Safety of Fresolimumab in the Treatment of Osteogenesis Imperfecta

The purpose of this study is to determine if fresolimumab is safe as a treatment for OI. We will evaluate the safety of a single dose of fresolimumab in the 1st stage of the study. We will evaluate the safety of multiple doses of fresolimumab in the 2nd stage of the study. The Investigators will evaluate the effect of the two doses of fresolimumab in Stage 1 on markers of bone turnover and determine the dose that shows the greatest reduction in bone turnover markers compared to no treatment. This dose will be chosen for the repeat dose studies. If there were no significant changes between the bone turnover markers with either dose, the 4 mg/kg dose will be chosen for the repeat dose study.