What does genetic testing involve?
Genetics testing can be organised by your specialist doctor at a lipid clinic. Genetic testing is not available everywhere in the UK so your specialist will let you know if they think you should have it and if it’s available in your area.
You will need to give a sample of blood or tissue, and the sample will be sent to a laboratory so that your genes can be looked at in detail.
Getting your results
If you are the first person in your family to have a genetics test, it can take time to get your results, for example, around two or three months, or sometimes longer. It’s a complicated test and it can take time to find the gene or parts of the gene involved.
Sometimes a faulty gene can’t be found. Genetic testing can find a faulty gene in about three out of every four people with FH.
If your test finds a faulty gene
If your test finds the gene which is causing your high cholesterol, your specialist will tell you more about what type of FH you have, how it affects your cholesterol level, and the best treatments for you.
They might also ask for your help in finding other close members of your family with FH – this is called cascade testing.
Sometimes a gene alteration will be found but it’s not clear whether it’s harmless or could cause FH. This is called a variant of unknown significance, or VUS. Your specialist will talk to you about what this means for you, and they might want to test other members of your family to find out more.
If your test doesn’t find a faulty gene
If no faults or alterations can be found, it could mean that:
- you don’t have FH
- you have a fault in one of the genes which is known to cause FH, but it couldn’t be found
- you have a gene alteration that hasn’t been identified yet.
Your specialist will talk to you about what it means if no genetic cause for your high cholesterol can be found, and how you can bring it under control.
Before you have a genetic test, you should have genetics counselling at a lipid clinic. A trained genetics counsellor can help you understand:
- what happens when you have a genetic test
- what the results might mean for you and your family
- how having FH may affect you
- how having FH might affect any children you have, now or in the future.
You don’t have to have a genetic test if you don’t want one, and the counsellor can help you decide if it’s right for you.
You can speak to your genetic counsellor about any practical concerns you have too. For example, whether the results could affect life or travel insurance, job applications and mortgage applications, and what you can do about this.
If you or another family member has genetic testing and a gene that causes FH is found, your doctor will suggest that you or other family members have a test too – as it’s likely that some of them will have FH as well. Most people have two close relatives with FH, that is, a brother, sister, parent or child.
This is called cascade testing. It’s much easier to find the faulty gene in other family members once it's been found in one person – as the geneticists already know what they’re looking for.
Why it’s important for family members to get tested
Testing family members helps to find people with FH before it causes a problem.
Sometimes people have FH but don’t have health problems, perhaps because they have a very healthy lifestyle. They could still pass the gene onto their children, so finding out if they have FH means their family can get treatment if they need it.
It’s even possible to have FH and not have high cholesterol. Scientists are discovering more about the genes involved all the time. Some recent research suggests that it’s possible to inherit a faulty gene but still have healthy cholesterol levels. But if you pass the gene onto your children, they could have FH with high cholesterol, which it why testing and cascade testing can help prevent illness.
Telling your family
If you have FH, it’s likely that your doctor will want your help to contact your family. They might give you a letter to pass on which explains about FH, the health problems it can cause, and how the genetic test works. Passing on this letter can help prevent heart disease and stroke in your family and their children for generations to come.
Some people find it hard to explain to their family what FH is and why it’s important to get a test. Some people are not in touch with some members of their family or aren’t on good terms, which can make contacting them or talking to them about FH difficult.
Passing on the letter can help to explain why the test is important. If you would like any support in contacting or talking to your family, our specialist nurses or your genetics may be able to help.