To assess the binding between aptscl56 and FL SOST in human serum from the above OI patients and healthy controls, aptscl56 or aptscl56m was immobilized on magnetic beads and then untreated or pretreated with wild-type loop3 and wild-type loop2, respectively, followed by incubation with the serum. This evidence concerns the gene SOST and osteogenesis imperfecta.