Osteogenesis imperfecta and Paget's disease of bone. Biochemical and morphologic studies.

Osteogenesis imperfecta (OI) and Paget's disease of bone occurred in a patient whose brother has Paget's disease. Several other relatives have the dominant variety of OI. The familial occurrence of the two diseases is presumably due to chance and, to our knowledge, has not been previously reported. Examination of iliac crest bone biopsy specimens showed mild changes of both diseases in the proband. Electron microscopy of the bone collagen demonstrated type I collagen fibers, which are reduced in number, decreased in diameter, and stellate rather than smooth in outline. Three populations of collagen fibers were observed in the bone. The synthesis of type I collagen by dermal fibroblasts was diminished in the proband and affected relatives, but it was normal in the unaffected relatives. Since collagen fibers with a stellate outline have not been observed in OI bone, an intriguing question is the effect to the putative Paget agent (? viral) on collagen synthesis in OI.