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CASTLE ROCK, Colo. — Caleb Burgess loves baseball and just being a kid like any other active 11 year old — except for a rare diagnosis.

“Fibrodysplasia Ossificans Progressiva,” his mom, Stephanie Burgess, explained.

It’s known as FOP, a disease so uncommon it took several doctors and one of the world’s leading researchers to diagnose Caleb.

When he was 7 years old, his mom noticed Caleb was losing mobility in his neck.

“We started researching … came up with FOP and, even though it was super rare, all of his symptoms and signs seemed to point to that,” she said.

But it took his Castle Rock family three years to have him diagnosed.

“It turns soft tissue muscles, ligaments, joints and cartilage into bone, said Caleb’s dad Scott. “And it essentially creates a second skeleton over the existing skeleton that imprisons the body.”

Caleb’s family and Raptors Athletics Baseball organized a home run derby in Douglas County July 15 to help Caleb and four other kids in Colorado diagnosed with FOP.

The disease is a genetic mutation and doctors don’t know what triggers it.  There’s no cure, no real known treatment there are only 800 people in the world known to have it.

“When he started to grow more bones in his knees after baseball one season I just kept pushing until they did more X-rays,” Stephanie said.

Flare ups can be sparked by illness, injury or no reason at all — and are treated with five days of anti-inflammatory steroids.

Caleb says it causes a lot of pain.

“Usually really sore, sometimes I just have to ice,” he said. “It’s really tough but my friends always have my back.”

In fact, one year to the day after his diagnosis in June, Caleb got a walk-off hit to lead his team to their league championship.

No one can say how the disease will progress.

“So we let him do whatever he can do while he can do it,” his mom said.

And they’ll continue in the fight to find a cure.

“It has been truly heartwarming to see people get behind a cause,” Caleb’s dad said.

They were hoping to raise $20,000 to fund research with their event.

If you’d like to donate or learn more about FOP visit this website.