Familial expansile osteolysis is an autosomal dominant bone dysplasia characterized by increased bone remodeling with osteolytic lesions mainly affecting the appendicular skeleton. There is medullary and cortical expansion of the bone without sclerosis, leading to painful and disabling deformities and tendency to pathologic fracture. Clinical features include onset of conductive hearing loss in childhood, premature loss of teeth, and variably increased serum alkaline phosphatase (summary by Palenzuela et al., 2002 and Elahi et al., 2007).