'He'll never be able to do what daddy did,' Hunter's Hall of Fame father Jim Kelly said last year. 'But he's going to do greater things. He's going to make a difference in kids' lives. He already has.'

"Our prayers go to the family and kids," Jim Kelly's brother, Dan, told The Associated Press.

Born in 1997, Hunter Kelly was given no more than three years to live after being diagnosed with Krabbe Disease, an inherited degenerative disorder of the central and peripheral nervous systems.

The disease hinders development of the myelin sheath, a fatty covering that protects the brain's nerve fibers.

No Known Cure

In honor of their son, Jim Kelly and his wife, Jill, established the Hunter's Hope Foundation in 1997, which has raised more than $6 million and awarded more than $3.8 million to leukodystrophy and other neurological disease-related research.

The disease has no known cure.

Jim Kelly, who won an unprecedented four straight AFC titles as the Bills' quarterback in the early 1990s, had credited his son for serving as his inspiration after he retired from football following the 1996 season.

"He'll never be able to do what daddy did," Kelly said last year. "But he's going to do greater things. He's going to make a difference in kids' lives. He already has."

Kelly and his son happened to share the same birthday, Valentine's Day.

The Kelly family was preparing to issue a press release later in the day, Dan Kelly said.