Public health

Call for more awareness of genetic carrier screening


One of Kirsty McConnell’s favourite memories of her youngest daughter Lily is her first time at the beach.

The water is sparkling and cold and her big blue eyes widen as she’s carefully lowered into the water in a baby seat.

She is just 14 months old. It’s the first and last time she will ever experience the sea.

Kirsty and her husband Aaron met at a party. They soon discovered they had something in common – both were raising a child from a previous relationship.

They were unaware that they shared something else in common: an autosomal recessive gene mutation affecting one in 40 people.

When two carriers have a baby, the child has a one-in-four chance of developing the terminal inherited muscle wasting disease spinal muscular atrophy (SMA).

After falling pregnant, Kirsty took the pre-natal screening tests for Down Syndrome.

At 32, she wasn’t worried, but “just wanted to be sure”.

Lily McConnell had SMA

Lily McConnell had SMA

The pregnancy was uneventful and Lily was born a healthy 3.2 kg with screening tests coming back normal.

Doted on by her two half-sisters, she made all her early milestones and passed her four-month check without incident.

But at six months, she became “floppy”.

“When we would put her on the floor for tummy time she would not lift her head up anymore, she wasn’t interested in moving.

“I would hold her on my hip and after a while she would get sluggish and rest her head on my shoulder. It got to a point where in a chair she would just slouch to the side.”

Lily was taken to a paediatrician but it was another 10 weeks before the diagnosis that made the sky fall in.

“We were very shocked because throughout the whole thing we were told not to worry, she might have hypotonia, she might be lazy.

“So to be then told ‘actually she’s going to die’, that was pretty horrific.”

Soon after, Lily was hit with a cold that put her in ICU and the couple was told to prepare for the worst.

But she pulled through, and after a month in hospital she was back home.

“We had another seven months with her after that which we consider we were pretty lucky to get,” Kirsty recalls.

It meant the family was able to spend precious time – like the camping trip to Anglesea in January where Lily, in a baby bath seat, had her first taste of ocean and sand play.

Lily was 16 months old when she died in March this year and it’s taken a massive toll on the whole family.

“My younger daughter Eliza in particular struggles,” Kirsty says. “They were very close. One of Lily’s first words was ‘E-iza”.

The prognosis for SMA type 1 is grim – it typically means death before the age of two from respiratory failure.

Testing issues

There is a genetic carrier screening test for SMA, cystic fibrosis and fragile X syndrome on the market.

Like the screening test for CF, it’s not publicly funded, and it costs a little under $400.

But that’s something the researchers from Victoria’s Murdoch Children’s Research Institute who developed the test hope will change.

Their recently published study of 12,000 people revealed carrier prevalence rates in Australia for the first time – a combined affected pregnancy rate of one in 1000, with 88% of participants having no family history of the conditions.

This figure is comparable to Down Syndrome, prompting the authors to argue the triple-test should be offered to everyone planning a baby.

Professor David Amor, consultant clinical geneticist at the University of Melbourne and a co-author of the paper, said while some couples will never undergo screening the main game is about giving would-be parents informed choice.

Kirsty McConnell with Lily

Kirsty McConnell with Lily

Armed with the information, carrier couples may then choose to conceive naturally, follow up with invasive testing and then consider a termination, or use IVF and pre-implantation genetic diagnosis.

Currently in Victoria about 10% of first-time mothers use the triple-test, compared to 80% for Down Syndrome, he said.

With the explosion of the genetic testing market, new ethical dilemmas are emerging.

“Part of the problem is there is no such thing as a perfect test in this setting,” says Professor Amor.

“The more you try to catch in your net of severe problems the greater likelihood you will find out some information that’s not helpful.

“Some people use the term ‘paralysing information’. If you tell a couple based on the information there is a 5% chance their child is going to have a disability but a 95% chance that the child will be fine, it’s very hard for them to do anything with that information.”

How does Professor Amor and his team deal with that possibility?

“Our approach has been a conservative one in that we have only focused on disorders we know we understand and can counsel for.

“But we have to acknowledge that by doing that there are potentially severe outcomes that we are going to miss, that’s a choice we’ve made.

“We are trying to avoid doing harm as our underlying philosophy”.

But for Kirsty, there is no grey area when it comes to a test for SMA.

It is simply a “no-brainer” and she wishes she had known about it before she fell pregnant.

“I believe if I had known I was a carrier and Aaron was a carrier and we could potentially pass this on to our child I believe I would have gone and read up on what the condition is, what it does to children and I think that alone would have probably swayed me into potentially researching and having IVF.

“Any form of muscular dystrophy is horrific, to have it happen to little babies is just horrible.

“I’m not a massive risk taker in life and the one-in-four chance, those odds are too high.”

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