Genetic testing can be used to find out whether a person is carrying a specific altered gene (genetic mutation) that causes a particular medical condition.
It may be carried out for a number of reasons, including to:
- diagnose a person with a genetic condition;
- help work out the chances of a person developing a particular condition;
- determine whether a person is a carrier of a certain genetic mutation that could be inherited by any children they have
You’ll usually need a referral from your GP or a specialist doctor for genetic testing to be carried out. Speak to your doctor about the possibility of testing if you think you may need it.
What does genetic testing involve?
Genetic testing usually involves having a sample of your blood or tissue taken. The sample will contain cells containing your DNA. It can be tested to find out whether you’re carrying a certain mutation and are at risk of developing a particular genetic condition.
In some cases, genetic testing can be carried out to find out whether a baby is likely to be born with a certain genetic condition. This is done by testing samples of the fluid that surrounds the foetus in the womb (amniotic fluid) or cells that develop into the placenta (chorionic villi cells), which are extracted from the mother’s womb using a needle.
Depending on the condition(s) being checked for, the fluid or cell samples will be examined and tested in a genetics laboratory to look for a specific gene, a certain mutation on a specific gene, or any mutation on a specific gene.
If your doctor thinks genetic testing may be appropriate for you, you’ll usually be referred for genetic counselling as well.
Genetic counselling is a service that provides support, information and advice about genetic conditions.
It’s conducted by healthcare professionals who’ve received training 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 learning about a health condition that runs in your family, how it’s inherited, and which family members may be affected
An assessment of the risk of you and your partner passing an inherited condition on to your child will be carried out and they will look at the medical history of your family or your partner’s family and draw up a family tree to show you how the genetic fault could be passed onto other members of your family. The Genetic Counsellor should offer to inform any other family members of the risk of them having the condition and explain the need to have testing carried out, however some genetic services expect you to inform other family members. If you are not comfortable or able to do this then you can insist on the counsellor doing this for you.
They will offer support and advice if you have a child affected by an inherited condition and you want to have another child.