3-year-old Osama Hamad has Niemann Pick Type C, which affects his body's ability to transport cholesterol.
The cholesterol accumulates in tissues, like the brain, where it can cause dementia, including difficulty with learning and short-term memory.
Osama could literally forget how to walk or talk, but the new drug gets the cholesterol moving.
"It works like Febreeze. The medicine goes in and it grabs the cholesterol and it brings it down and helps it flush out of the body," said Osama's mother Deanna.
Osama's parents say he's doing things they never thought he could.
But every day is filled with worry that he'll regress, or the drug won't be available to them anymore.
"We do worry every night what will happen," said Deanna.
"Sometimes I just want to forget about it or just to ignore it," said the boy's father, also named Osama.
The Hamads are now lobbying the FDA to approve the drug so he can keep taking it.
"I'm definitely more optimistic now. He'll get through it, he'll fight his way and we will find him a cure," said Deanna.