The walls of the O’Neill house in Columbia do talk.

They’re covered with phrases 7-year-old Eliza used to rattle off when she could still speak and the scribbles she and her older brother made when she could still color with crayons.

An uncertain future awaits Eliza, whose family isolated themselves for two years, mostly in their house with the talking walls, to protect her immune system and give her a chance at life.

An uncertain future is a good thing for Eliza O’Neill, her father says, because for most children like her, the future is certain – and it’s not bright.

Nearly a year ago, Eliza became the first child in the world to receive a clinical gene therapy treatment for Sanfilippo syndrome, a rare, degenerative genetic disease that causes severe disability, irreversible brain damage and, typically, death before adulthood.

“We have no false belief that this is a magic medicine that’s going to turn back the clock and make her progress like normal,” said Glenn O’Neill, Eliza’s father. Sanfilippo “impacts these kids so quickly. It’s literally a rapid, childhood Alzheimer’s.”

In the four years since the disease began to show its signs in their daughter, it “has really taken away a lot from Eliza,” said her mother, Cara O’Neill. “She used to speak to us in sentences and sing songs, and retell us stories from books and videos, and know her ABCs, and count to 20 and all the typical things preschool kids can do.”

She believes her daughter still has those skills inside her and hopes to see them return one day.

But the O’Neills’ hope goes beyond slowing the progression of the disease in Eliza.

“Ten years from now, hopefully sooner, we’ll have newborn screening and have a proven treatment or cure,” Glenn O’Neill said. “To think, you could take away this pain very early (in a child’s life).”

That’s why they continue to raise money through their Cure Sanfilippo Foundation for continued research and future treatment trials. They’ve raised $4 million in three years. A 5K run/walk fundraiser Saturday in Columbia will be the first fundraising event in about three years that Eliza has attended herself.

The O’Neills shut themselves off from most of the outside world for 726 days from 2014-2016 to protect Eliza from being exposed to a virus that could have derailed her chances to be accepted for the gene therapy trial.

Eliza received the one-time treatment last May in Columbus, Ohio. The O’Neills were able to end their isolation. And they’ve seen Eliza’s quality of life and demeanor improved, her parents say. They’re cautiously optimistic for her future.

“We hope perhaps she can regain some of the skills she’s lost,” Glenn O’Neill said.

They miss her voice. When she was still speaking, the family took to writing phrases she said on the walls of their kitchen, with dates. There are none from 2017.

She can’t sing along with the songs the family used to sing together, but her eyes still light up when she hears music.

“She’s still running. She’s still climbing up in her playhouse. She loves looking through her books. She loves Dora the Explorer,” Glenn O’Neill said. “We cherish every second because we know none of us are guaranteed a future. And we feel blessed we’ve been given this chance of potentially not going down the regular path of Sanfilippo.”

They’re also still hopeful that through their foundation work, they can help other families get that chance, too.

“It’s heart-wrenching,” Glenn O’Neill said. “Everyone wants the fairy tale. No one wants the fairy tale more than us. ... But just because it’s not a fairy tale doesn’t mean good can’t come out of it.”