SOUTHPORT, Conn. (WTNH) – “He loves running around and being silly, he loves to laugh,” says Mike Dwyer of his son, Jack, who recently celebrated two milestones.

He started kindergarten and became the first child in the United States to receive a new gene therapy to treat SPG50, an extremely rare, degenerative genetic disorder that affects only about 87 children worldwide.

“We agonized over the decision because it’s a clinical trial, there are no guarantees,” says Jack’s mom, Devin. “But, we saw Jack declining and we saw him potentially losing the ability to walk which is terrifying.”

The Dwyers believe the therapy is their son’s only hope to fight this disease that causes cognitive and physical decline.

Jack received a single lumbar puncture at a children’s hospital in Texas and will now be monitored for years.

Doctors hope the five-year-old starts to produce the protein that his body is missing, halting the disease.

“We’re cautiously optimistic,” says Devin. “He’s progressing cognitively, he’s not declining from a physical standpoint like he was before.”

All told, the treatment costs an astounding $450,000 per patient. So, the Dwyers started Jack’s Corner Foundation to help their son and others.

“We’re hoping to raise more money so that more kids can get treated,” says Devin.

In many ways, Jack is a typical little boy.

“Trucks are top of the list. Anytime there’s a construction site, he wants to get out and look at them,” says Mike with a smile.

But the bravery displayed by him – and his parents – may just set a new course for a devastating disease.

“He deserves to live an independent life, to go to college. He deserves every chance in the world and my hope is that the very scary choice we made gives him those opportunities,” says Devin.

The family is hosting a fundraising event on Saturday night.

A Night in Jack’s Corner will include food trucks, lawn games, a silent auction and music.