Skeletal dysplasias are a large, heterogeneous group of rare, usually monogenic disorders that affect skeletal development. Fibrodysplasia ossificans progressiva (FOP), osteogenesis imperfecta type V (OIV) and the carpotarsal osteolysis syndromes (multicentric carpotarsal osteolysis (MCTO); multicentric osteolysis nodulosis and arthropathy (MONA); and Winchester syndrome) are disparate disorders that illustrate a spectrum of abnormal ossification in skeletal dysplasias. FOP is characterised by disabling heterotopic ossification. New therapeutic developments are giving hope to those affected by this debilitating disorder. Understanding the pathophysiology behind OIV and the carpotarsal osteolysis syndromes may similarly improve the prospects for affected individuals. Individuals with OIV develop calcification of the interosseous membranes, and have a propensity to form hyperplastic callus following fracture. The carpotarsal osteolysis syndromes are characterised by progressive carpal and tarsal bone loss, assumed to be due to osteoclast-mediated resorption. However, our data suggest abnormalities in sub-articular endochondral ossification may explain the phenotype.