Twins battle one-in-two-million condition that is turning them to stone

Meet the twins battling a one-in-two-million condition that is slowly turning their muscles to bone.

Lucy and Zoe, from Northern Ireland, were both born with fibrodysplasia ossificans progressiva (FOP).

The condition, which is so rare that the sisters are one of just three sets of twins in the world known to have it, causes muscle tissues and tendons to be replaced by bone, growing outside the skeleton.

As adults, they have become more affected by the condition - with Zoe, who now requires a walker or wheelchair to get around, particularly impacted.

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