What You Need To Know About The Rare Condition Turning These Sisters To Stone

Twin sisters Lucy Fretwell and Zoe Buxton both suffer from a condition that affects only one in two million people, and is slowly turning their bodies to stone.

Fibrodysplasia ossificans progressiva (FOP) is an extremely rare genetic condition that causes muscle tissue, tendons, and ligaments to be replaced by bone, according to the National Institutes of Health. The condition is usually noticeable in childhood, and starts at the neck and shoulders.

Fretwell and Buxton were both born with bony lumps on their toes, which is a sign of FOP, but doctors didn't notice it, the twins told Metro. It wasn't until Buxton fell off a couch when she was five-years-old and broke her elbow that the twins and their parents realized something was wrong.

"We thought it was a normal injury until the cast came off and I couldn’t straighten my arm – it was agony if I tried," Buxton told Metro.

As can happen with severe injuries in people with FOP, the muscle surrounding Buxton's injured elbow had ossified and turned to bone. An injury to her neck when she was 11 did the same to Fretwell, who can no longer raise her arms over her head. Buxton also suffered a second ossification when she was 11 and broke her leg after falling off of a scooter.

Although Buxton is able to use crutches or a wheelchair to get around now, both she and Fretwell are likely to lose more mobility over time.

People with FOP sometimes develop extra bone growth around the rib cage, which causes difficulties breathing, and may be unable to fully open their mouths and therefore struggle to eat, according to the NIH.

Still, Fretwell and Buxton don't let this get them down. They're both still young (only 26), and looking forward to the future. They're currently in clinical trials for a new drug that may help their condition, and both are looking forward to motherhood. Buxton and her husband are considering having a child, and Fretwell is looking to adopt with her fiancé.

"It’s early days, and our injuries are irreversible," Buxton told Metro. "But we’re so positive about the future, and we refuse to let our condition stop us from living life to the full."