Osteogenesis Imperfecta is a genetic condition which causes extremely fragile bones. The severity of OI depends on the specific gene defect. All people with OI have weak bones, which makes them susceptible to fractures. The classic symptoms include blue tint to the white of their eyes, multiple bone fractures, early hearing loss. People with OI often have loose joints and flat feet.
Osteogenesis imperfecta. Genetics Home Reference. https://ghr.nlm.nih.gov/condition/osteogenesis-imperfecta