Ready for parenthood, or planning to expand your family? Congratulations! It’s an exciting time and a golden opportunity to prioritise your health for a healthy pregnancy and baby.
Pre-pregnancy and antenatal care have always been an important part of general practice. Studies have shown that getting a check-up prior to conceiving can significantly reduce the risks to the pregnancy and improve the health of your baby, both in early life and even into adulthood. This includes partners too!
Luckily, tests to determine a couple’s chances of passing on a significant genetic condition are now available. With Medicare funding about to be introduced for ALL couples (not just high-risk ones), we thought now was a good time to delve into this important aspect of pre-pregnancy and early pregnancy care.
What is Genetic Carrier Screening?
Also known as a reproductive carrier screen (RCS), it is a blood test offered to women who are planning a pregnancy (ideally), or in the early stages of a pregnancy, to determine the chances that the couple may pass on a genetic condition to their child.
If the test is positive, the male partner is tested and if both are found to be carriers before they fall pregnant, then there are options to reduce the chances of passing the genes on to any future children. In the early stages of a pregnancy, a positive test can lead to further tests to see if the baby is affected.
It’s important to note that RCS is different from the screening tests offered in early pregnancy which assess the chances of the baby having a chromosomal condition like Down Syndrome.
What is a genetic carrier?
Cast your mind back to high school biology if you can, here comes a mini refresher on genetic inheritance!
We all have 2 copies of each of our genes (there around 100,000 of them!), one inherited from our mother and one from our father. The exception are the genes on the X chromosome in males – males only have one X chromosome (inherited from their mother) and a Y chromosome (inherited from their father).
Some people carry “faulty” genes that can be passed on to their offspring. If you have one faulty copy of a certain gene, but the other copy is fine, then you are known as a carrier. Your normal copy means you likely won’t have the genetic condition yourself BUT you can pass the faulty copy (unknowingly) on to your offspring.
If your partner is also a carrier for the same faulty gene, then your offspring may inherit BOTH copies and will have the condition in question, with sometimes devastating consequences; each such pregnancy carries a 1 in 4 chance of having an affected child.
Unless you are tested, you won’t know that you are a carrier. In most cases, there is no known family history of the condition to warn you of the risk.
These conditions are known as autosomal recessive and include things like Cystic Fibrosis (CF) and Spinal Muscular Atrophy (SMA). Conditions involving a faulty gene on the X chromosome, like Fragile X Syndrome (FXS), are known as X-linked conditions. Only females are carriers of this condition, as males don’t pass on their X chromosome.
How common is it?
There are literally thousands of faulty genes in the human population, most of them are thankfully rare. But if we lump the 3 more common ones together – CF, SMA and FXS – we are talking about 1 in 20 Australians being carriers.
Who should be tested?
No-one should be tested, this decision is entirely up to the individual or couple. The Royal Australian and New Zealand College of Obstetricians and Gynaecologists (RANZOG) recommend that “information on carrier screening should be offered to ALL women planning a pregnancy or in the first trimester of pregnancy”.
It’s important to note that the 3 gene test (for CF, SMA and FXS) doesn’t test for all possible genetic conditions. There are expanded tests available which look at hundreds of other rarer gene mutations, but these are usually only recommended in certain circumstances.
How much does it cost?
The 3 gene carrier test is not currently subsidised by Medicare, except in certain circumstances. Thankfully, that’s about to change in November 2023, with the introduction of a Medicare rebate for ALL women, regardless of their history.
The importance of pre-conception care
RCS is an important part of pre-pregnancy planning, but it’s not the only consideration of course. We always recommend seeing your GP if you are planning a pregnancy – ideally 3 months prior, so we can chat about optimising your health and chances of falling pregnant. This includes partners too!
If you’d like to know more about RCS or are planning a pregnancy, book an appointment with your doctor soon.
Photo by Aditya Romansa on Unsplash
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