FOP

Fibrodysplasia ossificans progressiva (FOP) (/ˌfaɪbroʊdɪˈspleɪʒə ɑˈsɪfəˌkænz prəˈgrɛsəvə/) is an extremely rare connective tissue disease. It is a severe, disabling disease with no cure or treatment and is the only known medical condition where one organ system changes into another.