Genetic carrier screening

Genetic carrier screening allows you to understand the chance of passing on an inherited condition to your future children.

If you or your partner are at a high risk of passing on an inherited condition, being aware of your carrier status helps you consider options such as:

• using IVF to get pregnant
• having diagnostic testing for the condition during pregnancy

Genetic carrier screening usually involves you giving a small sample of blood or saliva.

Your genes are instructions that tell your body how to develop and work. You have 2 copies of each gene — one copy from each parent. Some health conditions are caused by faulty genes inherited from one or both parents.

To develop some inherited health conditions, you need 2 faulty copies of the same gene. If you have one working copy of a gene and one faulty copy of a gene, you are known as a 'carrier'. This means that:

• you won't have the health condition yourself
• there's a 1 in 2 chance that you will pass on your copy of the faulty gene to any children you have

If you and your reproductive partner are both carriers of the same condition:

• every child you conceive will have a 1 in 4 chance of being born with the condition
• every child you have will have a 1 in 2 chance of being a carrier

It's not uncommon to be a carrier of a genetic condition. Research shows that around 1 in 20 Australians are carriers of a condition such as cystic fibrosis, spinal muscular atrophy or fragile X syndrome.

Around 9 in 10 genetic carriers have no known family history of the condition, so genetic carrier screening is relevant for anyone planning a pregnancy or who is currently pregnant.

There are 3 different screening options available:

1. Single condition screening — which screens for one specific genetic condition.
2. 3 condition screening — which screens for cystic fibrosis (CF), spinal muscular atrophy (SMA) and fragile X syndrome (FXS).
3. Expanded carrier screening — which screens for hundreds of inherited conditions.

It's recommended that you consider carrier screening if you:

• are planning a pregnancy
• are in your first trimester of pregnancy

Some people who are single are also interested in finding out their genetic carrier status. If you want to learn more, speak to your doctor.

There are hundreds of conditions that are caused by genetic issues, though it's uncommon for you and your reproductive partner to both carry faulty genes for the same condition.

Genetic carrier screening helps you understand your risk of having a baby affected by certain inherited health conditions.

It's important to remember that genetic carrier screening does not pick up every health condition. It also doesn't guarantee that you will have a healthy baby, as many health problems are not genetic.

Genetic carrier screening does not replace prenatal screening tests such as:

• non-invasive prenatal testing (NIPT)
• combined first trimester screening (CFTS)

Talk to your doctor about the risks and benefits of carrier status screening. It's up to you to decide if you want to go ahead.

Genetic carrier screening can be requested by a health care professional such as your:

• doctor (GP)
• obstetrician
• genetic counsellor

They will fill out a test request form that you take to your local pathology collection centre. Your healthcare provider will discuss which conditions you might consider being screened for. For tests that use a sample of saliva, you can order a saliva kit online.

After the blood or saliva sample is taken, it is sent to a specialist laboratory for testing. Your results will be sent back to the requesting health care professional.

Make sure you tell your healthcare provider if you have a family history of a genetic condition. This helps them refer you for the most appropriate screening test in your situation.

In Australia, genetic carrier screening can cost from $100 to more than $1,500. The actual cost will depend on your provider and how many conditions you choose to test.

You may be able to claim some money back through Medicare. This will depend on your family history and the tests ordered.

Some private health funds might pay part of the cost if you have a family history of some genetic conditions.

Medicare rebates for carrier screening

As of 1 November 2023, 34 Medicare rebates for genetic testing have been added. The new rebates are expected to help people find out their combined chance of having a child with genetic conditions, including cystic fibrosis, spinal muscular atrophy or fragile X syndrome.

These new rebates are available to everyone, even if you don't have a personal or family history of these conditions.

You will usually get your test results back in about 2 to 8 weeks, depending on the test you have. Your results will be sent to the health professional who referred you for the test.

My test result was positive

Finding out that your test result was positive may be a shock.

It's likely that you will have lots of questions about having a baby. A genetic counsellor can give you the information you need to help you make an informed decision about what to do next.

Ideally, you will have had genetic carrier screening before trying to conceive. If you and your partner are planning a pregnancy and are at a high risk of passing on an inherited condition, you can look at other ways to get pregnant that lower the risk, such as IVF.

If you're already pregnant, you can talk to your doctor or a genetic counsellor about your options. These might involve:

• more tests
• a non-invasive prenatal testing (NIPT)
• chorionic villus sampling (CVS)
• amniocentesis

If you're found to be a genetic carrier, it's likely that one of your parents is also a genetic carrier. This means that any siblings you have may also be carriers. You may want to share this information with family members, especially if you know they are planning a pregnancy.

My test result was negative

Genetic carrier screening does not check for all genetic conditions. A negative test result doesn't guarantee a healthy baby.

It depends — if you are a genetic carrier and have a new partner, they may wish to be tested before you plan a pregnancy. This can help check your combined risk of passing on an inherited condition.

If you have any questions or concerns about genetic carrier screening, speak to your doctor, obstetrician or genetic counsellor.

NSW Health's Centre for Genetics Education has a patient fact sheet about reproductive carrier testing.

Other languages

The Royal Hospital for Women has a fact sheet on 'planning for a healthy pregnancy' available in a range of community languages.