Spinal muscular atrophy: New hope for Australian parents of SMA infants
Updated
Bethan and Johnny McElwee's daughter Aviana was just a few months old when a Darwin paediatrician queried the behaviour behind her nickname, Little Miss Froggy.
"I was calling her [that] because she was sitting a bit like a frog," Ms McElwee said.
"She's such a relaxed and chilled baby that we always just thought she was chilling. When you've never had a baby before, you don't know what to look for.
"Our paediatrician thought she might have a hip problem."
But a hip scan came back clear.
It was a follow up blood test that revealed an anomaly in Aviana's genes — a rare and little-known disease that, at its most ruthless, will kill an infant before age two.
Called spinal muscular atrophy (SMA), the genetic disorder wastes away the nerves that control muscle movement, leading to progressive paralysis followed by weakness in breathing and swallowing.
Aviana turned out to have the most severe form, SMA type 1.
"In a nutshell, when we got the diagnosis, the [specialist] said: 'We have no cure and they generally don't live to see their first birthday. They can sometimes see their second'," Ms McElwee said.
"That was all he could tell us and it was a huge shock. It was the end of our world. It all came crashing down that day."
Lack of cure leaves parents feeling helpless
Only one in 10,000 babies are thought to be born with SMA each year worldwide.
Few parents know they are silent carriers of the recessive gene until symptoms like floppiness start to present in their children, and there is currently no routine testing of newborns for SMA in Australia.
Yet it is the leading genetic cause of infant death, according to Michelle Farrar, a leading SMA expert and neurologist at Sydney Children's Hospital.
"I think most people haven't heard of it just because it is so severe and so devastating," Dr Farrar said.
Those with less severe and later-onset forms can have promising outcomes and even normal life expectancies, however most SMA type 1 infants require feeding tubes and breathing machines soon after diagnosis; the treatment is essentially palliative.
"Generally most parents are looking at quality of life rather than prolonging life in such a severe situation. We hear a lot about bucket lists," Dr Farrar said.
It was a sentiment reiterated by Aviana's paediatric neurologist, Hugo Sampaio, who sees several new cases of SMA type 1 annually in his role at Sydney Children's Hospital.
"The main thing you hear from parents is grief and dealing with a child that is fading away," Dr Sampaio said.
"It's a feeling of total helplessness."
Yet after many years, there is some hope on the horizon.
Aviana takes part in promising drug program
Developed internationally, a new treatment called nusinersen is producing promising results, with 40 per cent of babies in a recent blind trial of various SMA types reaching milestones such as sitting, crawling and walking.
None of the babies that received a placebo drug during that trial reached those milestones, The New York Times reported this month.
Two months ago Aviana became the ninth baby with SMA type 1 in the world to be given the drug for free as part of an Expanded Access Program (EAP).
"That means the company is supplying the drug for free to the patients and hospitals while regulatory approvals are being sought for the drug, so it can be on market as an approved therapy," Dr Farrar explained.
"These children don't have time to wait for that process to happen."
Injections cost $US125,000
Nusinersen works by enabling a backup gene to produce a protein that supports motor neurons, the underlying deficiency in SMA patients that leads muscles to atrophy.
It is injected into the spinal fluid in a manner similar to receiving an epidural, with patients likely to require these injections several times a year for life.
"An injection is really nothing to keep her here," Ms McElwee said.
While circumspect about the drug's effects until more is known, the McElwees believe it is helping with Aviana's mobility.
Dr Sampaio was less restrained about his patient's progress; he said he was "confident" that what he was seeing was due to the "ground-breaking" treatment.
"What I've seen is no decline. If anything, she's actually getting stronger, which is totally against the course of SMA," he said.
"I'm actually quite astonished."
Last month, in a nod to mid-trial results, the United States Food and Drug Administration (FDA) approved the drug for all SMA patients.
But the news was soon overshadowed by the drug company's cost announcement — $US125,000 a dose.
Dr Sampaio said he did not want to diminish the local SMA community's current "hope and optimism" by speculating on nusinersen's Australian price tag, although he added it would "come at a cost because it's been a decade in the making".
It is unclear when or if the drug will be approved in Australia, while it is also unclear if it will receive Pharmaceuticals Benefits Scheme (PBS) status.
Dr Sampaio added that some local parents had declined to take part in the trials because of the drug's side effects and ethical concerns about prolonging the life of severely disabled children.
Nusinersen is not billed as a cure for SMA, with the body unable to regrow motor neurons damaged before treatment has commenced.
"Aviana is still weak and I doesn't have normal muscle function and I don't know if she ever will. I still worry that Aviana will die of SMA-related complications," Dr Sampaio said.
Calls to bring in pre-pregnancy testing
Dr Farrar said nusinersen so far seemed "amazing", however she issued a word of caution.
"I think there's hope but there's also hype," she said.
"We just need to wait until we know the full facts rather than get carried away with the hype and then be in a situation where it's not exactly what we expected. But it's so wonderful to have hope for the first time."
Dr Farrar said the next step in Australia was awareness raising.
"It's a really rare disease and most doctors have never seen it in their entire career," she said.
"So it's really important that awareness is raised so parents don't get in this situation where they've been on this diagnostic odyssey for several months, and then they realise there was a treatment they could have had, and now it's too late and there's damage."
For the McElwees, the last three months has been a rollercoaster of shock, grief and hope.
"I just feel like we have to keep going for Aviana," Ms McElwee said.
"She's just wonderful and a little ray of sunshine. She's very relaxed, very sociable and loves the pub. She loves being around people."
The couple said they would now turn their attention to lobbying for newborn testing for SMA and pre-birth genetic testing for potential carriers of the SMA gene, so that fewer parents have to go through their experience.
"It might not be curable but it's 100 per cent preventable," Mr McElwee said.
"I would like to see a world where all women when they turned 18 were tested for this gene so they can know if they're a carrier."
Topics: genetic-disorders, infant-health, babies---newborns, parenting, medical-research, motor-neurone-disease, neuroscience, family, darwin-0800, sydney-2000
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