SERPINF1 and osteogenesis imperfecta: In accordance with this hypothesis, there is some evidence of increased bone resorption in these patients.14 If loss of PEDF resulted only in an increase in the number of mature osteoclasts, one would expect bisphosphonate therapy to be beneficial in disease management.19 However, OI type VI patients do not appear to respond as well as other OI patients to bisphosphonate therapy, suggesting that PEDF may have additional functions in maintaining bone homeostasis, specifically in the regulation of osteoid mineralization.13