Nine-year-old Perth girl Tilly holds key to stamping out dementia after a miraculous world first trial success

Nine-year-old Perth girl Tilly is like any other child her age — with an interest in everything from netball to hair braiding and craft — except for one incredible, almost unbelievable aspect that has left the medical community in awe.

The bubbly Year 4 student was born with a rare gene mutation in her DNA and was diagnosed with childhood dementia, which carries a grim prognosis of a cruel, gradual cognitive decline before death, usually before turning 10.

So when her parents Kate and Lachlan Page were delivered the shattering news about their “rainbow baby” who was just three months old, their worst nightmare began to unfold.

“We had this beautiful baby, I have this man that I loved, life was good. And then it all just got taken away really quick,” Mrs Page told Sunday night’s 7NEWS Spotlight.

“I had this beautiful healthy baby, and they told me she was going to die.”

The parents, who before Tilly had lost a baby at 21 weeks, took a fortnight to grieve after being told all they could do was cherish the precious time they had left before their daughter would succumb to the incurable disease.

But after two weeks of sorrow, a surge of frustration hit Mrs Page.

“I pulled my socks up and went, ‘well that’s not good enough’,” she said.

That moment laid the foundation of a whirlwind nine months, during which time the parents discovered an experimental medical trial headed by Dr Nick Smith, the Head of Neurology at the Women’s and Children’s Hospital in Adelaide.

The trial could accommodate just 33 patients worldwide and only four children in Australia, but its exclusivity wasn’t the only barrier for Tilly.

Her mum and Dr Smith had to fight medical ethics authorities to allow Tilly to take part, because at one year old, she was deemed too young.

The family was ultimately successful with their pleas and Tilly was given the green light to participate as the youngest global candidate. But not before her parents were faced with more realisation of what the reality of her involvement would be.

“You have to sign off this paper that says, ‘are you willing for your child to die by taking this experimental drug?’. We looked at each other and said, ‘we are, because she’s going to anyway’,” Mrs Page said.

The revolutionary world-first gene therapy medicine was their best and only hope, and aged 12 months and two weeks, Tilly underwent the single-dose treatment, which was over in less than an hour.

“After all of that, it was the most anticlimactic thing,” her mum, who breastfed Tilly during the procedure, said.

The trial and the hope it offered the family was not available to Tilly’s uncle, Quinnton, who died 43 years ago from childhood dementia, two months before his 15th birthday.

Mr and Mrs Page had sought medical advice on the risk their child would have the disease, knowing the genetics runs in their family, and were told not to worry because only one of them was a carrier, not both.

The advice was proven wrong when an abnormality arose in Tilly’s tests, and a cross reference with Quinnton’s medical paperwork, that the hospital had held onto, confirmed that she was in fact born with the same gene mutation.

“I was devastated. My first grandchild, knowing at three months of age that she won’t have a future ... I felt like it was so unfair for Lachlan and Kate, for what they’re going to have to go through,” Tilly’s grandma, Margaret Page, said.

She was terrified Tilly would suffer the same fate as Quinnton, but the world first trial had offered a glimmer of hope.

Dr Smith explained the therapy works by inserting a good “working copy” gene that overrides the gene that causes the degeneration.

What happens next though, good or bad, is impossible to predict, with Mr and Mrs Page then left in an agonising waiting game.

To everyone’s amazement and joy, Tilly’s dementia never had a chance to dig its ugly claws in.

“In Tilly, dementia has not even eventuated. There was no evidence in Tilly, because of the time she was treated, that she even progressed to any cognitive deficit to any dementia at all,” Dr Smith said.

“Tilly kept hitting marks that children without the condition would keep hitting them, and that was the first stark evidence the therapy was working for her.”

Now, eight years later, her parents sit back and marvel at how “normal” she is.

“Tilly is happy, she is full of energy, she is just normal. It’s her averageness that we love the most,” Mrs Page said.

“She is just miraculous in her averageness.”

It’s hoped Tilly’s successful trial will open critical doors for the thousands of other children born with childhood dementia and help researchers unlock the key in finding a cure for dementia in adults.

In the meantime though, the treatment is not available and its expected it could be several years before its accessible to people who desperately need it.

Experts speculate that one day, a vaccine could be available at birth to stamp out dementia entirely.