Q: When is the best time to do carrier screening?

Best time: Before you get pregnant. This gives you all options, including IVF with genetic testing of embryos if needed. Good time: Early pregnancy (before 10 - 12 weeks). You can still test the baby if needed. IVF patients: Before startingIVF. If you're both carriers, you'll need extra time if you plan to test embryos for the condition you carry. Both reproductive partners need to have carrier screening before a test can be performed on embryos for the specific condition they carry.

Question 1

What does it mean to be a carrier?

Accepted Answer

We all have two copies of each gene, one inherited from the egg and the other inherited from the sperm. Being a carrier of a condition means that one copy of a gene has an alteration that stops it working, and the other copy is working. We are all carriers of several genetic conditions. Carriers usually do not develop symptoms.

Question 2

What is genetic carrier screening and who should get it?

Accepted Answer

Genetic carrier screening is a simple blood or saliva test that checks if you are a healthy carrier of certain genetic conditions. Generally, being a carrier of these conditions does not cause signs and symptoms, but you have one copy of a gene that doesn't work properly. Both reproductive partners carry a copy of the same gene that is not working properly, then each baby has a 1 in 4 chance (25%) being affected by the condition as neither copy of the gene they inherited works properly.

All couples planning a baby should think about this test. There are usually no signs you carry the kind of genetic conditions included on reproductive carrier screening, and generally most couples will have no family history of the condition. Most people are surprised to learn they're carriers.

Question 3

What's the difference between carrier screening and prenatal screening?

Accepted Answer

Carrier screening tests the reproductive couples’ blood or saliva before or during early pregnancy. It tells you if you have an increased chance as a couple of passing on certain genetic conditions to your children.

Prenatal screening (like ultrasounds, NIPT blood tests, or nuchal scans) checks the baby during pregnancy for conditions like Down syndrome. These are chromosome conditions which can happen by chance and generally are not inherited.They test for completely different things. Carrier screening can't detect if you have an increased risk for chromosome conditions like Down syndrome and prenatal screening can't detect inherited genetic conditions like cystic fibrosis. If both reproductive partners are found to carry a genetic condition in common on carrier screening, specific prenatal testing for that condition might be possible (see details above in Section 5).

Question 4

How will I receive my results? How long does it take to get my results?

Accepted Answer

A Genea genetic counsellor will be in touch once both of your reports are ready. Once we have discussed your results, a summary will be sent to you and your referring doctor. From when you post your sample, we expect your results to take around 4 weeks. Invitae notify us when your results are ready, and you will be contacted to arrange a time to discuss your results with a genetic counsellor.

Question 5

How accurate is testing?

Accepted Answer

A ‘negative’ result means you have a low chance of having an affected child, never no risk. Results are based on current knowledge and technology and rare variants may not be reported at this time.

Question 6

Does a low-risk carrier screening rule out a risk of having a baby with a genetic condition?

Accepted Answer

No. Carrier screening is a test for some genetic conditions, not all conditions. There is no test which can rule out the chance of having a child with a genetic condition. Carrier screening does not rule out a risk for chromosome issues in a pregnancy such as Down syndrome. You can speak with your GP or Fertility Specialist regarding your options for chromosome screening during a pregnancy via NIPT or via Pre-implantation Genetic Testing for Aneuploidy (PGT-A) if you are undergoing IVF. Ultrasound screening in pregnancies is always recommended.

Question 7

When is the best time to do carrier screening?

Accepted Answer

Best time: Before you get pregnant. This gives you all options, including IVF with genetic testing of embryos if needed.

Good time: Early pregnancy (before 10 - 12 weeks). You can still test the baby if needed.

IVF patients: Before startingIVF. If you're both carriers, you'll need extra time if you plan to test embryos for the condition you carry. Both reproductive partners need to have carrier screening before a test can be performed on embryos for the specific condition they carry.

Question 8

What happens if we receive a “high-risk” result?

Accepted Answer

If your carrier screening results indicate an increased chance of having a child affected with one of the conditions screened (due to you and your partner being carrying the same condition, or the female partner carrying an X-linked condition) there are reproductive options available including:

Testing a child at birth;
Prenatal testing; or
Pre-Implantation Genetic Testing for monogenic conditions (PGT-M) via IVF.

A Genea genetic counsellor will discuss these options with you in greater detail and help direct you to an appropriate specialist or service for follow up.

Question 9

How much does genetic carrier screening cost in Australia?

Accepted Answer

There are two types of testing:

Basic (core) testing (three conditions) - Free with Medicare if your GP or specialist refers you for testing. Tests for:

Cystic fibrosis (CF)
Spinal muscular atrophy (SMA)
Fragile X syndrome (FXS)

Expanded testing (500+ conditions) - Costs approximately $500 - $1000 per person and is not covered by Medicare. Both partners need testing, so couples should budget about $1000+ total.

Question 10

What happens if both reproductive partners are carriers of the same condition?

Accepted Answer

If you're both carriers of the same condition, here's what it means for each pregnancy:

25% chance (1 in 4) - baby has the condition
50% chance (1 in 2) - baby is a carrier like you (healthy)
25% chance (1 in 4) - baby doesn't have the condition and is not a carrier

Your options include:

Try conceiving naturally and testing a baby at birth for early treatment (if available)
Testing during pregnancy using CVS (at 11-13 weeks) or amniocentesis (at 15-20 weeks) - these are invasive tests which take a small sample to test from the placenta or amniotic fluid IVF with preimplantation genetic testing (PGT-M) - test embryos via IVF before pregnancy and only transfer unaffected ones
Use donor sperm or eggs from someone who isn't a carrier

A genetic counsellor will explain all these options in detail. The consultation is free if you're high-risk.

Question 11

Can carrier screening detect autism, ADHD, or learning disabilities?

Accepted Answer

No. Carrier screening can't test for autism, ADHD, or most learning difficulties. These conditions are complicated and are generally caused by a range of genetic and environmental factors - like a recipe that needs multiple ingredients, not just one.

Carrier screening only tests for conditions caused by non-working copies of single gene. It can test for Fragile X syndrome, which is the most common known single-gene cause of autism and intellectual disability in males. According to the Fragile X Association of Australia, up to 50% of males with Fragile X syndrome will meet the criteria for autism spectrum disorder. However, only about 2% of people diagnosed with autism have Fragile X syndrome.

This means Fragile X testing will identify only a tiny fraction of autism cases. Most developmental conditions involve many genes plus environmental factors, so they can't be predicted by this test. Testing for Fragile X syndrome is covered by Medicare in the core 3-gene carrier screen.

Question 12

Is carrier screening accurate and what are the limitations?

Accepted Answer

The test is very accurate, but it's not perfect.

What the test CAN'T do:

Find every possible genetic change in the genes tested (all results are based on current technology and understanding of the genes screened)
Test for all genetic conditions (only tests specific ones)
Predict new genetic changes that happen for the first time in your baby
Guarantee your baby will be healthy

Think of it like a car safety check, it checks the major things but can't guarantee nothing will go wrong. If you are not reported as a carrier of the genes screened, this means there is a low chance you carry any of the conditions screened. A "low risk" result is very reassuring but doesn't mean zero risk.

Question 13

Will being a carrier affect my health or life insurance?

Accepted Answer

Your health: Generally being a carrier won't affect your health. Sometimes carrier screening might identify you are a carrier of a condition that might have an impact on your health and in rare cases carrier screening might find that you may be mildly affected with one of the conditions tested. Health insurance: In Australia, health insurance companies cannot refuse you or charge more because of genetic test results. It's illegal.

Life insurance: This is different. For large policies (over $500,000 life cover or $200,000 income protection), companies can ask about genetic tests. However being a carrier for conditions like cystic fibrosis usually doesn't affect your premiums because you're not sick yourself. If you do carry a condition that does affect your health, this may impact you when taking out new policies.

Some people get carrier screening done after they've sorted out their life insurance to avoid any complications.

Question 14

Should I tell my family if I'm a carrier?

Accepted Answer

If you're a carrier:

Each of your siblings has a 50% chance of also being a carrier
At least one of your parents is likely a carrier
Your children each have a 50% chance of being carriers

Sharing information helps family members make informed choices about family planning. Genetic counsellors can write letters for your relatives and help you navigate these conversations.

Question 15

What's the difference between recessive and X-linked conditions?

Accepted Answer

Recessive conditions (like cystic fibrosis):

You need two non-working copies of a gene (one from each parent)
To be affected Carriers have one non-working copy and one working copy of a gene, so they're generally healthy
Affects boys and girls equally
Both reproductive partners must be carriers for offspring to be at risk

X-linked conditions (like Fragile X):

Are caused by non-working genes on the X chromosome (one of the sex chromosomes)
Boys have one X and one Y chromosome, so if they inherit the non-working copy of the gene, they will be affected
Girls have two X chromosomes, so they usually have a healthy backup and are just carriers (although in some cases girls can have symptoms of the condition as well)
Only the mother or egg provider needs to be a carrier - each son will have a 1 in 2 (50%) chance of being affected

Think of it this way: or recessive conditions, both copies of the gene are not working. ;For X-linked conditions, boys only have one copy of the gene, so if it's not working, there's no backup.

Genetic carrier screening

Reproductive genetic carrier screening

Who should consider carrier screening?

What are your carrier screening options?

FAQs

How to order carrier screening

What happens if we receive a "high-risk" carrier screening result?

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