, it can take weeks or even months for the results of genetic tests to become available. This can be because the laboratory has to gather information to help them interpret what has been found.

It is also important to realise that it is not always possible to give definite answers after genetic testing. Sometimes it is necessary to wait to see if the person being tested or other relatives do, or do not develop a condition, and other tests may need to be performed.

You can find out more about genetic testing and how it is carried out by reading the leaflet: 'What happens in a genetics laboratory?' (PDF, 1.90Mb).

If your doctor thinks genetic testing may be appropriate in your case, you will usually be referred for genetic counselling as well.

Genetic counselling is a service that provides support, information and advice about genetic conditions. It is conducted by healthcare professionals who have been specially trained in the science of human genetics (a genetic counsellor or a clinical geneticist).

What happens during genetic counselling will depend on exactly why you've been referred. It may involve:

You will be given clear, accurate information so you can decide what's best for you.

Your appointment will usually take place at your nearest NHS regional genetics centre. The British Society for Genetic Medicine has details for each of the genetics centres in the UK.

For couples at risk of having a child with a serious genetic condition, pre-implantation genetic diagnosis (PGD) may be an option.

PGD involves using in-vitro fertilisation (IVF), where eggs are removed from a woman's ovaries before being fertilised with sperm in a laboratory. After a few days, the resulting embryos can be tested fora particular genetic mutation and a maximum of two unaffected embryos are transferred into the uterus.

While PGD has the advantage of avoiding the termination of foetuses affected byserious conditions, it also has a number of drawbacks. These include the modest success rate of achieving a pregnancy after IVF, as well as the substantial financial (PGD is not always available on the NHS) and emotional burdens of the combined IVF and PGD process.

Page last reviewed: 08/08/2014

Next review due: 08/08/2016

Follow this link:
Genetics - Genetic testing and counselling - NHS Choices

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