Osteogenesis imperfecta

Osteogenesis imperfecta (OI), commonly known as 'brittle bone disease,' is a group of genetic disorders primarily affecting the bones and connective tissues. The condition is characterized by bones that break easily, often with little or no apparent cause. OI is caused most frequently by mutations in the COL1A1 or COL1A2 genes, which encode the chains of type I collagen — the major structural protein of bone, skin, tendons, and other connective tissues. However, mutations in numerous other genes involved in collagen processing, bone mineralization, and osteoblast function have also been identified, leading to both autosomal dominant and autosomal recessive forms of the disease. The clinical severity of OI varies enormously, ranging from mild forms with few fractures and near-normal stature (Type I) to perinatally lethal forms with severe skeletal deformities (Type II). Key symptoms include increased bone fragility and recurrent fractures, blue or gray sclerae (the whites of the eyes), short stature, progressive skeletal deformities such as bowing of the long bones and scoliosis, dentinogenesis imperfecta (brittle, discolored teeth), hearing loss that may develop in adolescence or adulthood, joint hypermobility, and easy bruising. The Sillence classification system traditionally divides OI into four main types (I through IV), though additional genetic subtypes are now recognized. There is currently no cure for osteogenesis imperfecta, but management is multidisciplinary and aims to minimize fractures, maximize mobility, and improve quality of life. Bisphosphonates (such as pamidronate and zoledronic acid) are widely used to increase bone density and reduce fracture rates, particularly in moderate to severe forms. Orthopedic interventions, including intramedullary rodding surgery to stabilize long bones, are frequently employed. Physical therapy and rehabilitation are essential components of care. Emerging therapies under investigation include anti-sclerostin antibodies, anti-RANKL antibodies (denosumab), and gene-based approaches. Regular monitoring by a team including geneticists, orthopedic surgeons, endocrinologists, audiologists, and dentists is recommended.

Data sourced from FDA regulatory filings and ClinicalTrials.gov. Updated periodically.

Common questions about Osteogenesis imperfecta