'Genetic testing of my twins led to an impossible decision. But I wouldn’t change anything.'

The day I learned any child my husband and I conceive will have a one in four chance of having Spinal Muscular Atrophy (SMA) - a rare genetic condition with a two-year average life expectancy - was also the day I discovered I was six weeks pregnant with twins.

COVID time was kind to me, while others struggled through loneliness I was falling in love. My husband and I married in 2021 when masks were mandatory and wedding guests were limited to single digits. After the romantic disappointments of my twenties and early thirties, it finally felt like my longing for a family of my own was being realised.

Ready to embark on our plans, we asked our doctor what we could do to support our chances of having a healthy child. We could do a genetic carrier screening test, part of a study called MacKenzie’s Mission, to identify if we had an increased chance of having a child with a rare serious genetic condition.

Watch: A closer look at carrier screening. Post continues after video.

Video via YouTube/Northwell Health.

He explained everyone has two copies of most genes, one from each parent. A person is a ‘genetic carrier’ for a condition when they have inherited one copy of a faulty gene linked to a genetic condition, but their other copy of the gene works normally (which is why they are unaffected by the condition themselves).


Most people carry two or threww rare genetic conditions but never know because their partner carries different rare conditions. The doctor explained that without any family history of a genetic condition, it’s very unlikely anything would come up but we could do this test to set our minds at ease.

Two weeks after we started trying to conceive, I was looking at a pregnancy test with two blue lines, feeling blessed and just a little bit smug... We were thrilled that we’d seemingly avoided any struggles to conceive. We were still waiting for the genetic screening carrier results but weren’t concerned, it was just a reassurance measure.

It’s never good when someone suggests you pull the car over before receiving screening results. That’s what happened when the genetic counsellor from Mackenzie’s Mission called. 

Listen: Medicare Covering Genetic Screening. Post continues after audio...

“You and your husband are both carriers of the gene for Spinal Muscular Atrophy. That means that you each have an affected and unaffected gene. You will each give one of your genes to your child. If you both give your affected gene your child will be affected by Spinal Muscular Atrophy.”

Spinal Muscular Atrophy (SMA) is a rare and incurable genetic condition in which muscles waste away. It can affect the muscles used for breathing and swallowing and is most commonly present in infancy. She explained that the chances of a result like this were very low, the rate of any couple being carriers of the same genetic condition was less than 2 per cent of those tested in the study so far – across all rare conditions in the study, not just SMA. But we were the rare ones.


She explained that as we are pregnant we would be referred to the Maternal Fetal Medicine Unit after our dating scan and would be able to undergo a test, either a Chorionic Villus sampling (CVS) at 12 or 13 weeks, or an amniocentesis at 15 weeks, to determine if the baby I was carrying was SMA affected. If the baby was SMA affected we could use that information to help prepare or we could terminate the pregnancy.

Dazed and numb, we attended our first scan a few hours later. The ultrasound technician pointed out one sac and then another. Does every pregnancy have two sacs? I thought. As she continued to point out one heartbeat, and then a second, it dawned on me that this didn’t look like other people’s Instagram baby announcement pics. 

“Is it twins?” I asked. 

“Yes, it is a twin pregnancy,” she confirmed. Despite having no family history of twins we had a fraternal twin pregnancy. Each has their own placenta, amniotic sac and genetic information.

This brought up a whole new list of questions and a fraught call back to the genetic counsellor. Could each twin have a different SMA result? Would it be possible to perform a CVS or amniocentesis for each twin? If one twin was SMA affected and the other not would a termination on only one be possible?


The answer was theoretically yes… so the waiting game began. We tried to keep busy but the ever-present buzz of “what ifs” became a roar in the sleepless early morning hours. 

I found SMA was everywhere… A disability advocate on TV talking about the impacts of COVID restrictions on their life was revealed as having SMA when I googled her. What would she do in our shoes I wondered? 

The Mackenzie’s Mission study namesake, Mackenzie, was a little girl born with SMA who died at seven months and 10 days. Her parents, Rachael and Jonathan Casella were unaware they were SMA carriers until their daughter was diagnosed at 10 weeks old. The Casellas wanted other couples to know about genetic carrier screening so they had choices during family planning or pregnancy. I listened to every podcast and read every article about Mackenzie. 

There are four types of SMA, most common is type one which has an untreated life expectancy of two years. Treatment options exist and are evolving rapidly but still have complex requirements for access and come with their own challenges. The least common SMA types have no reduction in life expectancy but likely become wheelchair-bound and experience reduced mobility.

If our child experienced an injury and became wheelchair-bound, or developed an illness that we didn’t know of, it wouldn’t change the value we saw in their life… so should this potential outcome? Or with this knowledge even if they were to be affected by the least severe form of SMA would we be constantly waiting and watching for their mobility to deteriorate? What would that hypervigilance be like for them and for us?


When we finally made it to the 12-week scan all of the twin questions and considerations evaporated… one of the foetuses no longer had a heartbeat. The news was like a winding punch and I bit the inside of my mouth as I batted tears away while the obstetrician completed the rest of the examination. Outside the consulting room, I heaved into my husband’s chest while he gripped me tightly, then we compartmentalised that grief into a box and focused on what was next... the waiting game for our remaining baby.

At 15 weeks we had a CVS test and then an agonising wait for results. Everything went slow.. and then suddenly very fast. The genetic counsellor called us in to receive the test results. My husband and I didn’t tell anyone else we had received the call, instinctively we knew we were going alone as a couple. 

Please let it be the 75 per cent chance result of a healthy baby. Please let me be able to keep this child I have grown inside me for the last 15 weeks. I pleaded to an unknown god over and over as we drove to the appointment.

The genetic counsellor ushered us through to a consulting room where another of her team was waiting.


“Unfortunately, it is not the result we were all hoping for. The results show that there are two SMA-affected genes. This means that this pregnancy, if it were to continue, would be SMA affected.” 

He continued to explain the result and the options. I wanted him to sugar-coat it, to say that there are treatment options and you could continue with this pregnancy and everything would be okay. He didn’t. He was very clear that whilst there were treatment options, it wouldn’t be an easy path. It would involve a life of hospital trips and navigating the medical system. 

My husband and I staggered out of the hospital and drove to the beach. We sat on a bench and watched the waves lap. Within a few minutes of discussion, we made a decision, irrespective of which type of SMA our baby had we were going to terminate the pregnancy. We wanted to do everything we could to bring a healthy baby into the world, for us as parents and for our unborn child, we didn’t want to bring an SMA-affected baby into the world.

This decision whilst clear was not easy. I come from a more pro-choice family than most, my grandmother was the clinical director for the first legal abortion clinic in Australia, but the termination of a very wanted pregnancy came with lots of mixed feelings. To have carried that pregnancy for four months with all the joy, anticipation, and physical effects of early pregnancy and then to say goodbye was agonising.

As tough as it was, I am incredibly grateful I had the opportunity to make that decision. From November 1, 2023, Genetic Carrier Screening for SMA, Cystic Fibrosis and Fragile X) has been reimbursed by Medicare, and with this change hopefully, more General Practitioners will make their patients aware of this test. Were it not for the sheer luck of my husband asking and the study being mentioned we wouldn’t have found out at any stage during the pregnancy that our baby was SMA affected, or that we were both carriers of SMA. We would have found out 10 days after birth when we received the baby’s heel pinprick test results. 


Knowing and being able to act on our genetic carrier screening results fundamentally changed our experience of growing a family and I am so grateful for the work of Mackenzie’s mission and the Casellas. Their experience and advocacy gave us knowledge and choices they didn’t have. 

I’ve often wanted to share my experience so other couples planning a family or in early pregnancy know about genetic carrier screening. Well-meaning family cautioned me against telling my story whilst I was still in the midst of it.

I’m not sure the story of our twin loss, and the pain of ending a much-wanted pregnancy, will ever really be finished. But now feels like the right time to share as I am definitely living a new story – I am writing this with my six-month-old son sleeping next to me. He was conceived through IVF with Karyotyping pre-implantation genetic testing of embryos and is a healthy baby boy.

Image: Supplied.


Like my husband and I, he is an SMA carrier, but hopefully, when the time comes for him to have children, the treatment options that are available will have changed what it means to have SMA – or medical technology removes the disease altogether. At the very least, he will have the knowledge and ability for his partner to get tested to make their own informed decisions about their own family. 

Feature Image: Supplied.