Osteogenesis imperfecta means “imperfect bone formation” and is commonly known as “brittle bone disease” or OI. It is a rare genetic disorder that affects the protein collagen, which is found in bone, teeth, skin, tendons, and parts of the eye. People with osteogenesis imperfecta have bones that can break easily, sometimes with no obvious cause. NICHD research has been instrumental in discovering the genes that cause some types of OI. The institute continues to conduct and support research on many aspects of OI, including genetics and treatment.