Lorenzo Andrade-Cruz, 8, has ALD, a genetic condition that affects the brain.
More info on ALD.
The Pennsylvania-based nonprofit, Jamie's Dream Team, is seeking donations and volunteers to help build his dream tree house.
Though Lorenzo doesn't have symptoms now, that is likely to change.
"You stop walking," he said. "You stop chewing. And you stop talking."
The disorder took both of his brothers' lives. Jonathan died at the age of 11 in 2017 and 15-year-old Christian died in May.
Their deaths took a toll on the family.
"Really hard for me," Lorenzo said.
His mother, Noborina Cruz-Ponce, has hope but said there's no cure for ALD.
"There's no way to prepare him because it's very difficult," Cruz-Ponce said in Spanish.
She wants to make his life the best she can. That's why the tree house means so much.
"It'd be his space for him to play, where he can distract himself, where he can be happy," she said.
His younger sister, who does not have the disease, looks forward to joining Lorenzo in the tree house.
"It's going to be fun and we can play in it," said 6-year-old Gloria Ortiz-Cruz, 6.
Lorenzo can't wait for the day his tree house is built.
"I will explode," he said happily.
But before that happens, the organization needs to raise money. They're hoping a contractor will take the lead on planning and building the tree house.
Want to help? Click here to donate.