Osteogenesis imperfecta: a registry-based study of the clinical symptoms of disease in a large cohort of Italian patients.

Introduction: Osteogenesis imperfecta (OI) is a rare, heritable, skeletal disorder resulting in defective bone formation. Clinical presentation is heterogeneous. This study aims to provide an overview of the clinical manifestations by disease severity and age in a large cohort of Italian patients with OI. Methods: Patients with OI who received care at the IRCCS Istituto Ortopedico Rizzoli from 2005 to 2024 were enrolled in the Registry of Osteogenesis Imperfecta database and analyzed for this study. Results: Overall, 628 patients with OI were included in the study (51.1% had Type I, 5.1% Type III, 6.7% Type IV, 0.3% Type V, and 36.8% unknown type). Patient height was reduced with increasing disease severity (Type I had mildly reduced height and Type III had marked height reduction). Fractures were common across all OI groups. The annualized fracture rates were highest in younger patients (288.31 per 1,000 person years) and patients with Type III, Type IV OI and unknown type. Skeletal deformities were present across all OI types and in every age group, with trunk deformities being most frequently reported. An estimated 10-30% of all patients suffered from functional limitations. Extraskeletal manifestations (skin abnormalities, hearing loss, valvulopathies, scleral discoloration, joint hyperlaxity, and dental abnormalities) were common. Conclusion: Various parameters including height, weight, fractures, and skeletal and extraskeletal deformities vary by OI type and patient age. These findings support the need for phenotype-informed, life-course care planning with the need for adaptations for age-related patterns to optimize patient care.