Question: what is the rarest syndrome ?

Hayley Moulding answered on 16 Mar 2016:

Great question. I know about some of the rarest syndromes. They are all very different though and they all have really really long names. Fibrodysplasia ossificans progressive is one – it is a disorder where your connective tissue, so ligaments and tendons turn into bone. It is a very very painful disorder. If you fell over and hurt yourself, that areas which was damaged would form a scab. In someone with the syndrome, instead this area would turn into bone inside their body.