Osteogenesis Imperfecta (OI) is a genetic bone disorder in which bones break easily. This congenital bone fragility is also known as brittle bone disease or "Lobstein syndrome".

People with OI are born with defective connective tissue, or without the ability to make it.   Sometimes the bones break for no known reason. OI can also cause weak muscles, brittle teeth, a curved spine and hearing loss. OI can range from mild to severe and symptoms vary from person to person.