Fibrodysplasia Ossificans Progressiva (FOP), present in approximately 1 in million people, is a genetic disorder in which muscle tissue, ligaments, and tendons are gradually replaced with bone. Over time this can cause serious issues with mobility, speaking, and even eating. Some people with the disease suffer from malnutrition due to their difficulties with eating. This disease can also affect the person's breathing as there can be extra bone that forms around the rib cage.