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What is OI?

Osteogenesis Imperfecta (OI), or brittle bone disease, is a group of genetic disorders caused mainly by >1,350 different dominant and >150 recessive mutations. One child among 10-20,000 is born with OI and mutations in the collagen genes resulting in abnormal collagen microfibril assembly are most common.


The major clinical manifestations are atypical skeletal development, osteopenia (a medical condition in which the protein and mineral content of bone tissue is reduced), multiple painful fractures and short stature, but OI individuals also suffer from brittle teeth, hearing loss and hypermobile joints and have a higher risk of heart valve insufficiency, aneurysms and bleeding and coagulation deficiencies throughout their life time.


OI has a diversity of clinical presentation, ranging from the mild type I that only becomes evident in adulthood to the perinatally lethal type IIA/C. Type III OI is the most severe form that is compatible with survival into adulthood. Individuals affected by OI type III may experience hundreds of fractures in a lifetime. However, most commonly OI presents in childhood with multiple fractures after little or no trauma (type I/IV). Type IV and V OI can be moderately severe, but are very variable. Life expectancy is not affected in milder OI types but may be shortened for those with more severe types.


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