1
4]. Related to the OI story, the serpins, proteins which regulate protease activities, are IDPs, and serpin F1 mutations are associated with type V OI [153]. Another possible example of defective IDPs leading to bone disease is osteoporosis which has been associated with defects in osteonectin [156], which, as noted above has IDP regions. Osteopontin deficiency results in dystrophic calcification