The process of genetic testing

There are usually two stages to genetic testing:

Step 1: Mutation searching

Looks for faults in known breast cancer genes. Where possible a family member who has had (or has) breast cancer has the test.

If no fault found

A genetic cause for breast cancer in the family is not known. (In some cases, other relatives can undergo mutation searching to look for a faulty gene).

If a fault is found

A genetic cause for breast cancer in the family is known.

Step 2: Predictive testing

Checks whether other relatives in the family who are eligible for testing have inherited the specific gene fault.

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Does your family have Ashkenazi Jewish heritage?
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Have you personally had a diagnosis of breast cancer?
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Is a living relative in your family who has had breast cancer available for genetic testing?
Eligibility for genetic testing
Before you or your family can access genetic testing, you will need to have your family history assessed by your GP and then a specialist.

People are only eligible for genetic testing if it's estimated that there is at least a one in 10 (10%) chance that they could have inherited faulty breast cancer genes.

Most people in the UK are not eligible for genetic testing, as it is unlikely that they have inherited these genes.
Related information
Find out the first steps to exploring your family history
Read more
If you are considering private genetic testing, read Breast Cancer Now's advice
Read more
Genetic testing for people of Ashkenazi Jewish decent
Three particular faults in BRCA 1 and BRCA2 genes are known to be more common in people who have Ashkenazi Jewish ancestry. This does not mean that all people of Ashkenazi Jewish descent are at increased risk of breast cancer – only one in every fifty Ashkenazi Jews carry one of these faults.

If you are eligible for genetic testing and have Ashkenazi Jewish ancestry, these three faults can be looked for first, which can make genetic testing simpler for some families and means that the first step of genetic testing, which is called mutation searching, may not be necessary. However if none of these three specific faults are found, further testing to look for other faults may be needed.

Predictive testing

Eligible family members can be tested to see whether they carry any of the three BRCA gene faults that are more common in Ashkenazi Jewish families. Relatives might be tested in a particular order (parents will usually be tested before children).

A blood sample from each person being tested will be checked for these faults. The laboratory should provide the results of these tests within two to four weeks. It may take a little longer than this before you or your relatives receive your results in an appointment at the genetics clinic.

What the results mean:


If you have a faulty gene linked to breast cancer
If a faulty BRCA gene is identified in your blood sample, this means that you're at increased risk of developing breast cancer compared with the average person. This does not mean that you will definitely get breast cancer, but it is much more likely than for someone who hasn't inherited the gene.

Women may also be at increased risk of developing ovarian and pancreatic cancer, while men may also be at increased risk of developing prostate, breast and ovarian cancer.

You will be eligible for specialist services to help you to manage that risk. There will be a 50:50 chance that you will pass this gene on to each child you have. A special type of in vitro fertilisation (IVF) is available to some people planning a family to avoid this risk

If you have children already and are interested in discovering whether they have inherited a faulty gene, they can have genetic testing once they reach adulthood.
If a faulty gene linked to breast cancer is found in your family, but you don't have it
Provided that at least one person is found to carry a faulty BRCA gene in your family, this means that the genetic reason for your family's increased risk is now known.

If you're found not to carry the faulty breast cancer gene identified in your family, this means that you haven't inherited an increased risk of breast cancer. Your chance of developing breast cancer will be estimated to be the same as the general population - about one in eight (12.5%) for women, or 1 in 100,000 for men. If you are a parent or become one in the future, your children will not inherit a faulty breast cancer gene from you.
If a faulty gene is not found in your family
If no one in your family who is tested is found to carry one of the three common faults in the BRCA genes, this means the cause for your family's increased risk of breast cancer has not been found.

Further genetic testing may be needed to look for other, less common faults in breast cancer genes depending on your family history.
Related information
People found to carry genetic faults are at high risk of developing breast cancer – find out what this means
Read more
If a faulty gene is found in your family, what are the chances other relatives have inherited it too?
Read more
Learn about options for prospective new parents who carry a BRCA fault
Read more
Genetic testing if you have had a breast cancer diagnosis

Mutation searching

As you have a personal history of breast cancer and are eligible for genetic testing, you should be offered a genetic test for faulty breast cancer genes. If you choose to go ahead, a sample of your blood can be tested to see whether you carry one of hundreds of known faults in genes linked to breast cancer, such as BRCA1, BRCA2 and TP53. This is called mutation testing (or diagnostic testing).

The laboratory should provide the results of your test within eight weeks. It may take a little longer than this before you receive your result in an appointment at the genetics clinic. Waiting times may vary, for example in Wales tests can take up to 16 weeks to complete. Check with your genetics specialist if the waiting time for results is not clear.

Under certain circumstances, for example if you are taking part in a trial or want the results to help you make decisions about your treatment, you might receive your results sooner than this.

What the results mean:


If you have a faulty gene linked to breast cancer
This means that your breast cancer probably occurred because of this faulty gene linked to breast cancer. You might be more likely to develop the disease again in the future.

If you have a BRCA1 or BRCA2 fault, you will also be at increased risk of ovarian cancer.

You'll be eligible for care and advice to help you to manage your risk.

Some other members of your family, but probably not all, could carry this gene too. They can have predictive testing if they're eligible.

There will be a 50:50 chance that you will have passed this faulty gene on to each child you have. A special type of in vitro fertilisation (IVF) is available to some people planning a family to avoid this risk.

If you have children already and are interested in discovering whether they have inherited a faulty gene, they can have genetic testing once they reach adulthood.
If you don't have a faulty gene linked to breast cancer
If no fault known to be linked to breast cancer is found in your sample, this means that the genetic reasons for your breast cancer could not be found. However, there could still be an unidentified genetic cause for your breast cancer, and you could still be at increased risk of developing another breast cancer. This risk can be estimated based on your family history.

It won't be possible for your relatives to have genetic testing as there isn't a confirmed fault in your family to look for in their DNA. However, it's still possible for each person's chance of developing breast cancer to be estimated if they wish, based on the patterns of cancer in your family. For more information, see our section on risk assessment.

If no genetic fault is identified in your family, you should be told that you can request a review at a future date.

Predictive testing

If you're found to carry a known fault in a breast cancer gene, for example BRCA1, BRCA2 or TP53, some other members of your family are likely to be eligible for genetic testing too. The first step will be for them to visit their own GP.

A GP referral is usually needed, but some genetics clinics allow patients to get in touch directly, so you may wish to ask your genetics clinic whether this is possible for your relatives.

If your relatives choose to have genetic testing, they will need to have genetic counselling first. A blood sample will be used to check whether or not they have the same gene fault as you. The laboratory should provide the results of your test within two to four weeks. It may take a little longer than this before your relatives receive their result in an appointment at the genetics clinic.

What the results mean:


If your relative has a faulty gene linked to breast cancer
This means that they're at increased risk of developing breast cancer too. Women with a BRCA1 or BRCA2 fault may also be at increased risk of ovarian and pancreatic cancer, and men with a fault in one of these genes may be at increased risk of breast, prostate and pancreatic cancer.

They'll be eligible for specialist services to help them to manage that risk.
If your relative doesn't have a faulty gene linked to breast cancer
This means that they have not inherited an increased risk of breast cancer. Their chance of developing breast cancer will be the same as the general population – that's about one in eight for women and about one in 100,000 for men.
Related information
People found to carry genetic faults are at high risk of developing breast cancer – find out what this means
Read more
If a faulty gene is found in your family, what are the chances other relatives have inherited it too?
Read more
Learn about options for prospective new parents who carry a BRCA fault
Read more
Genetic testing starting with a relative with breast cancer

Mutation searching

As an eligible relative who has had a diagnosis of breast cancer is available for genetic testing, they will be tested first for faulty breast cancer genes.

If they choose to go ahead, a sample of their blood will be tested to see whether they carry any known faults in genes linked to breast cancer, eg BRCA1 BRCA2 and TP53.

The laboratory should provide the results of your test within eight weeks. It may take a little longer than this before you receive your result in an appointment at the genetics clinic. Waiting times may vary, for example in Wales tests can take up to 16 weeks to complete. Check with your genetics specialist if the waiting time for results is not clear.

Under certain circumstances, for example if you are taking part in a trial or want the results to help you make decisions about your treatment, you might receive your results sooner than this.

If your relative chooses not to go ahead with genetic testing, it's still possible for you and other eligible relatives to be tested.

What the results mean:


If your relative has a faulty gene linked to breast cancer
If a gene fault known to be linked to breast cancer is found in their sample, this means that their breast cancer probably occurred because of this fault. Your relative might be more likely to develop the disease again in the future. They will be eligible for specialist care and advice to help them to manage their risk.

If your relative has a BRCA1 or BRCA2 fault, they will also be at increased risk of ovarian and pancreatic cancer (for female relatives), or prostate and pancreatic cancer (for male relatives).

You and some other members of your family, but probably not all, could carry this faulty gene too.
If your relative doesn't have a faulty gene linked to breast cancer
If a gene fault known to be linked to breast cancer is not found in your relative's blood sample, this means that the genetic reasons for your family's increased risk of breast cancer could not be found. However, there is still an increased risk of breast cancer in your family.

It won't be possible to confirm whether you have or haven't inherited this increased risk. However, it's still possible for specialists to estimate your chance of developing breast cancer if you would like, based on the patterns of cancer in your family.

If no genetic fault is identified in your family, you should be told that you can request a review at a future date.


Predictive testing

If your relative is found to carry a known fault in a breast cancer gene, you and other members of your family might be eligible for genetic testing too.

The first step will be for you and any interested relatives to visit your GP. Some genetics clinics allow patients to get in touch directly, so if you know the contact details of the genetics clinic where your relative was tested, you may wish to contact the clinic to ask whether this is possible.

If you are eligible and decide to have genetic testing, you will need to have genetic counselling first.

A blood sample will be used to check whether or not you have the same gene fault as your relative diagnosed with breast cancer. The laboratory should provide the results of your test within two to four weeks. It may take a little longer than this before you receive your result in an appointment at the genetics clinic – check with your genetics specialist if the waiting time for results is not clear.

What the results mean:


If you have a faulty gene linked to breast cancer
This means that you're at increased risk of developing breast cancer.

If the fault is in a BRCA gene, you are also at increased risk of developing ovarian and pancreatic cancer if you are female, and prostate and pancreatic cancer if you are male.

This does not mean you'll definitely get cancer, but it is much more likely than for someone who has not inherited the gene.

You will be eligible for specialist services to help you to manage that risk.

There will be a 50:50 chance that you will pass this faulty gene on to each child you have. A special type of in vitro fertilisation (IVF) is available to some people planning a family to avoid this risk.

If you have children already and are interested in discovering whether they have inherited a faulty gene, they can have genetic testing once they reach adulthood.
If you don't have a faulty gene linked to breast cancer
This means that you have not inherited an increased risk of breast cancer.

Your chance of developing breast cancer will be the same as the general population – that's about one in eight for women and about one in 100,000 for men.

If you're a parent (or become one in the future), your children will not inherit the faulty gene from you.
Related information
People found to carry genetic faults are at high risk of developing breast cancer – find out what this means
Read more
If a faulty gene is found in your family, what are the chances other relatives have inherited it too?
Read more
Learn about options for prospective new parents who carry a BRCA fault
Read more
Genetic testing where no family member with breast cancer can be tested
As there are no living relatives in your family diagnosed with breast cancer who would like to have genetic testing, it's not possible to check whether or not a faulty gene was the likely cause of their breast cancer.

However, it's now possible for other eligible relatives without breast cancer to have genetic testing. Here's the process if you decide to have genetic testing as the first member of your family.

Mutation searching

You'll be able to have genetic testing to look for a faulty breast cancer gene so long as you have at least one in 10 (10%) chance of having a gene fault. This test is called mutation searching.

If you choose to have genetic testing, you'll be offered genetic counselling first. A blood sample will be used to check for faulty breast cancer genes.

The laboratory should provide the results of your test within eight weeks. It may take a little longer than this before you receive your result in an appointment at the genetics clinic. Waiting times may vary, for example in Wales tests can take up to 16 weeks to complete. Check with your genetics specialist if the waiting time for results is not clear.

Under certain circumstances, for example if you are taking part in a trial or want the results to help you make decisions about your treatment, you might receive your results sooner than this.

What the results mean:


If you have a faulty breast cancer gene
If a gene fault linked to breast cancer is found in your blood sample, this means that you're at increased risk of developing breast cancer.

If the fault is in a BRCA gene you may also be at increased risk of developing ovarian and pancreatic cancer if you are female, and prostate and pancreatic cancer if you are male.

This does not mean that you'll definitely get cancer, but it is much more likely than for someone who has not inherited the gene.

You'll be eligible for specialist services to help you to manage that risk.

There will be a 50:50 chance that you will pass this faulty gene on to each child you have. A special type of in vitro fertilisation (IVF) is available to some people planning a family to avoid this risk.

If you have children already and are interested in discovering whether they have inherited a faulty gene, they can have genetic testing once they reach adulthood.

Other eligible relatives will be able to be tested for the gene too if they would like.
If you don't have a faulty breast cancer gene
If no gene fault known to be linked to breast cancer is found in your blood sample, this doesn't mean that you're definitely not at increased risk of breast cancer. Unfortunately, the reason for the cancers in your family is not yet understood.

It's possible for other eligible family members to have mutation searching too, to see if a genetic reason for your family's cancer can be found. If in the future a faulty gene is found in another family member that did not show up in your own test, this would confirm that you are not at increased risk of breast cancer.

Unless this happens, you'll still be considered at increased risk of breast cancer, and the chances of you developing the disease can be estimated based on the patterns of cancer in your family.

Predictive testing

If you're found to carry a known fault in a breast cancer gene, other members of your family might be eligible for genetic testing too.

The first step will be for interested relatives to visit their own GP. Some genetics clinics allow patients to get in touch directly, so you may wish to ask your genetics clinic if this is a possibility for your relatives.

If relatives are eligible and decide to have genetic testing, they will need to have genetic counselling first. A blood sample will be used to check whether or not they have the same gene fault as you.

The laboratory provides the results of the test within two to four weeks. It may take a little longer than this before they receive their result in an appointment at the genetics clinic – they may want to check with their genetics specialist if the waiting time for results is not clear.

What the results mean:


If your relative has a faulty breast cancer gene
This means that they're also at increased risk of developing breast cancer.

If the fault is in a BRCA gene, they may also be at increased risk of developing ovarian cancer and pancreatic cancer if they are female, and prostate and pancreatic cancer if they are male.

This does not mean that they will definitely get cancer, but it is much more likely than for someone who has not inherited the gene.

They will be eligible for specialist services to help to manage that risk.
If the faulty gene is not found in their blood sample
This means that they have not inherited an increased risk of breast cancer.

Their chance of developing breast cancer will be the same as the general population – about one in eight (12.5%) for women and one in 100,000 for men.
Related information
People found to carry genetic faults are at high risk of developing breast cancer – find out what this means
Read more
If a faulty gene is found in your family, what are the chances other relatives have inherited it too?
Read more
Learn about options for prospective new parents who carry a BRCA fault
Read more

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