The parents of Eliza O’Neill, the little girl with an incurable and deadly brain disorder, are making one final desperate push to raise funds for the clinical trial that will test a gene therapy for the disease—and perhaps offer hope for Eliza.

The O’Neills have already raised $1.3 million through a viral video and hope that by Eliza’s fifth birthday on Sunday they’ll hit their $1.8 million goal.
While there is no guarantee that Eliza will be among those chosen to participate in the trial, which could start sometime in the middle of 2015, its organizers say that at this point there is no reason that she wouldn’t qualify.
Over the past year, the O’Neills have tried to focus on aspects of life over which they have some control, such as helping to make the trial a reality and keeping their daughter as healthy as possible. Sometimes, they even allow themselves to think about what life might be like if Eliza was helped by the experimental medication.
“Our hopes are for Eliza to have a life, and a good life,” said her dad, Glenn O’Neill. “I sometimes let my mind go to places of future birthdays and her dating and getting married.”

It was just two years ago that Eliza was diagnosed with Sanfilippo syndrome, an inherited disease that destroys brain cells and kills its young victims before they are out of their teens.
The O’Neills turned to the Internet to learn more about the disease and while most of what they read was disheartening, there was a glimmer of hope: Nationwide Children’s Hospital researchers had developed a gene therapy that appeared to cure the disease, but so far only in mice.
Children with Sanfilippo Syndrome are born with two copies of a faulty gene. Normally, the gene makes an enzyme that breaks down glycosaminoglycans, or GAGs, which are long chains of sugar molecules that are the glue that holds cells together. Without the enzyme, GAGs buildup inside the cells gunking everything up and eventually killing them.

The fix developed by researchers at Nationwide was to attach functioning copies of the gene to a harmless virus which would then be injected into a patient. The virus would enter the brain and then “infect” cells with working copies of the gene.
In mouse experiments, the treatment delivered enough correct copies of the gene to fix the damage, said Douglas McCarty, a principal investigator at Nationwide’s Research and an associate professor of pediatrics at Ohio State University College of Medicine.
While the mouse experiments offered hope, there was a major barrier to getting help for Eliza and other kids like her: a clinical trial would cost nearly $2.5 million.
Fundraising would give the O’Neills some sense of control over their out-of-control lives and also push the possibility of a therapy for Eliza a bit closer.
Now, with Eliza’s fifth birthday just days away and over $1 million raised, the clinical trial is almost a reality. Researchers just have to iron out some details on how to efficiently produce enough of the medication to treat patients and finish up the toxicity studies needed to get Food and Drug Administration approval.
“If all goes well, I think it would be realistic to say that by the middle of 2015 we could be doing the first gene transfer in a human patient,” said Dr. Kevin Flanigan, a principal investigator at The Research Institute at Nationwide Children’s Hospital and a professor of neurology at the Ohio State University College of Medicine.
It’s still up in the air, however, whether Eliza will be included in that trial. And until the process is further along, patients won’t be chosen, the researchers said.
Still, “there is no reason to expect that Eliza would not be a good candidate for this trial,” Flanigan said. “At the same time, I want to point out that no one has been selected yet.”

For the O’Neills, time is crucial. They are hoping that the trial will start before the disease does so much damage that Eliza can’t be helped. Though she has ceased to hit new milestones, the bubbly little girl hasn’t lost any ground yet, O’Neill said. “She’s holding her own,” he added. “She still is talking and understanding. She still has an imagination.”
Another issue that won’t be resolved until there is a working therapy is whether kids’ brains can rewire around damaged cells once the disease has been halted. “We would hope that by removing the ongoing insult to the brain, that might allow some degree of recovery,” Flanigan said. “Even though that is our hope, it’s not something we can promise.”
To expect recovery of lost functions might be overly optimistic, said Dr. Maria Escolar, a professor of pediatrics and director of the program for neurodevelopment of rare disorders at the Children’s Hospital of Pittsburgh at the University of Pittsburgh Medical Center.
“In the first three years of life the brain is growing more than at any other time,” Escolar said. “Any insult during that time — and this is a huge insult— will have a much worse outcome than it would in an adult. I think it will be very unlikely that they will be able to function as a normal adult.”
For parents of kids with Sanfilippo, it might be enough just to stop the disease.
“Many parents have shared with us that they would be happy with something that interrupts the progression of this devastating disease at whatever stage we could interrupt it at,” Flanigan said.
In the end, there isn’t even a guarantee that the therapy will work in children. Over the years there have been plenty of treatments that cured diseases in mice but did nothing in humans.
"We realize so many things have to go just right for this to work," O'Neill said. "But we have hope. What else do we have if we don't have hope?"
Linda Carroll is a regular contributor to NBCNews.com and TODAY.com. She is co-author of "The Concussion Crisis: Anatomy of a Silent Epidemic” and the recently published “Duel for the Crown: Affirmed, Alydar, and Racing’s Greatest Rivalry”