Genetic testing

Genes are made of your DNA. DNA is a set of instructions for making proteins, which are the building blocks of the cells that make up your body. You have more than 20,000 genes. Your genes carry information that can set your physical traits, characteristics and general health. You have a complete set of all your genes in each cell in your body, each carrying information that shapes who you are.

Random variation (changes) can occur in your DNA. These are called mutations. Most of the time these changes do not have any noticeable effects. Sometimes a variation can change how a gene works, which may result in genetic problems or disorders.

Read the 'Guide to genetics disorders' to learn more about genetic disorders and where to go for help.

Genetic testing is when a lab checks your genes for mutations. This can help diagnose some genetic conditions. You may choose to have a genetic test if you have symptoms of a genetic condition.

There are many genetic tests available that can identify:

• faulty genes that may cause you problems
• genes that do not cause you problems, but may cause problems if passed on to your children

Genetic carrier screening (Opens in new tab) tests are tests to find out if you are carrying a gene that may cause a genetic problem if it passes on to your children.

Genetic testing is only the first part. The important part is understanding what the test results mean. For that, you should talk to a doctor or genetic counsellor (Opens in new tab).

You might consider having genetic testing if:

• you have a newborn baby — a simple blood test (Opens in new tab) can detect some rare genetic conditions
• you are early in pregnancy — non-invasive prenatal testing (Opens in new tab) can check the chance your baby has a genetic condition, such as Down syndrome (Opens in new tab).
• you are planning a pregnancy — genetic carrier screening (Opens in new tab) can be done to test for a wide variety of genetic conditions, including cystic fibrosis, Fragile X syndrome and spinal muscular atrophy
• there is a genetic condition in your family, and you're worried that you or your children will develop it
• you are diagnosed with cancer
• you have a child who is severely affected by growth, development or health problems
• you and your partner are related by blood

Genetic testing can give you important information if you are planning a family or if you, or someone you care for, has a genetic disorder.

Before you start, there are plenty of issues to think about, so talk to a doctor or genetic counsellor for advice.

Genetic tests are usually done at special laboratories. Most genetic tests are blood tests. Sometimes genetic tests involve a sample taken from the inside of your mouth (known as a buccal smear) or from your saliva. These are easy and safe.

If you're pregnant, prenatal testing (Opens in new tab) may include:

• a blood test (Opens in new tab)
• chorionic villus sampling (CVS) (Opens in new tab)
• amniocentesis (Opens in new tab)

Visit the Pregnancy, Birth and Baby website for more information on prenatal screening (Opens in new tab).

It's also possible to order genetic tests online without seeing a doctor. The National Health and Medical Research Council warns people to be careful of this.

Test results can affect your health choices and some decisions that your family might make. There are also risks associated with privacy, and it may be hard to understand the test results. More information on direct-to-consumer genetic testing is available on the Australian Genomics website (Opens in new tab).

The cost of genetic testing can depend on:

• what the test is
• where the test is done

The main benefit of genetic testing is knowledge: if you have a genetic test, you can get advice about what the result means. For example, genetic testing can confirm if a condition you have is because of a faulty gene, or if you have inherited a high risk of cancer. This can help you to make informed health decisions.

If you're having a baby, it can help you plan how to manage your pregnancy, birth, and the life that follows. It can also help if you're thinking about having a termination of pregnancy (Opens in new tab).

If you feel well but worry about a condition in your family, genetic testing can help you to take steps to lower your chances of getting ill. This might be changes such as:

• eating healthier
• exercising more often
• a medicine or a procedure
• having more frequent or different screening tests for the condition

Genetic testing can help you to make informed health decisions although this can come with some risks.

There may be concerns about privacy and data storage. Some companies that you can order tests from online are based overseas. They might be less careful about privacy than Australian companies. Ordering tests from these companies has a risk that your private information could become available to others.

Some genetic tests examine all of the DNA in your cells rather than testing for specific genes that are known to cause diseases. These can find changes in your genes that are not yet understood, so how this affects your health may not be clear.

Talk to your doctor or genetic counsellor about the advantages and disadvantages of genetic testing in your situation.

Testing positive for a genetic mutation does not always mean you will develop the disease linked with that gene. Some genes always cause the linked disease, for example the neurofibromatosis type 1 gene. Other genes increase your risk but don't always cause disease, for example some genes linked with breast cancer. How much you are affected by a gene you inherit can also vary.

Testing for genes is complex and it can be hard to tell what minor changes in a gene mean. Genetic testing may not always provide a clear answer.

The aim of genetic counselling (Opens in new tab) is to give you information and support if you are:

• considering having genetic testing
• at risk of developing a genetic disease
• making health decisions

Genetic counselling can be done by a doctor or allied health professional. Allied health genetic counsellors have specialised training in genetics and counselling.

Genetic counselling can:

• advise you about your or your children's risk of carrying a particular condition
• explore the potential impact that genetic testing results might have on you and your family
• advise you about family planning options in the context of your genetic history
• help arrange genetic testing

Genetic counselling can help in many different situations, including if you are:

• planning a pregnancy (Opens in new tab)
• deciding about prenatal testing (Opens in new tab)
• diagnosed with cancer
• interested in finding out about your future risk of developing a disease

For more information about genetic counselling before or during pregnancy, visit Pregnancy, Birth and Baby's page about genetic counselling (Opens in new tab).

Should I have a genetic test?

That decision is entirely up to you. Talk to family and friends you trust. You can talk to your doctor or to a genetic counsellor.

Talk to a doctor or genetic counsellor

It's best to see your doctor or a genetic counsellor if you're thinking about having a test. That way, you can talk through what the test means, what the results could show and the decisions that may follow. Before your appointment, try to gather information about your family health history to share with your genetic counsellor.

Talk to your family about genetic testing

If you have a genetic test you might find out things you wanted to find out, but you might also find out things you didn't want to know. Your family might want to know everything, or they might want to know nothing.

The best way to know how to approach talking to your family about your results is to talk to them before you have any tests. This way, you will know their point of view.

If testing shows that you or your family member has a genetic condition or risk, you may experience grief. It can affect your physical and mental health. Read more about grief and loss.

• The NSW Centre for Genetics Education has good information (Opens in new tab) for the public on genetic testing. They also have a Genetic Services tool (Opens in new tab) to help find services near you.
• Melbourne Genomics Health Alliance (Opens in new tab) provides educational resources on the different stages of genetic and genomic testing.
• To find a genetic counsellor, go to the Human Genetics Society of Australasia (Opens in new tab).
• If you're pregnant, or planning a pregnancy, see Pregnancy, Birth and Baby's information on genetic counselling (Opens in new tab). You can also call Pregnancy, Birth and Baby to speak to a maternal child health nurse on 1800 882 436 or video call. Available from 7 am to midnight (AET), 7 days a week (including public holidays).
• YourChoice (Opens in new tab) is a decision aid developed to help you learn about screening tests for your baby.
• If you or someone you care for has a rare genetic condition, you may be able to find a support group through Genetic Alliance Australia (Opens in new tab).

Do you prefer to read in languages other than English?

Find information about genetic testing in other languages (Opens in new tab) on the Australian Genomics website.

Looking for information for Aboriginal and/or Torres Strait Islander people?

Learn more about genetics and genomics on the ANU National Centre for Indigenous Genomics website (Opens in new tab).

You can also learn more at the Indigenous Genomics Health Literacy Project (IG-HeLP) (Opens in new tab), which has information on genetic health and genetic testing.