Osteogenesis Imperfecta

Osteogenesis imperfecta (OI) is a genetic disorder affecting type I collagen synthesis or structure, resulting in defective bone matrix and severe bone fragility. Type I collagen constitutes approximately 90% of bone organic matrix; defects cause profound bone quality and quantity abnormalities, leading to propensity for fractures with minimal trauma. Severity varies greatly: Type I (mild) features normal height, blue sclera, and fractures beginning in childhood; Type II (perinatally lethal) features severe skeletal deformities and intrauterine or early postnatal death; Type III (progressive) features severe skeletal deformities, growth retardation, and progressive disabilities; Type IV features variable severity. Fractures typically increase during growth and activity periods, with some improvement after skeletal maturity. Beyond skeletal manifestations, patients commonly develop progressive conductive or sensorineural hearing loss (50% by age 30), dental problems from enamel defects, cardiac valve abnormalities, and blue or gray sclera due to increased collagen transparency.