Osteogenesis imperfecta is a group of inherited disorders that mainly affect the bones, causing them to be fragile and easily broken. Type III is a severe form of the disorder; its signs and symptoms fall between the very severe osteogenesis imperfecta type II and the milder osteogenesis imperfecta type I. Osteogenesis imperfecta, type III is a subtype of osteogenesis imperfecta. Infants with this form of osteogenesis imperfecta have soft, fragile bones that fracture easily. Broken bones may occur even before birth. People with the disorder are much shorter than average (adult height ranges from just under 3 feet to about 4 feet) because the condition prevents bones from growing normally. Spinal curvature (scoliosis) and bone abnormalities often become progressively worse during childhood, but tend to stabilize during adolescence. These complications may shorten a person's lifespan by affecting heart and lung function. Other signs and symptoms include a light blue tint to the part of the eyeball that is usually white (the sclera), brittle and discolored teeth, loose joints, and, in some cases, hearing loss.