Osteogenesis imperfecta (OI) is a congenital connective tissue disorder characterized by severe osteoporosis, bone fragility, and other features such as dentinogenesis imperfecta, scoliosis, short stature, blue sclerae, hearing loss, and skin and ligament laxity. It is the most commonly inherited connective tissue disorder, with a prevalence of about 25,000-50,000 cases in the United States. OI is primarily caused by mutations in the COL1A1 and COL1A2 genes, which encode type I collagen. However, about 10-15% of cases are due to recessive mutations in non-collagen genes. OI is classified into several types based on clinical, radiological, and genetic features. Type II is perinatally lethal, while types III, IV, and I are less severe, with type I being the mildest. Recent classifications have expanded to include new types due to mutations in different genes. OI management includes bisphosphonate treatment, which improves bone density and reduces fractures, but does not remodel existing deformities. Surgical interventions are used for severe cases with recurrent fractures and deformities. Molecular genetics has identified several genes responsible for both dominant and recessive OI, including CRTAP, LEPRE1, PPIB, FKBP65, SERPINH1, and SERPINF1. These genes are involved in collagen synthesis and processing, and mutations in them lead to various forms of OI. Mouse models have been developed to study OI, including the oim mouse and Mov13 mouse, which mimic different forms of OI. These models help in understanding the disease mechanisms and developing potential therapies.Osteogenesis imperfecta (OI) is a congenital connective tissue disorder characterized by severe osteoporosis, bone fragility, and other features such as dentinogenesis imperfecta, scoliosis, short stature, blue sclerae, hearing loss, and skin and ligament laxity. It is the most commonly inherited connective tissue disorder, with a prevalence of about 25,000-50,000 cases in the United States. OI is primarily caused by mutations in the COL1A1 and COL1A2 genes, which encode type I collagen. However, about 10-15% of cases are due to recessive mutations in non-collagen genes. OI is classified into several types based on clinical, radiological, and genetic features. Type II is perinatally lethal, while types III, IV, and I are less severe, with type I being the mildest. Recent classifications have expanded to include new types due to mutations in different genes. OI management includes bisphosphonate treatment, which improves bone density and reduces fractures, but does not remodel existing deformities. Surgical interventions are used for severe cases with recurrent fractures and deformities. Molecular genetics has identified several genes responsible for both dominant and recessive OI, including CRTAP, LEPRE1, PPIB, FKBP65, SERPINH1, and SERPINF1. These genes are involved in collagen synthesis and processing, and mutations in them lead to various forms of OI. Mouse models have been developed to study OI, including the oim mouse and Mov13 mouse, which mimic different forms of OI. These models help in understanding the disease mechanisms and developing potential therapies.