Project description:Osteogenesis imperfecta (OI) is a kind of heritable connective tissue disorder, including blue sclerae, hearing loss, skeletal dysplasia causing bone fragility and deformities. It is typically caused by collagen related gene mutations, which could lead to bone formation abnormalities. Scoliosis is one of the most common and severe spinal phenotype which has been reported in approximately 26-74.5% of all OI patients. Recent breakthroughs have suggested that OI can be divided into more than 16 types based on genetic mutations with different degrees of scoliosis. In this review, we summarize the etiology of scoliosis in OI, especially the genetic studies of different types. We aim to provide a systematic review of the genetic etiology and clinical suggestions of scoliosis in OI.
Project description:In this study, our objective is to broaden the understanding of the genetic and clinical characteristics of OI by investigating rare pathogenic variants (PVs) not only within the well-established COL1A1 and COL1A2, which are responsible for more than 85-90% of all cases but also in other genes involved in OI. To achieve this, we performed next-generation sequencing (NGS) analysis on OI patients from the Puglia Region in South Italy, a population with limited genetic data on OI
Project description:Osteogenesis imperfecta is a phenotypically and molecularly heterogeneous group of inherited connective tissue disorders that share similar skeletal abnormalities causing bone fragility and deformity. Previously, the disorder was thought to be an autosomal dominant bone dysplasia caused by defects in type I collagen, but in the past 10 years discoveries of novel (mainly recessive) causative genes have lent support to a predominantly collagen-related pathophysiology and have contributed to an improved understanding of normal bone development. Defects in proteins with very different functions, ranging from structural to enzymatic and from intracellular transport to chaperones, have been described in patients with osteogenesis imperfecta. Knowledge of the specific molecular basis of each form of the disorder will advance clinical diagnosis and potentially stimulate targeted therapeutic approaches. In this Seminar, together with diagnosis, management, and treatment, we describe the defects causing osteogenesis imperfecta and their mechanism and interrelations, and classify them into five groups on the basis of the metabolic pathway compromised, specifically those related to collagen synthesis, structure, and processing; post-translational modification; folding and cross-linking; mineralisation; and osteoblast differentiation.
Project description:Osteogenesis imperfecta, or brittle bone disease, is a congenital disease that primarily causes low bone mass and bone fractures but it can negatively affect other organs. It is usually inherited in an autosomal dominant fashion, although rarer recessive and X-chromosome-linked forms of the disease have been identified. In addition to type I collagen, mutations in a number of other genes, often involved in type I collagen synthesis or in the differentiation and function of osteoblasts, have been identified in the last several years. Seldom, the study of a rare disease has delivered such a wealth of new information that have helped our understanding of multiple processes involved in collagen synthesis and bone formation. In this short review I will describe the clinical features and the molecular genetics of the disease, but then focus on how OI dysregulates all aspects of extracellular matrix biology. I will conclude with a discussion about OI therapeutics.
Project description:Osteogenesis imperfecta (OI) is the term used to describe a group of rare inherited skeletal disorders characterized by a greatly increased risk of fragility fractures (1). Mutations in several genes can cause OI but the condition is most commonly caused by mutations of COLIA1 or COL1A2 resulting in the production of collagen which is abnormal or present in reduced amounts. Fractures in OI are particularly common during childhood but the elevated fracture risk continues throughout life. Bone mineral density (BMD) can be reduced in OI but the magnitude of increase in fracture risk is far greater than can be accounted for by low BMD, highlighting that a key mechanism of bone fragility is reduced bone quality due to defects of bone matrix and mineralization. A multidisciplinary approach is needed to optimize management of OI, with input from physicians, orthopedic surgeons, physiotherapists, occupational therapists, and other allied health professionals. Orthopedic surgery plays a key role both in the fixation of fractures and in the correction of limb deformities. Bisphosphonates have been widely used in the treatment of children and adults with OI. Although there is good evidence that they increase BMD, it is uncertain to what extent they reduce fracture risk. Clinical trials of bone anabolic drugs such as teriparatide and inhibitors of sclerostin have also been studied; although they increase BMD, studies of these agents have not been powered to look at fracture endpoints. Various other treatment modalities including denosumab, and cell therapy have been explored but haven't gained acceptance in routine clinical practice. There have been huge advances in understanding the pathogenesis of OI but these have not been accompanied by advances in treatment. This signals need for well-designed clinical trials with fracture endpoints in OI, both with existing agents and with the newer therapeutic agents that are now starting to emerge.
Project description:Osteogenesis Imperfecta (OI) is a heterogeneous genetic disorder characterized by bone fragility and fracture. Mutations in 20 distinct genes can cause OI, and therefore, the genetic diagnosis of OI is frequently difficult to obtain because of the great number of genes that can be related with this disease. Studies that report the most frequently mutated genes in OI patients can help to improve molecular strategies for diagnosis of the disease. In order to characterize the mutation profile of OI in Brazilian patients, we analyzed 30 unrelated patients through SSCP screening, NGS gene panel, and/or Sanger sequencing for the 11 most frequently mutated genes in the database of mutations, including COL1A1, COL1A2, P3H1, CRTAP, PPIB, SERPINH1, SERPINF1, FKBP10, SP7, WNT1 and IFITM5. Disease-causing variants were identified in COL1A1, COL1A2, FKBP10, P3H1, and IFITM5. A total of 28 distinct mutations were identified, including seven novel changes. Our data show that the analysis of these five genes is able to detect at least 95% of causative mutations in OI disorder from Brazilian population. However, it has to be taken into considerations that distinct populations can have different frequencies of disease-causing variants. Hence, it is important to replicate this study in other groups.
Project description:A new paradigm has emerged for osteogenesis imperfecta as a collagen-related disorder. The more prevalent autosomal dominant forms of osteogenesis imperfecta are caused by primary defects in type I collagen, whereas autosomal recessive forms are caused by deficiency of proteins which interact with type I procollagen for post-translational modification and/or folding. Factors that contribute to the mechanism of dominant osteogenesis imperfecta include intracellular stress, disruption of interactions between collagen and noncollagenous proteins, compromised matrix structure, abnormal cell-cell and cell-matrix interactions and tissue mineralization. Recessive osteogenesis imperfecta is caused by deficiency of any of the three components of the collagen prolyl 3-hydroxylation complex. Absence of 3-hydroxylation is associated with increased modification of the collagen helix, consistent with delayed collagen folding. Other causes of recessive osteogenesis imperfecta include deficiency of the collagen chaperones FKBP10 or Serpin H1. Murine models are crucial to uncovering the common pathways in dominant and recessive osteogenesis imperfecta bone dysplasia. Clinical management of osteogenesis imperfecta is multidisciplinary, encompassing substantial progress in physical rehabilitation and surgical procedures, management of hearing, dental and pulmonary abnormalities, as well as drugs, such as bisphosphonates and recombinant human growth hormone. Novel treatments using cell therapy or new drug regimens hold promise for the future.
Project description:Osteogenesis imperfecta (OI) is an inherited connective tissue disorder with skeletal dysplasia of varying severity, predominantly caused by mutations in the collagen I genes (COL1A1/COL1A2). Extraskeletal findings such as cardiac and pulmonary complications are generally considered to be significant secondary features. Aga2, a murine model for human OI, was systemically analyzed in the German Mouse Clinic by means of in vivo and in vitro examinations of the cardiopulmonary system, to identify novel mechanisms accounting for perinatal lethality. Pulmonary and, especially, cardiac fibroblast of perinatal lethal Aga2/+ animals display a strong down-regulation of Col1a1 transcripts in vivo and in vitro, resulting in a loss of extracellular matrix integrity. In addition, dysregulated gene expression of Nppa, different types of collagen and Agt in heart and lung tissue support a bone-independent vicious cycle of heart dysfunction, including hypertrophy, loss of myocardial matrix integrity, pulmonary hypertension, pneumonia and hypoxia leading to death in Aga2. These murine findings are corroborated by a pediatric OI cohort study, displaying significant progressive decline in pulmonary function and restrictive pulmonary disease independent of scoliosis. Most participants show mild cardiac valvular regurgitation, independent of pulmonary and skeletal findings. Data obtained from human OI patients and the mouse model Aga2 provide novel evidence for primary effects of type I collagen mutations on the heart and lung. The findings will have potential benefits of anticipatory clinical exams and early intervention in OI patients.
Project description:Osteogenesis Imperfecta (OI) is a group of connective tissue disorders with a broad range of phenotypes characterized primarily by bone fragility. The prevalence of OI ranges from about 1:15,000 to 1:20,000 births. Five types of the disease are commonly distinguished, ranging from a mild (type I) to a lethal one (type II). Types III and IV are severe forms allowing survival after the neonatal period, while type V is characterized by a mild to moderate phenotype with calcification of interosseous membranes. In most cases, there is a reduction in the production of normal type I collagen (col I) or the synthesis of abnormal collagen as a result of mutations in col I genes. Moreover, mutations in genes involved in col I synthesis and processing as well as in osteoblast differentiation have been reported. The currently available treatments try to prevent fractures, control symptoms and increase bone mass. Commonly used medications in OI treatment are bisphosphonates, Denosumab, synthetic parathyroid hormone and growth hormone for children therapy. The main disadvantages of these therapies are their relatively weak effectiveness, lack of effects in some patients or cytotoxic side effects. Experimental approaches, particularly those based on stem cell transplantation and genetic engineering, seem to be promising to improve the therapeutic effects of OI.