Twin sisters from Northern Ireland are suffering from a rare genetic disorder that is slowly and gradually turning them into stone.According to a report in the Daily Mail, only three pairs of twins in the entire world suffer from the disorder and 26-year-old Zoe Buxton and Lucy Fretwell are one of them.Called fibrodysplasia ossificans progressiva (FOP), the disorder causes bone to replace the muscles and tendons.

  The report also listed a few facts about the disease:

FOP is a rare inherited disorder and worsens over time.
Causes bone to arise in muscle, ligaments and tendons.
Those with it have shortened big toes at birth.
FOP causes swelling and makes it challenging to eat if the jaw is affected.
Suffers have limited movement.
While there is no cure, treatment helps relieve pain.
Despite their condition and knowing what lies in store, the twins are pretty strong and are even considering having children undeterred by the fact that there is a high risk of the problem being passed on to their offspring.

Currently they are participating in a trial for a new drug that could help their condition, the report said.