One small baby: one giant leap for genetic screening

One baby’s tragic death led to a $20-million trial to prevent similar cases. Tabitha Carvan reports.

Right inside the door of Dr Steve Robson’s clinic, there’s a noticeboard covered with photos of smiling babies. He is an obstetrician, and these are his happy patients.

They took all this grief and energy and transferred it into a huge campaign.

I can’t help but think of another smiling baby whose photo I’ve seen. A beautiful little girl, Mackenzie, whose mother, Rachael Casella, BSc (Psych) ’05, once stood in a doctor’s office like this while he delivered a diagnosis of spinal muscular atrophy – a horrific, terminal condition – for her daughter.

“I shut down,” Rachael writes in a blog post about that moment. “Everything went blurry, sounds were muffled and I felt like I was going to collapse. I stood over [Mackenzie] as she lay quietly in her nappy on the bench. I held her hands and she stared up at me. We locked eyes but she knew nothing of the knife that had just torn through my heart. She lay there oblivious to my turmoil, smiling up at me.”

Rachael had no warning this diagnosis was coming. Other than a minor delay in muscle strength and movement, Mackenzie appeared a perfectly healthy 10-week-old baby, who now only had a few months to live.

“No-one knew what to say. What was there to say?” Rachael continues. “We kept saying, ‘This isn’t happening. This isn’t happening’ … We planned for her, she is here, she is perfect.’”

Mackenzie is now why I’m here in Robson’s office. “I’m a parent, and I know that if this happened to me, I would be crushed,” he says.

Robson is Professor of Obstetrics and Gynaecology at the ANU Medical School and on the clinical committee overseeing a federally funded trial of genetic screening.

“Mackenzie’s parents are very organised people and put a lot of planning into the pregnancy. But they didn’t know they both were carriers of the gene defect for spinal muscular atrophy, which is a recessive genetic disorder,” he says.

“Rachael said, ‘Had I known this would happen, I would have insisted on testing’. They could have had IVF and tested the embryo and only transferred an embryo that did not have the genetic mutation.

“So they took all this grief and energy and transferred it into a huge campaign for increased access to testing for genetic mutations.”

Mackenzie Casella.Mackenzie Casella. Photo courtesy of Rachael Casella.

The result is Mackenzie’s Mission, a $20-million Australian Government initiative to trial genetic screening for 10,000 Australian couples. Where couples are found to both carry genetic mutations for recessive conditions, they can conceive using a fully funded round of IVF to screen out the disease first.

“I’m incredibly excited about the opportunity, which is the first of its kind in the world,” Robson says. “The University is able to show national leadership on an issue which affects every young couple in the country who are thinking of starting a family. It’s breathtakingly important.”

He says the technology required to sequence a couple’s DNA and identify mutations before they even start trying for a baby is ‘cool science’ but not the main focus of the trial.

“The technology is easy, but the people management is hard,” he says.

Professor Thomas Faunce, PhD ’01, a bioethicist and legal health expert with the ANU College of Law and the ANU Medical School, agrees.

“These are tragic diseases and if you can assist people to detect these conditions prior to pregnancy, there’s a strong ethical case for doing it,” he says.

“What’s important with this trial is equity of access, data privacy, and availability of counselling.

“You wouldn’t want it to be offered only to people who read about the trial in newspapers and on websites, excluding people who don’t readily have access to information about it.”

Similarly, Robson says the first question he asked when invited to join the trial was, “Can we design a project that’s as equally meaningful and accessible to an Aboriginal couple in the Kimberley as it is to a couple in the lower North Shore of Sydney? I don’t want a situation of genetic ‘haves and have-nots.’”

How to communicate the implications of the tests is another challenge.

“We need to make sure patients are absolutely clear on what the test is for and what their options are,” he says.

“One of the key drivers is getting this information into a digestible format that allows you to make a truly informed decision, especially if you’re vulnerable or disadvantaged or if English isn’t your first language or if you’re not used to dealing with the Australian medical system.”

Faunce says genetic counselling will need to be a critical component of the trial.

“You might be perfectly healthy and ready to settle down and start your family and then you get this test back showing a genetic marker, which might make the patient feel like there’s something wrong with them,” he says.

“It might be deleterious to the relationship and there could be adverse psychological consequences. It’s a complex and evolving area of medicine, one that genetic counsellors are trained to negotiate.”

Robson says discussions are already underway on these questions and others, as part of the trial.

“For example, we still need to sort out what genetic conditions to test for,” he says.

“Spinal muscular atrophy, cystic fibrosis and fragile X syndrome are relatively well-known, but there are literally hundreds of other conditions with a serious risk of ill health and death in children. Which ones do we pick?

“I don’t have all the answers, but if we can make these choices about our children’s future health and wellbeing available, acceptable and understandable to the whole country, that will be something unique in the history of the world.”

After Mackenzie died, aged seven months, Rachael wrote on her blog:

“Everything I hear now, I hear differently. Everything I see now, I see differently … The world has changed colour.”

And now, thanks to her, the world has changed for everyone else too.