Multicenter,Single-arm Study to Evaluate Efficacy, Safety, & Pharmacokinetics of Denosumab in Children w/ OI

• Eligibility criteria relates to initial enrollment into this study (6-Month Dosing Regimen). Subjects reconsenting to a 3-Month Dosing Regimen will not repeat eligibility assessments Inclusion Criteria: • Clinical diagnosis of OI defined as a clinical history consistent with type I-IV OI Clinical severity of OI as defined by 2 or more prevalent vertebral compression fractures; OR1 prevalent vertebral compression fracture and 1 or more nonvertebral fractures within the previous 2 years; OR 3 or more fractures within the previous 2 years. Exclusion Criteria: * Inability or unwillingness to comply with the requirements for frequent calcium and phosphorus monitoring for 14 days after the first dose of denosumab (only applies to the first 5 subjects age 11 to17 enrolled in the study and the first 5 subjects of any age meeting the criteria for increased bone turnover * Currently unhealed fracture or osteotomy as defined by orthopedic opinion * Osteotomy within 5 months of screening * Evidence of untreated oral cavities or oral infections * Recent or planned invasive dental procedure * Surgical tooth extraction which has not healed by screening * History of an electrophoresis pattern inconsistent with type I to IV OI * History of genetic testing results inconsistent with type I to IV OI * Abnormalities of the following per central laboratory reference ranges at screening: Serum albumin corrected calcium \< lower limit of normal (LLN) Serum vitamin D \< 20 ng/mL; re-screening f…