Osteogenesis imperfecta is a hereditary disorder characterized by bone fragility and often severe deformities. Osteogenesis imperfecta exhibits a variety of clinical presentations ranging from intrauterine death at one end of the spectrum to normal growth and low fracture incidence at the other depending on the severity. Affected children and adults suffer from chronic pain, decreased mobility short stature, recurrent and multiple bone fractures requiring hospitalisation and surgery, and often irreversible deformities.
The main causes of OI are defects in the structure or synthesis of type I collagen. The severity of the condition varies from mild to lethal. Type II OI is the most severe form of the disease resulting in death in the perinatal period, with patients rarely surviving for more than a few days. Type III OI is the most severe form of the disease compatible with survival past the perinatal period. OI type III is rarely diagnosed before 18 weeks of pregnancy on ultrasound and requires sequential ultrasounds. The severe progressive skeletal deformity may begin at birth. Multiple fractures may be present at birth and frequent fractures occur thereafter because of the very fragile bones. The high fracture rate continues into adult life. The children have marked short stature and are frequently wheelchair bound. While type IV can vary from severe to mild, with the more severely affected patients presenting with fractures at birth, suffering moderate skeletal deformity and attaining a relatively short stature.