What is genetic carrier screening and do you need it?

There are some things you probably wouldn’t mind passing on to your future children. Your blue eyes. Your curly hair. Your love for terrible reality TV. But I’m guessing genetic diseases aren’t on the list.

Well, you can’t do a whole lot to convince your unborn child that MAFS is the sh*t. But you can have genetic carrier screening done to look into their chances of inheriting an unwanted health condition.

Genetic screening for carrier status (meaning, whether or not you ‘carry’ the mutated genes that cause some diseases) can be done before you conceive or during your pregnancy. So what does it involve and what is the purpose of genetic screening anyway? Let’s explore.

What is genetic screening?

Back in the day (not so long ago actually), parents would have sex, conceive a child, birth said child, and only THEN find out about any health conditions in the baby. Some genetic conditions are heavily sprinkled throughout family trees, so couples may have known that there was a chance their child would inherit something. But there was no way of knowing for sure in advance.

Fast-forward to the 21st century, and you can now undergo a simple genetic screening process before even falling pregnant to test for hundreds of genetic markers. Doctors can use your carrier status information to advise you on your chances of passing a disease onto your offspring. Wild!

We’re talking diseases like:

  • Cystic fibrosis – a condition causing lung infections and breathing difficulties.

  • Fragile X syndrome – a developmental disorder that can lead to intellectual disability.

  • Spinal muscular atrophy (SMA) – a condition affecting the spinal cord, causing muscle weakness, and mobility and breathing issues.

… To name three of the most common ones that genetic carrier screening tests for. But there are literally hundreds of genetic disorders out there, many of which you’ve probably never heard about. While they’re quite rare, all these inherited conditions combined affect about 1 in 400 people. Some can be lived with and just require treatment throughout life, while others are life-threatening from birth.

These days we can learn about the potential health conditions our children may inherit ahead of time, and make the appropriate decisions or preparations. Thanks a bunch, Science!

Different types of genetic screening

Genetic carrier screening for parents planning pregnancy

When you’re planning for pregnancy, your doctor might recommend screening for carrier status to see if you and/or your partner have mutated genes that could pass onto your future child. It might all sound a bit ‘X-Men’, but it really just involves doing a blood test and/or saliva swab and having your sample(s) analysed in a special lab. 

You can choose to do sequential screening, where you do the genetic carrier screening first, and your partner only if you test positive (cuts costs!). Or you can go all in and do couple screening (cute date idea?), which will result in a low or high probability rating for genetic issues in your offspring.

Genetic screening in pregnancy

Pregnant women are offered genetic screening as part of typical prenatal testing. Blood tests and ultrasounds can help doctors identify signs of genetic abnormalities that cause conditions like Down Syndrome. 

If you want to explore things further during your pregnancy, you can request more conclusive diagnostic testing.

Genetic screening in newborns

In many countries including Australia, New Zealand and the US, genetic newborn screening is the done thing. It’s also called the “heelprick test” or “bloodspot screening”, and it typically happens 48–72 hours after birth (you’ll sign something to give your consent, though it may all be a blur). 

This low- to no-risk test involves taking a tiny drop of your newborn’s blood and sending it to be analysed for genetic conditions like cystic fibrosis or hypothyroidism. If anything is picked up (which is rare), doctors can treat it straight away.

Genetic screening versus genetic testing

Genetic screening doesn’t confirm whether your child will actually HAVE a genetic condition for certain. It gives you a likelihood that they might inherit something from the mix of two reproductive partners. 

Diagnostic genetic testing is more conclusive. Tests during pregnancy, such as amniocentesis and chronionic vilis sampling, can detect whether your baby has a condition, but these tests also come with a low chance of causing a miscarriage.

Why screen for genetic carrier status?

The Royal Australian and New Zealand College of Obstetricians and Gynecologists suggests that all parents planning for pregnancy should be offered the option of genetic carrier screening. Why? Because perfectly healthy people can pass on genetic conditions to their kids without being aware that they’re even at-risk as carriers. So it’s a test really relevant for anyone planning to procreate.

Genetic carrier screening might be more on the radar for some people. For example, if you’ve got a family history of genetic conditions (and no, your uncle’s clinically awful dance moves don’t count), or are of a certain ethnic descent that carries higher risk. 

Do you NEED to have genetic screening done? Nope.

You might be of the opinion that you’ll love your child and be able to support their development no matter what health issues come their way. The purpose of genetic carrier testing is to help parents make informed reproductive decisions and plan ahead if they want to.

How it works: Genetic carrier screening in Australia

1. See your doctor for a referral

Your options for doing a carrier screening test may be brought up during pregnancy planning or prenatal checkups. Your doctor will explain how it works and give you a pathology request form. 

2. Discuss your options

You can choose to screen for a single gene type, three at once (usually cystic fibrosis, fragile X syndrome and spinal muscular atrophy), or do an ‘expanded carrier screening’ which tests for hundreds of gene mutations at once. 

3. Get tested

Get your blood test done, and your sample will be taken to a special lab for analysis by very smart people. (*Nervously await results*)

4. Discuss outcomes

If your results show that you or your partner carry genetic markers for diseases, you’ll be referred to a genetic counsellor to talk through your reproductive options. But ultimately it’s up to you what you do with the information, and whether or not it affects your plans to start a family.

Genetic carrier screening costs

Reproductive genetic carrier screening is generally an out-of-pocket cost (i.e. not covered by Medicare). According to The Royal Australian College of General Practitioners:

“Patients can expect to pay fees in the range of:

  • single-condition screening: $100–$200
  • three-condition screening: $350–$400
  • expanded carrier screening: $580–$900.”

Of course, it depends on the pricing of the facility you go to. Boujee screening clinic? More expensive genetic screening. Goes without saying.

What happens if you test positive as a genetic carrier?

This is where things can get tricky. 

About 1 in 20 people carry genetic markers, but there’s a higher risk of your child getting a rare disease if both you and your partner test positive (1 in 4), or if you have a strong family history of inherited diseases. 

Also, if you (the X chromosome in this situation) are a carrier of certain genetic markers, there can be up to a 1 in 2 chance of your son being affected by the condition and your daughter being a carrier.

It’s all a bit mathsy. We’re talking probability, equations – things we won’t get into here for fear of frying your (my) brain. Your doctor can walk you through what it all means and help you decide what to do with your carrier status information. 

From here, your next steps could be:

  • Have a baby naturally and test them after birth to see if they develop the condition.

  • Conceive naturally and have diagnostic testing done during pregnancy to test your baby for the condition. (If they test positive, you might decide not to proceed with the pregnancy, or you might start to plan for life with a genetic condition.)

  • Conceive with IVF and test embryos for genetic markers prior to implantation. (Yeah, they can do that!)

  • Use donated sperm or embryos from people without genetic markers.

  • Adopt.

  • Decide not to have children.

Just remember that you can’t control genetics, and your carrier status is not something you can change. Whatever you decide to do, it’s your call and you’re an awesome mum (or not-mum!) regardless. 

Read next: Everything you need to know about how to get pregnant

The Royal Australian and New Zealand College of Obstetricians and Gynaecologists, Genetic carrier screening

Manju Karthikeyan (1999), Human Genetic Screening

The Royal Australian and New Zealand College of Obstetricians and Gynaecologists, Reproductive Carrier Screening

Mayo Clinic, Genetic testing

The Royal Australian College of General Practitioners (RACGP), Beware the rare – Carrier screening

MedLine Plus, How are genetic screening tests different from genetic diagnostic tests?

BetterHealth Channel, Newborn bloodspot screening

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