Osteogenesis imperfecta:epidemiology and pathophysiology

Prevalence, number of fractures, and hospital characteristics among the pediatric population with osteogenesis imperfecta: results from the nationwide registry of Türkiye

OBJECTIVE

Osteogenesis imperfecta is a rare connective tissue disorder with an estimated number of 4-20 cases per 100 000 inhabitants. Although the prevalence differs among regions, there are only a few number of national registry studies published previously. The aim of this study was to determine the prevalence of osteogenesis imperfecta among the pediatric age group in Türkiye, together with the patient and hospital characteristics.

METHODS

Via the e-health database of the Turkish Ministry of Health, we collected and retrospectively evaluated the medical records of the patients who were under 18 years of age with the diagnosis of osteogenesis imperfecta between 2016 and 2022. Total number of fractures, treatment modalities, and the hospital characteristics were also recorded. Two thousand seven hundred forty patients were extracted with a mean age of 9.77 ± 4.81 years.

RESULTS

The prevalence of osteogenesis imperfecta in Türkiye among the pediatric population was calculated as 11.6 per 100 000 individuals. The median annual incidence was 31.5 per 100 000 live births between 2016 and 2022. There were 17.4 hospital admissions per patient per year. The mean age at the time of in-hospital mortality was 4.08 ± 5.03 years. The fracture rate per patient per year was 0.56 and conservative treatment was the most commonly preferred modality for all ages.

CONCLUSION

This is the first registry-based nationwide study of osteogenesis imperfecta patients in Türkiye, providing important characteristics of the disease. Together with the help of the ongoing development of national health database systems, precision in patient identification would yield substantial benefits in terms of management of osteogenesis imperfecta.

AAV-based gene editing of type 1 collagen mutation to treat osteogenesis imperfecta

Osteogenesis imperfecta (OI) is a genetic disorder characterized by bone fragility, low bone mass, fractures, and extraskeletal manifestations. Since OI is commonly caused by single-nucleotide mutation(s) in the COL1A1 or COL1A2 genes encoding type I collagens, we developed a genome-editing strategy to correct a Col1a2 mutation in an OIM mouse model resembling a severe dominant form of human type III OI. Using a recombinant adeno-associated virus (rAAV), we delivered CRISPR-Cas9 to bone-forming osteoblast-lineage cells in the skeleton. Homology-directed repair (HDR)-mediated gene editing efficiency in these cells was improved when CRISPR-Cas9 was coupled with a donor AAV vector containing a promoterless partial mouse Col1a2 complementary DNA sequence. This approach effectively reversed the dysregulation of osteogenic differentiation by a Col1a2 mutation in vitro. Furthermore, systemic administration of dual rAAVs in OIM mice lowered bone matrix turnover rates by reducing osteoblast and osteoclast development while improving the cellular network of mechano-sensing osteocytes embedded in the bone matrix. This strategy significantly improved bone architecture/mass/mineralization, skeletal deformities, grip strength, and spontaneous fractures. Our study is the first demonstration that HDR-mediated gene editing via AAV-mediated delivery effectively corrects a collagen mutation in OI osteoblasts and reverses skeletal phenotypes in OIM mice.

Psychosocial Outcomes of Pain and Pain Management in Adults with Osteogenesis Imperfecta: A Qualitative Study

Osteogenesis imperfecta (OI) is a genetic disorder characterized by bone fragility and fractures, short stature, dental abnormalities, hearing loss, scoliosis, and chronic pain. Despite a growing literature on the functional outcomes of OI, limited research has explicitly examined the psychosocial outcomes of pain within OI. Adults with OI (N = 15) were interviewed to understand pain-related experiences through a thematic analysis of semi-structured interview data. Research team members, genetic research experts, and OI clinicians developed an interview guide focused on topics related to pain and mental health challenges. Participants' transcripts were coded by two independent coders; codes were then merged across coders and quotation outputs were subsequently abstracted (paraphrased then thematically classified) to identify common themes. Themes related to pain management variability regarding pain type, pain risk management and accessibility, pain outcomes (e.g., behavior, cognitive, affective), and pain exacerbating factors (e.g., individual, contextual) were identified. Participants reported chronic and acute pain, and despite the inaccessibility and stigmatization of pain medications (e.g., opioids), pharmacological treatments were the most common pain management approach. Participants reported negative pain outcomes, such as limited daily functioning and activity participation, fear, anger, anxiety, depression, and difficulty concentrating. Lastly, participants suggested that lack of physician and community knowledge on chronic pain in OI indirectly exacerbates both subjective pain intensity and outcomes. Although limited by a small, nondiverse sample, the current study provides valuable exploration of the unique pain experiences of adults with OI that may have implications for proactive management, treatment development, and clinician training.

Acetabular Fracture in a Skeletally Mature Patient With Osteogenesis Imperfecta Treated With Open Reduction Internal Fixation: A Case Report

Patients with osteogenesis imperfecta often present with and are managed for various fractures given the brittle bones associated with this disease. Acetabular fractures are one of the most complicated presentations and management is often strenuous on both the patient and the treating surgeon. There is a lack of evidence on how to approach these patients and not many cases reported in the literature. Open reduction and internal fixation can be successful for these patients given extra care is undergone to protect the patient's increased risk of intra-operative and post-operative complications, and a thorough understanding of the pathophysiology of this disease.

Exploring the relationship between personality and chronic pain in adults with osteogenesis imperfecta: A cross-sectional study

Despite the growing body of research on chronic pain in adults with osteogenesis imperfecta (OI), there is still a lack of comprehensive understanding of the influence of psychological factors on pain experienced by individuals with this condition. This study aims to delve into the correlation between personality traits and various aspects of pain, such as frequency, intensity, appraisal, and coping mechanisms, in a significant sample of adults with OI. Additionally, the investigation seeks to identify whether certain personality profiles may be more susceptible to chronic pain within this specific population. A descriptive cross-sectional study was conducted on a sample of 418 adults diagnosed with OI. Participants completed an online survey that assessed sociodemographic and clinical variables, pain parameters, personality traits, pain appraisal, and coping strategies. Subsequently, descriptive, correlational, cluster and comparative analyses were performed. Up to 83% of the participants reported experiencing pain on a regular basis. Regarding personality dimensions, moderate scores were obtained, with no significant differences compared to the general population. Neuroticism emerged as the trait showing the most robust relationships with the evaluated variables. It positively correlated with pain intensity, frequency, and the perception of pain as threatening (P < .001). Conversely, higher levels of extraversion were associated with a reduction in pain and its threatening perception (P < .001). Finally, the cluster analysis revealed a personality profile that showed greater vulnerability in pain adaptation, characterized by high levels of neuroticism and low levels of extraversion, agreeableness, and conscientiousness. Chronic pain is prevalent in adults with OI. Personality dimensions maintain a significant relationship with this pain, acting as vulnerability or protective factors. Consequently, specific personality profiles are associated with poorer adaptation. Understanding these profiles would allow for a deeper comprehension of the pain experience in adults with OI.

The International Standard Set of Outcome Measures for the Assessment of Hearing in People with Osteogenesis Imperfecta

OBJECTIVE

The aim is to recommend a minimum standard set of clinician-reported outcome measures (CROMs) and patient-reported outcome measures (PROMs) on hearing for people with osteogenesis imperfecta (OI). This project is part of the larger "Key4OI" project initiated by the "Care4BrittleBones foundation" of which the goal is to improve quality of life of people with OI. Key4OI provides a standard set of outcome measures and covers a large set of domains affecting the well-being of people with OI.

METHODS

An international team of experts in OI, comprising specialists in audiological science, medical specialists, and an expert patient representative, used a modified Delphi consensus process to select CROMs and PROMs to evaluate hearing problems in people with OI. In addition, focus groups of people with OI identified key consequences of their hearing loss. These criteria were matched to categories of preselected questionnaires to select a PROM that matched their specific hearing-related concerns best.

RESULTS

Consensus on PROMs for adults and CROMs for adults and children was reached. The focus of the CROMs was on specific audiological outcome measures and standardized follow-up.

CONCLUSIONS

This project resulted in a clear consensus statement for standardization of hearing-related PROMs and CROMs and follow-up management of patients with OI. This standardization of outcome measurements will facilitate comparability of research and easier international cooperation in OI and hearing loss. Furthermore, it can improve standard of care in people with OI and hearing loss by incorporating the recommendations into care pathways.

Quality of life of pediatric and adult individuals with osteogenesis imperfecta: a meta-analysis

BACKGROUND

Osteogenesis imperfecta (OI) is a group of rare inheritable disorders of connective tissue. The cardinal manifestations of OI are low bone mass and reduced bone mineral strength, leading to increased bone fragility and deformity that may lead to significant impairment in daily life. The phenotypic manifestations show a broad range of severity, ranging from mild or moderate to severe and lethal. The here presented meta-analysis aimed to analyze existing findings on quality of life (QoL) in children and adults with OI.

METHODS

Nine databases were searched with predefined key words. The selection process was executed by two independent reviewers and was based on predetermined exclusion and inclusion criteria. The quality of each study was assessed using a risk of bias tool. Effect sizes were calculated as standardized mean differences. Between-study heterogeneity was calculated with the I² statistic.

RESULTS

Among the studies included two featured children and adolescents (N = 189), and four adults (N = 760). Children with OI had significantly lower QoL on the Pediatric quality of life inventory (PedsQL) with regards to the total score, emotional, school, and social functioning compared to controls and norms. The data was not sufficient to calculate differences regarding OI-subtypes. In the adult sample assessed with Short Form Health Survey Questionnaire, 12 (SF-12) and 36 items (SF-36), all OI types showed significantly lower QoL levels across all physical component subscales compared to norms. The same pattern was found for the mental component subscales namely vitality, social functioning, and emotional role functioning. The mental health subscale was significantly lower for OI type I, but not for type III and IV. All of the included studies exhibited a low risk of bias.

CONCLUSIONS

QoL was significantly lower in children and adults with OI compared to norms and controls. Studies in adults comparing OI subtypes showed that the clinical severity of the phenotype is not related to worse mental health QoL. Future research is needed to examine QoL in children and adolescents in more sophisticated ways and to better understand the association between clinical severity of an OI-phenotype/severity and mental health in adults.

Morphological and Ultrastructural Collagen Defects: Impact and Implications in Dentinogenesis Imperfecta

Collagen is the building block for the extracellular matrix in bone, teeth and other fibrous tissues. Osteogenesis imperfecta (OI), or brittle bone disease, is a heritable disorder that results from defective collagen synthesis or metabolism, resulting in bone fragility. The dental manifestation of OI is dentinogenesis imperfecta (DI), a genetic disorder that affects dentin structure and clinical appearance, with a characteristic feature of greyish-brown discolouration. The aim of this study was to conduct a systematic review to identify and/or define any ultrastructural changes in dentinal collagen in DI. Established databases were searched: Cochrane Library, OVID Embase, OVID Medline and PubMed/Medline. Search strategies included: Collagen Ultrastructure, DI and OI. Inclusion criteria were studies written in English, published after 1990, that examined human dental collagen of teeth affected by DI. A Cochrane data extraction form was modified and used for data collection. The final dataset included seventeen studies published from 1993 to 2021. The most prevalent findings on collagen in DI teeth were increased coarse collagen fibres and decreased fibre quantity. Additional findings included changes to fibre orientation (i.e., random to parallel) and differences to the fibre organisation (i.e., regular to irregular). Ultrastructural defects and anomalies included uncoiled collagen fibres and increased D-banding periodicity. Studies in collagen structure in DI reported changes to the surface topography, quantity, organisation and orientation of the fibres. Moreover, ultrastructural defects such as the packing/coiling and D-banding of the fibrils, as well as differences in the presence of other collagens are also noted. Taken together, this study provides an understanding of the changes in collagen and its impact on clinical translation, paving the way for innovative treatments in dental treatment.

Systematic review of health related-quality of life in adults with osteogenesis imperfecta

BACKGROUND

Osteogenesis imperfecta (OI) is a rare, connective tissue disorder characterised by bone fragility, resulting in recurrent fractures and skeletal deformities. Extra-skeletal manifestations include dentinogenesis imperfecta, hearing abnormalities and lung disease. These co-morbidities combined with recurrent fractures can exert a significant impact on health-related quality of life (HR-QOL). It is important to assess HR-QOL throughout adulthood because the prevalence of some OI-specific complications increases with age.

METHODS

PubMed, EMBASE and CENTRAL databases were searched on 2nd February 2022 to identify studies reporting quantitative assessments of HR-QOL in adults with OI. The primary endpoint was to determine the impact of an OI diagnosis on adult's HR-QOL. Secondary endpoints were to (i) examine how frequently various HR-QOL assessment tools were used (ii) identify differences in HR-QOL between OI types and (iii) investigate the determinants of HR-QOL in adults with OI. Search results were exported to Endnote where two reviewers independently conducted title/abstract and full-text reviews. Data from accepted studies were extracted into Microsoft Excel. A narrative synthesis was then undertaken.

RESULTS

The review identified 17 studies with a total of 1,648 adults. The Short Form-36 (SF-36) was the most frequently reported HR-QOL assessment tool and was used in nine studies. Physical HR-QOL was reduced in adults with OI. Physical component scores (PCS) or individual physical domains of the SF-36 were lower in eight of nine studies. Mental component scores (MCS) were preserved in all six studies, however individual mental health domains of the SF-36 were reduced in some studies. The prevalence of anxiety/depression was relatively low in adults with OI. Those with type III OI had lower physical and respiratory HR-QOL but preserved mental HR-QOL compared with type I. The prevalence of fatigue and pain was higher in adults with OI compared with reference populations. Age and cardio-pulmonary co-morbidities were associated with lower HR-QOL.

CONCLUSION

OI in adulthood has a wide-ranging negative impact on HR-QOL. Physical and respiratory HR-QOL were lower, while the prevalence of pain and fatigue were higher than in reference populations. Mental HR-QOL was relatively preserved, although some deficits were identified. Age and cardio-pulmonary co-morbidities were associated with lower HR-QOL.

Scoliosis in osteogenesis imperfecta: results of posterior spinal fusion in 39 patients

PURPOSE

To evaluate the outcomes of scoliosis corrective surgery in Osteogenesis Imperfecta (OI) patients with primarily pedicles screw fixation in terms of correcting and maintaining the correction of the spinal deformity, and to assess for several peri-operative parameters and complications associated with this surgical treatment.

METHODS

Retrospective case series of 39 consecutive patients with OI treated surgically for scoliosis. The surgeries were performed between 2002 and 2020 by three different surgeons. All patients' medical peri-operative and post-operative charts were evaluated. Radiological assessment was performed by evaluation of the pre-operative, immediate post-operative and last follow-up plain radiographs.

RESULTS

There were 20 females and 19 males included in this review with a mean age of 14 years (range, 6-20 years) at the time of surgery. The median follow-up time was 7.9 years. The mean pre-operative cobb angle (CA) of the major curve was 76.5 degrees (SD ± 18.9), decreasing to 42.6 (SD ± 17.4) in the long-term post-operative follow-up (P < 0.001). A total of 21 adverse events in 16 patients were noted. Only 4 patients required subsequent invasive surgical treatment or prolonged hospital stay. All other patients were treated conservatively with no lasting complication.

CONCLUSION

Scoliosis surgical correction in OI patients seems to yield acceptable results, with maintained coronal plane surgical correction in the long-term follow-up. Even though a high peri-operative complications rate is observed in this series, there were no long-term sequelae or lasting complications.

LEVEL OF EVIDENCE

Level IV, Case series.

Mesenchymal stem cells in the treatment of osteogenesis imperfecta

Osteogenesis imperfecta (OI) is a disease caused by mutations in different genes resulting in mild, severe, or lethal forms. With no cure, researchers have investigated the use of cell therapy to correct the underlying molecular defects of OI. Mesenchymal stem cells (MSCs) are of particular interest because of their differentiation capacity, immunomodulatory effects, and their ability to migrate to sites of damage. MSCs can be isolated from different sources, expanded in culture, and have been shown to be safe in numerous clinical applications. This review summarizes the preclinical and clinical studies of MSCs in the treatment of OI. Altogether, the culmination of these studies show that MSCs from different sources: 1) are safe to use in the clinic, 2) migrate to fracture sites and growth sites in bone, 3) engraft in low levels, 4) improve clinical outcome but have a transient effect, 5) have a therapeutic effect most likely due to paracrine mechanisms, and 6) have a reduced therapeutic potential when isolated from patients with OI.

Chronic pain in adults with osteogenesis imperfecta and its relationship to appraisal, coping, and quality of life: A cross-sectional study

Chronic pain is a common experience in osteogenesis imperfecta (OI). However, there are few studies on this topic, and none of them emerge from psychology as a discipline. The purpose of this work is to describe the frequency of chronic pain and its characteristics in a large sample of adults with OI, as well as its relationship with clinical, sociodemographic, psychological, and quality of life variables. A cross-sectional study was carried out in a sample of 418 adults with OI who answered a battery of online questionnaires. Sociodemographic and clinical variables, pain parameters, participants' appraisal of pain, coping strategies, interference in daily activities, and health-related quality of life were evaluated. A descriptive and correlational analysis was performed. Up to 83% of the sample reported experiencing pain frequently. Both the frequency and intensity of pain were related to the accumulation of fractures over the years (P < .05), but were independent of other variables like the severity of the pathology or the use of bisphosphonates. Higher threat appraisal of pain was associated with an increase in perceived pain intensity and its interference with daily activities, as well as a decrease in physical and mental health (P < .001). Chronic pain frequent condition in adults with OI, regardless of the severity of the pathology. It interferes with their usual activities and has an impact on their quality of life. The way in which participants appraise their pain also have an influence on its intensity and its consequences. Interventions aimed at training strategies for managing appraisals about pain could potentially improve adaptation to chronic pain.

Accelerated aging in cyclophilin B deficient mice downstream of p21‐Cip1 /Waf1

Loss of bone mass and strength is a common problem of advanced age in humans. Defective bone is also a primary finding in osteogenesis imperfecta (OI), a genetic condition most commonly caused by autosomal dominant mutations in the type I collagen genes. Although altered collagen has been proposed to correlate with cellular processes that underlie aging, the causal relationships between them in vivo have not yet been completely explored. Whether aging plays a promoting role in OI development or whether OI contributes to aging, also remains unknown. The PpiB gene encodes cyclophilin B (CypB), a prolyl isomerase residing in the endoplasmic reticulum required for normal assembly of collagen. Germline deletion or mutations of CypB in mice or humans cause autosomal recessive OI (type IX). Here, we show that mice lacking CypB develop early onset of aging‐associated phenotypes, including kyphosis, fat reduction and weight loss, as well as abnormal teeth, skin, and muscle. Elevated senescence‐associated beta‐galactosidase (SA‐β‐Gal) activity was observed in fat tissues and in bone marrow–derived multipotent stromal cells. Protein levels of the cyclin‐dependent kinase (cdk)‐inhibitor p21‐Cip1/Waf1, a well known senescence marker, were significantly elevated in CypB‐deficient primary cells and mouse tissues. Importantly, loss of p21 in CypB knockout mice attenuated SA‐β‐Gal activity and delayed the development of kyphosis. In addition, less adipose tissue depot and higher SA‐β‐Gal activity were observed in a second OI model, Cola2^oim mutant mice. A potential upregulation of p21 was also revealed in a limited number of these mice. These findings suggest that some of the features in OI patients may be mediated in part through activation of the p21‐dependent pathway, one of which is closely associated with senescence and aging. This study provides new mechanistic insight into relationships between OI and aging and raises the possibility of using senolytics drugs to treat OI in the future. © 2022 The Authors. JBMR Plus published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research.

Delayed Diagnosis of Osteogenesis Imperfecta: A Differential Diagnosis Guided by Competing Ocular Findings and a Lack of Family History

Osteogenesis imperfecta (OI) is an inherited connective tissue disorder with variable clinical manifestations involving many structures and organ systems, leading to characteristic presentations such as low bone mineral density (BMD), vertebral compression fractures, hearing loss, and blue sclerae. Even within the same family, individuals with the same inherited genotype may have differential presentations due to variable expressivity. Early diagnosis of OI in the pediatric population may allow for earlier treatment and interprofessional interventions. This case describes a minority female infant who initially presented with bilateral complexion-associated melanosis (CAM) inclusions in her eyes. The appearance of her inclusions was reminiscent of the blue sclera seen in OI; however, there was no clinical suspicion for OI on birth, developmental, and family histories. Her growth and development were unremarkable at all well-child checks until her three-year well-child check. It was then discovered that she suffered multiple long bone fractures due to low trauma, vertebral compression fractures, and kyphoscoliosis. Due to the occurrence of these fragility fractures, she was given a clinical diagnosis of osteoporosis with pending genetic testing for osteogenesis imperfecta. It was later discovered that there was, in fact, an extensive history of recurrent childhood fractures in the patient’s brother, mother, and numerous maternal relatives. Our case demonstrates the greater need for certified medical interpretation services to obtain clear past medical and family history, especially in the face of language barriers and low health literacy, in conjunction with clinical findings, i.e., CAM, to guide the differential diagnosis and subsequent management appropriately.

Cementless posterior spinal fusion for the treatment of OI patients with severe spine deformity-a case series

PURPOSE

The purpose of this study is to present the outcomes all patients with osteogenesis imperfecta (OI) who underwent cementless posterior spinal fusion for the treatment of severe spine deformity in our institution.

METHODS

All patients with OI who underwent surgical correction of their spine deformity in our institution between 2003 and 2020 were enrolled. The collected data included demographics, operative and follow-up findings, medical history, bisphosphonate therapy, HGT protocol, pre- and post-HGT and postoperative scoliosis and kyphosis curve measurements, hospitalization length, complications, and revision surgeries. General treatment strategies included cessation of bisphosphonate therapy around the surgery, 30-day HGT protocol, titanium rods, cementless screw technique, and a high implant density policy.

RESULTS

Eleven consecutive patients with OI who underwent surgery for spine deformity in our institution were identified. The mean age at surgery was 15.6 ± 2.3. Mean follow-up period was 6.6 ± 5.8 years. The mean pre- and postoperative scoliosis curves were 85.4 ± 19.3° and 43.1 ± 12.5°, respectively, representing a 49.5% correction rate. Five patients underwent HGT and achieved a mean correction of 27.6 ± 7.1° (31.6%) preoperatively. Implant density ratio was 1.5 (screw or hook/level). Mean postoperative hospitalization length was 5.9 ± 1.6 days. One patient had deep wound infection which resolved following treatment according to our protocol for surgical site infection, and one patient had skull penetration by one of the halo pins.

CONCLUSION

Surgical treatment of severe spine deformity in OI patients with cementless posterior spinal fusion is safe and effective after applying a specific preoperative strategy.

Osteogenesis Imperfecta Type 3 in a 10-Year-Old Child With Acute Respiratory Distress Syndrome

Osteogenesis imperfecta (OI) represents a group of rare connective tissue disorders characterized by excessive bone fragility. Type 3 is a rare form with new mutations; osteopenia and bone fragility are significant with numerous fractures, continuous and severe deformity of the spine, and long bones. Our case study concerns a 10-year-old male child admitted to the pediatric department of the State University of Haiti Hospital. OI type 3 was diagnosed based on both clinical and radiological assessments. Multidisciplinary care was initiated. Although the evolution was still unsatisfactory, characterized by intermittent episodes of dyspnea and left lung hypoplasia, he was stabilized after 28 days of hospitalization and referred to the orthopedics department for follow-up care.

Fabric-elasticity relationships of tibial trabecular bone are similar in osteogenesis imperfecta and healthy individuals

Osteogenesis Imperfecta (OI) is an inherited form of bone fragility characterised by impaired synthesis of type I collagen, altered trabecular bone architecture and reduced bone mass. High resolution peripheral computed tomography (HR-pQCT) is a powerful method to investigate bone morphology at peripheral sites including the weight-bearing distal tibia. The resulting 3D reconstructions can be used as a basis of micro-finite element (FE) or homogenized finite element (hFE) models for bone strength estimation. The hFE scheme uses homogenized local bone volume fraction (BV/TV) and anisotropy information (fabric) to compute healthy bone strength within a reasonable computation time using fabric-elasticity relationships. However, it is unclear if these relationships quantified previously for healthy controls are valid for trabecular bone from OI patients. Thus, the aim of this study is to investigate fabric-elasticity relationships in OI trabecular bone compared to healthy controls. In the present study, the morphology of distal tibiae from 50 adults with OI were compared to 120 healthy controls using second generation HR-pQCT. Six cubic regions of interest (ROIs) were selected per individual in a common anatomical region. A first matching between OI and healthy control group was performed by selecting similar individuals to obtain identical mean and median age and sex distribution. It allowed us to perform a first morphometric analysis and compare the outcome with literature. Then, stiffness tensors of the ROIs were computed using μFE and multiple linear regressions were performed with the Zysset-Curnier orthotropic fabric-elasticity model. An initial fit was performed on both the OI group and the healthy control group using all extracted ROIs. Then, data was filtered according to a fixed threshold for a defined coefficient of variation (CV) assessing ROI heterogeneity and additional linear regressions were performed on these filtered data sets. These full and filtered data were in turn compared with previous results from μCT reconstructions obtained in other anatomical locations. Finally, the ROIs of both groups were matched according to their BV/TV and degree of anisotropy (DA). Linear regressions were performed using these matched data to detect statistical differences between the two groups. Compared to healthy controls, we found the OI samples to have significantly lower BV/TV and trabecular number (Tb.N.), significantly higher CV, trabecular separation (Tb.Sp.) and trabecular separation standard deviation (Tb.Sp.SD), but no differences in trabecular thickness (Tb.Th.). These results are in agreement with previous studies. The stiffnesses of highly heterogeneous ROIs were randomly lower with respect to the fabric-elasticity relationships, which reflects the limit of validity of the computational homogenisation methodology. This limitation does not challenge the fabric-elasticity relationship, which extrapolation to heterogeneous ROIs is probably reasonable but can simply not be evaluated with the employed homogenisation methodology. Moreover, due to their low BV/TV, the potential (unknown) errors on these heterogeneous ROIs would have negligible influence on whole bone stiffness in comparison to homogeneous ROIs which are orders of magnitude stiffer. The filtering of highly heterogeneous ROIs removed these low stiffness ROIs and led to similar correlation coefficients for both OI and healthy groups. Finally, the BV/TV and DA matched data revealed no significant differences in fabric-elasticity parameters between OI and healthy individuals. Moreover, the filtering step did not exclude a particular OI type. Compared to previous studies, the stiffness constants from the 61 μm resolution HR-pQCT ROIs were lower than for the 36 μm resolution μCT ROIs. In conclusion, OI trabecular bone of the distal tibia was shown to be significantly more heterogeneous and have a lower BV/TV than healthy controls. Despite the reduced linear regression parameters found for HR-pQCT images, the fabric-elasticity relationships between OI and healthy individuals are similar when the trabecular bone ROIs are sufficiently homogeneous to perform the computational stiffness analysis. Accordingly, the elastic properties used for FEA of healthy bones are also valid for OI bones.

Osteogenesis Imperfecta: characterization of fractures during pregnancy and post-partum

Background

Pregnancy and breastfeeding are associated with bone density loss. Fracture occurrence during pregnancy and post-partum, and its determinants, remain poorly known in Osteogenesis Imperfecta (OI). The aim of this study was to characterize fractures that occurred during pregnancy and post-partum in OI patients.

Results

We conducted a retrospective multicentric study including a total of 50 previously pregnant OI women from 10 Bone Centers in France. Among these patients, 12 (24%) patients experienced fractures during pregnancy or in the 6 months following delivery, and 38 (76%) did not experience any fracture. The most frequent localizations were: proximal femur (25%), spine (25%), distal femur (12.5%), and pelvis (12.5%). Fractures during pregnancy occurred during the third trimester and post-partum fractures occurred with a mean delay of 2 months following delivery. No fractures occurred during childbirth.

We next compared the 12 patients with pregnancy or post-partum fractures with the 38 patients without fractures. Mean age at pregnancy was 32.7 ± 3.1 years-old in the fractured group, vs 29.3 ± 5.0 years-old in the non-fractured group (p = 0.002). Breastfeeding was reported in 85.7% of patients in the fractured group, vs 47.1% in the non-fractured group (p = 0.03). All patients with post-partum fractures were breastfeeding. Bone mineral density was significantly lower in patients with pregnancy-related fractures compared with other patients: spine Z-score − 2.9 ± 1.6DS vs − 1.5 ± 1.7DS (p = 0.03), and total hip Z-score − 2.0 ± 0.7DS vs − 0.5 ± 1.4DS (p = 0.04). At least one osteoporosis-inducing risk factor or disease other than OI was identified in 81.8% vs 58.6% of fractured vs non-fractured patients (not significant). Fracture during pregnancy or post-partum was not associated with the severity of OI. Bisphosphonates before pregnancy were reported in 16.7% and 21.1% of patients with pregnancy-related fractures and non-fractured patients, respectively (not significant).

Conclusions

OI management during pregnancy and post-partum should aim for optimal control of modifiable osteoporosis risk factors, particularly in patients with low BMD. Breastfeeding should be avoided.

Identification of a Rare Variant of c.1777G>A (p.G593S) in the COL1A1 Gene as the Etiology of Recurrent Osteogenesis Imperfecta by Whole-Exome Sequencing

BACKGROUND

Osteogenesis imperfecta (OI) is a rare heterogeneous disorder typically featured by fragile bones and susceptibility to fracture. The aim of the present study was to explore the genetic etiology of familial recurrent OI and the genotype-phenotype correlation.

METHODS

Karyotyping, chromosomal microarray analysis, and whole-exome sequencing (WES) were performed to determine the genetic etiology of OI in the enrolled family. Western blotting analysis was carried out using the fetal skin tissue for type I collagen production analysis.

RESULTS

At the first pregnancy, a c.1777G>A mutation in the COL1A1 gene was detected in the fetus who exhibited skeletal dysplasia. In this second pregnancy, severe fetal skeletal dysplasia was also presented without significant chromosomal abnormality detected by karyotype and chromosomal microarray analysis in the fetus. Further WES results demonstrated a de novo missense mutation of c.1777G>A (p.G593S) in the fetus, which was classified as a pathogenic variant according to the ACMG guidelines. The recurrent mutation in the two fetuses hinted at the possible existence of gonadal mosaicism in the parents, while no mutation in the COL1A1 gene was identified in the DNA from the father's sperm. In addition, Western blot results demonstrated no reduced type I procollagen production in the affected fetus compared with the age-matched controls.

CONCLUSIONS

To the best of our knowledge, this is the first study that identified a rare variant of c.1777G>A in the COL1A1 gene that led to recurrent OI in the Chinese population. Additionally, we believe that this rare variant of c.1777G>A in the COL1A1 gene will lead to OI type II. The results of the present study further verify the application value of WES in identifying fetuses with ultrasound anomalies.

The osteocyte as a signaling cell

Osteocytes, former osteoblasts encapsulated by mineralized bone matrix, are far from being passive and metabolically inactive bone cells. Instead, osteocytes are multifunctional and dynamic cells capable of integrating hormonal and mechanical signals and transmitting them to effector cells in bone and in distant tissues. Osteocytes are a major source of molecules that regulate bone homeostasis by integrating both mechanical cues and hormonal signals that coordinate the differentiation and function of osteoclasts and osteoblasts. Osteocyte function is altered in both rare and common bone diseases, suggesting that osteocyte dysfunction is directly involved in the pathophysiology of several disorders affecting the skeleton. Advances in osteocyte biology initiated the development of novel therapeutics interfering with osteocyte-secreted molecules. Moreover, osteocytes are targets and key distributors of biological signals mediating the beneficial effects of several bone therapeutics used in the clinic. Here we review the most recent discoveries in osteocyte biology demonstrating that osteocytes regulate bone homeostasis and bone marrow fat via paracrine signaling, influence body composition and energy metabolism via endocrine signaling, and contribute to the damaging effects of diabetes mellitus and hematologic and metastatic cancers in the skeleton.

Left to themselves: Time to target chronic pain in childhood rare diseases

BACKGROUND

Chronic pain is prevalent among patients with rare diseases (RDs). However, little is understood about how biopsychosocial mechanisms may be integrated in the unique set of clinical features and therapeutic challenges inherent in their pain conditions.

METHODS

This review presents examples of major categories of RDs with particular pain conditions. In addition, we provide translational evidence on clinical and scientific rationale for psychosocially- and neurodevelopmentally-informed treatment of pain in RD patients.

RESULTS

Neurobiological and functional overlap between various RD syndromes and pain states suggests amalgamation and mutual modulation of the respective conditions. Emotional sequelae could be construed as an emotional homologue of physical pain mediated via overlapping brain circuitry. Given their clearly defined genetic and molecular etiologies, RDs may serve as heuristic models for unraveling pathophysiological processes inherent in chronic pain.

CONCLUSIONS

Systematic evaluation of chronic pain in patients with RD contributes to sophisticated insight into both pain and their psychosocial correlates, which could transform treatment.

Demographics, in-hospital analysis, and prevalence of 33 rare diseases with effective treatment in Shanghai

BACKGROUND

Rare diseases are ailments which impose a heavy burden on individual patients and global society as a whole. The rare disease management landscape is not a smooth one-a rare disease is quite often hard to diagnose, treat, and investigate. In China, the country's rapid economic rise and development has brought an increased focus on rare diseases. At present, there is a growing focus placed on the importance and public health priority of rare diseases and on improving awareness, definitions, and treatments.

METHODS

In this work we utilized clinical data from the Shanghai HIE System to characterize the status of 33 rare diseases with effective treatment in Shanghai for the time period of 2013-2016.

RESULTS AND CONCLUSION

First, we describe the total number of patients, year-to-year change in new patients with diagnosis in one of the target diseases and the distribution of gender and age for the top six (by patient number) diseases of the set of 33 rare diseases. Second, we describe the hospitalization burden in terms of in-hospital ratio, length of stay, and medical expenses during hospitalization. Finally, rare disease period prevalence is calculated for the rare diseases set.

Tissue Engineering Through 3D Bioprinting to Recreate and Study Bone Disease

The applications of 3D bioprinting are becoming more commonplace. Since the advent of tissue engineering, bone has received much attention for the ability to engineer normal bone for tissue engraftment or replacement. While there are still debates on what materials comprise the most durable and natural replacement of normal tissue, little attention is given to recreating diseased states within the bone. With a better understanding of the cellular pathophysiology associated with the more common bone diseases, these diseases can be scaled down to a more throughput way to test therapies that can reverse the cellular pathophysiology. In this review, we will discuss the potential of 3D bioprinting of bone tissue in the following disease states: osteoporosis, Paget's disease, heterotopic ossification, osteosarcoma, osteogenesis imperfecta, and rickets disease. The development of these 3D bioprinted models will allow for the advancement of novel therapy testing resulting in possible relief to these chronic diseases.

Physical function in UK adults with osteogenesis imperfecta: a cross-sectional analysis of the RUDY study

We describe the physical function in adults with osteogenesis imperfecta (OI) and explored clinical and non-clinical factors related to its impairment. Our data showed that physical dysfunction is a common feature of adults with OI, varying by OI severity, and mediated by the presence and quality of pain and fatigue symptoms.

INTRODUCTION

There is a paucity of data describing physical function in adults with osteogenesis imperfecta (OI). We investigated the effects of OI and its severity on physical function and explored the relationship between physical function and number of fractures and symptomatology.

METHODS

Adults with OI of different types were recruited from the RUDY study, an ongoing UK-based prospective cohort study. Participants completed demographic and clinical questions and questionnaires. These assessed physical function (SF-36), mobility (EQ-5D-5L and NEADL), fatigue (FACIT-F), and pain (SF-MQ-2). Scores were compared using parametric or non-parametric statistical analyses, whereas correlations between outcomes were examined using univariate and multivariate regression analysis.

RESULTS

Seventy-eight adults with OI aged 43.5 ± 14.5 years were enrolled (type I, 32; type III, 11; type IV, 10; unknown type, 26). Physical function (PCS, SF-36) was significantly lower in all participants than normative values (p < 0.001) and in type III than type I (p = 0.008). Mobility was significantly different across the types (EQ-5D-EL, p = 0.007; NEADL, p < 0.001), with type III having more severe problems, followed by types IV, unknown, and I. Physical function was associated with OI type (r = 0.26; p = 0.021), presence and quality of pain (r = - 0.57; p < 0.0001), and fatigue (r = - 0.51; p < 0.0001). Multivariate analysis revealed that physical function correlated independently with age, OI type, fatigue, and non-neuropathic pain.

CONCLUSIONS

Individuals with OI display a marked deterioration in physical function during adulthood. This impairment varies in severity according to the OI phenotype and is associated with the presence of non-neuropathic pain and fatigue.

Comprehensive evaluation of bone health using DXA and pQCT in an Indian boy with osteogenesis imperfecta

We present a 9-year-old male child having history of fractures on trivial trauma with a family history of the same. He was treated for osteogenesis imperfecta (OI; zolendronate, calcium and vitamin D) and showed clinical improvement. On evaluating his bone health using dual energy X-ray absorptiometry and peripheral quantitative CT, we found that the child had bone density within the reference range but a smaller bone mass for his height, low muscle mass and thin bones with a lower strength strain index in comparison with healthy children. Our case suggests that treatment with bisphosphonates results in increase in bone density; however, bones remain thin and the lean body mass in these children may also be low. Controlled physical activity to improve muscle health and newer approaches to improve bone geometry would result in better bone health in children with OI.

Gene Expression Profile and Acute Gene Expression Response to Sclerostin Inhibition in Osteogenesis Imperfecta Bone

Sclerostin antibody (SclAb) therapy has been suggested as a novel therapeutic approach toward addressing the fragility phenotypic of osteogenesis imperfecta (OI). Observations of cellular and transcriptional responses to SclAb in OI have been limited to mouse models of the disorder, leaving a paucity of data on the human OI osteoblastic cellular response to the treatment. Here, we explore factors associated with response to SclAb therapy in vitro and in a novel xenograft model using OI bone tissue derived from pediatric patients. Bone isolates (approximately 2 mm3) from OI patients (OI type III, type III/IV, and type IV, n = 7; non-OI control, n = 5) were collected to media, randomly assigned to an untreated (UN), low-dose SclAb (TRL, 2.5 μg/mL), or high-dose SclAb (TRH, 25 μg/mL) group, and maintained in vitro at 37°C. Treatment occurred on days 2 and 4 and was removed on day 5 for TaqMan qPCR analysis of genes related to the Wnt pathway. A subset of bone was implanted s.c. into an athymic mouse, representing our xenograft model, and treated (25 mg/kg s.c. 2×/week for 2/4 weeks). Implanted OI bone was evaluated using μCT and histomorphometry. Expression of Wnt/Wnt-related targets varied among untreated OI bone isolates. When treated with SclAb, OI bone showed an upregulation in osteoblast and osteoblast progenitor markers, which was heterogeneous across tissue. Interestingly, the greatest magnitude of response generally corresponded to samples with low untreated expression of progenitor markers. Conversely, samples with high untreated expression of these markers showed a lower response to treatment. in vivo implanted OI bone showed a bone-forming response to SclAb via μCT, which was corroborated by histomorphometry. SclAb induced downstream Wnt targets WISP1 and TWIST1, and elicited a compensatory response in Wnt inhibitors SOST and DKK1 in OI bone with the greatest magnitude from OI cortical bone. Understanding patients' genetic, cellular, and morphological bone phenotypes may play an important role in predicting treatment response. This information may aid in clinical decision-making for pharmacological interventions designed to address fragility in OI. © 2020 The Authors. JBMR Plus published by Wiley Periodicals, Inc. on behalf of American Society for Bone and Mineral Research.

Craniofacial allometry in the OIM-/- mouse model of osteogenesis imperfecta

Osteogenesis imperfecta (OI) is a skeletal disorder characterized by the impaired synthesis of type I collagen (Col1). This study tests the hypothesis that the craniofacial phenotype of severe OI is linked to an overall reduction in body size. 3D landmark data were collected from µCT scans of adult OIM^-/- and wild-type (WT) mice and used to calculate centroid sizes (CS) and interlandmark distances (ILDs). To remove the effect of body size, ILDs were scaled against craniomandibular lengths and CS. Mann-Whitney U tests were used to compare CS and absolute/scaled ILDs between genotypes. OIM^-/- mice are smaller than their WT littermates in body mass, craniomandibular CS, and absolute ILDs including skull, basicranial, palatal, mandibular, and toothrow lengths. When linear distances are scaled to CS, OIM^-/- mice have a relatively short midface, short nasal bones, tall mandibular corpora, and long mandibular toothrows. Results underscore the importance of size and scaling in morphometric analyses. The deleterious effect of Col1 mutations on global skeletal dimensions combined with localized morphometric changes may underlie the facial phenotype seen in human patients with severe OI. Attempts to identify these localized changes should first account for the restricted growth and small body sizes present in individuals with OI.

Growing up different in Neolithic China: A contextualised case study and differential diagnosis of a young adult with skeletal dysplasia

This paper presents a case study of a young adult from the late Neolithic Yangshao cultural period site (∼3300-2900 years BC) of Guanjia () located in Henan Province on the Central Plains of China, who has evidence for skeletal dysplasia characterised by proportional stunting of the long bones and a small axial skeleton, generalised osteopenia, and non-fusion of epiphyses. We provide a detailed differential diagnosis of skeletal dysplasia with paediatric onset and conclude that this is likely a form of hypopituitarism or hypothyroidism, an extremely rare finding within the archaeological context. This paper highlights the issues of distinguishing the forms of proportional dwarfism in palaeopathology because of the considerable variation in manifestation of these conditions. Finally, we assess whether there were any health and social implications for this person and community through the consideration of a bioarchaeology of care approach across the lifecourse, burial context, and information on social perceptions of 'difference' in the community. ：： （3300～2900）。，，，，。，，。。，。，、、""，。.

Clinical manifestations of osteogenesis imperfecta in adulthood: An integrative review of quantitative studies and case reports

Osteogenesis imperfecta (OI) is a rare genetic disorder of the bones caused by a mutation in Type I collagen genes. As adults with OI are aging, medical concerns secondary to OI may arise. This integrative review sought to review, appraise, and synthesize the clinical manifestations faced by adults with OI. Four electronic bibliographic databases were searched. Published quantitative, qualitative, and mixed-methods studies, as well as case reports from 2000 to March 2019, addressing a clinical manifestation in adulthood, were reviewed. Eligible studies and case reports were subsequently appraised using the Mixed Methods Appraisal Tool and Case Report Checklist, respectively. Twenty quantitative studies and 88 case reports were included for review regardless of the varying methodological quality score. These studies collectively included 2,510 adults with different OI types. Several clinical manifestations were studied, and included: hearing loss, cardiac diseases, pregnancy complications, cerebrovascular manifestations, musculoskeletal manifestations, respiratory manifestations, vision impairment, and other clinical manifestations. Increased awareness may optimize prevention, treatment, and follow-up. Opportunities to enhance the methodological quality of research including better design and methodology, multisite collaborations, and larger and diverse sampling will optimize the generalizability and transferability of findings.

The Osteocyte as the New Discovery of Therapeutic Options in Rare Bone Diseases

Osteocytes are the most abundant (~95%) cells in bone with the longest half-life (~25 years) in humans. In the past osteocytes have been regarded as vestigial cells in bone, since they are buried inside the tough bone matrix. However, during the last 30 years it has become clear that osteocytes are as important as bone forming osteoblasts and bone resorbing osteoclasts in maintaining bone homeostasis. The osteocyte cell body and dendritic processes reside in bone in a complex lacuno-canalicular system, which allows the direct networking of osteocytes to their neighboring osteocytes, osteoblasts, osteoclasts, bone marrow, blood vessels, and nerves. Mechanosensing of osteocytes translates the applied mechanical force on bone to cellular signaling and regulation of bone adaptation. The osteocyte lacuno-canalicular system is highly efficient in transferring external mechanical force on bone to the osteocyte cell body and dendritic processes via displacement of fluid in the lacuno-canalicular space. Osteocyte mechanotransduction regulates the formation and function of the osteoblasts and osteoclasts to maintain bone homeostasis. Osteocytes produce a variety of proteins and signaling molecules such as sclerostin, cathepsin K, Wnts, DKK1, DMP1, IGF1, and RANKL/OPG to regulate osteoblast and osteoclast activity. Various genetic abnormality-associated rare bone diseases are related to disrupted osteocyte functions, including sclerosteosis, van Buchem disease, hypophosphatemic rickets, and WNT1 and plastin3 mutation-related disorders. Meticulous studies during the last 15 years on disrupted osteocyte function in rare bone diseases guided for the development of various novel therapeutic agents to treat bone diseases. Studies on genetic, molecular, and cellular mechanisms of sclerosteosis and van Buchem disease revealed a role for sclerostin in bone homeostasis, which led to the development of the sclerostin antibody to treat osteoporosis and other bone degenerative diseases. The mechanism of many other rare bone diseases and the role of the osteocyte in the development of such conditions still needs to be investigated. In this review, we mainly discuss the knowledge obtained during the last 30 years on the role of the osteocyte in rare bone diseases. We speculate about future research directions to develop novel therapeutic drugs targeting osteocyte functions to treat both common and rare bone diseases.

Management of Catastrophic Proximal Junctional Failure Following Spinal Deformity Correction in an Adult with Osteogenesis Imperfecta: Case Report and Technical Note

BACKGROUND

Proximal junctional failure (PJF) is a major and sometimes devastating problem following adult spinal deformity (ASD) correction surgery. Common consensus still lags on guidelines for preventing and managing these complications. Surgical treatment of scoliosis in the presence of osteogenesis imperfecta (OI) in the pediatric population is well described. The complication rates are unusually higher in this special subset of patients owing to poor quality of bone. There is a paucity of literature focusing on surgical techniques, strategies, and problems involved in the management of ASD associated with OI.

CASE DESCRIPTION

We report a 59-year-old female with type 1 OI and adult scoliosis who underwent T10-to-pelvis fusion for ASD according to the principles of adult deformity correction. At a 1-year follow-up, she presented with asymptomatic proximal junctional kyphosis of 45° and 2 weeks later had PJF along with spinal cord injury after a fall. On computed tomography scan, kyphosis was increased to 60° at T9-T10. She underwent decompression and revision deformity correction using quadruple rods, with extension of instrumentation to T2 with soft landing using rib bands. At a 4-year follow-up, she had a good functional outcome after revision surgery.

CONCLUSIONS

This is the first report of successful management of PJF following ASD correction in the presence of OI using this technique. Suboptimal hold of implants due to poor bone quality must be at the focus of any surgical planning for these patients. All possible strategies to prevent PJF must be considered when planning the deformity correction in adults with OI.

Scoliosis and Cardiopulmonary Outcomes in Osteogenesis Imperfecta Patients

STUDY DESIGN

Retrospective clinical study of individuals with osteogenesis imperfecta (OI).

OBJECTIVE

To assess the relationship between severity of scoliosis and pulmonary function, and to assess the relationship between restrictive lung disease and self-reported quality of life in individuals with OI.

SUMMARY OF BACKGROUND DATA

OI is a heritable connective tissue disorder characterized by osteopenia and a predisposition to fracture. Respiratory insufficiency is a leading cause of mortality. Literature on pulmonary function in this population has shown a negative correlation between percent-predicted vital capacity and severity of scoliosis. However, it has been suggested that decreased pulmonary function in OI may be due to intrinsic pulmonary disease, in addition to the impact of vertebral compression fractures and scoliosis.

METHODS

Anterior-posterior spine radiographs and pulmonary function tests from 30 individuals with OI were reviewed. Radiographs were evaluated for scoliosis, defined as a curve ≥ 10°. If more than one curve was present, the largest curve was used. Pulmonary function was defined as the forced expiratory volume in 1 second (FEV1)/forced vital capacity (FVC) ratio. Restrictive pulmonary disease was defined as FEV1/FVC > 80%, while obstructive disease was defined as FEV1/FVC < 70%. Bivariate correlation analysis was performed, using Spearman rho correlation coefficient (P < 0.05). Quality of life was assessed by SF-36.

RESULTS

The mean age was 27.6 years (range: 12-42 yrs). 57.6% were female. OI type IV was the most common (46.7%), followed by OI type III (33.3%), OI type I (10%), OI type IX (6.67% each), and OI type VIII (3.33%). Pulmonary comorbidity was present in 40% of individuals, while 6.67% had a cardiac comorbidity. The correlation between scoliosis and pulmonary function was weak and not significant (R = -0.059, P = 0.747).

CONCLUSION

Pulmonary function is not significantly correlated with scoliosis, supporting the hypothesis that decreased pulmonary function is intrinsic to OI and/or chest wall deformities, rather than secondary to scoliosis.

LEVEL OF EVIDENCE

4.

Radiation exposure in adult and pediatric patients with osteogenesis imperfecta

Diagnostic radiographs, computed tomography (CT), nuclear medicine studies, and intraoperative fluoroscopy durations were analyzed for radiation exposure. Cumulative and yearly effective ionizing radiation doses, cumulative background radiation, and total radiograph studies were compared between pediatric and adult populations. In 24 patients with 1,246 imaging studies (average 5.5 years longitudinal treatment duration), the mean estimated cumulative effective radiation dose per patient was 30.0 mSv (range 2.3-115.0), with an average yearly dose of 4.9 mSv (range 0.4-24.8). Pediatric patients had significantly more radiograph studies per year than adults and greater average yearly effective radiation doses.

Cyclic pamidronate treatment for osteogenesis imperfecta: Report from a Brazilian reference center

Treatment of moderate and severe forms of osteogenesis imperfecta (OI) with cyclic pamidronate at the Reference Center for OI Treatment in Southern Brazil was studied. A retrospective cohort study was conducted from 2002 to 2012. Data were obtained during inpatient (drug infusion) and outpatient care. Clinical data, including the presence of blue sclerae, dentinogenesis imperfecta, history and site of the fractures, biochemical data, including calcium, phosphorus, and alkaline phosphatase levels, were systematically collected. Bone mineral density (BMD) was measured using dual energy X-ray absorptiometry (DXA). Forty-five patients (26 females) were included in the study, and the age of the patients at the time of diagnosis ranged from 1 to 144 months, with a median age (p25-p75) of 38 (5-96) months. Most cases presented OI-4 (51.1%), and the median age of the patients at the start of treatment was 3.3 years (25-75 percentiles: 0.5 - 8.7 years). Twenty-four patients (54.5%) had some adverse events or intercurrences during treatment, and the treatment compliance mean was 92.3% (± 10.7). The treatment with intravenous pamidronate has shown to be safe, well-tolerated, and effective in regard to the improvement of BMD and the reduction of the number of fractures in children and adolescents with OI.

Splice receptor-site mutation c.697-2A>G of the COL1A1 gene in a Chinese family with osteogenesis imperfecta

Osteogenesis imperfecta (OI) is a genetic disorder characterized by bone fragility and blue sclerae, which are mainly caused by a mutation of the COL1A1 or COL1A2 genes that encode type I procollagen. Mutations in the splice site of type I collagen genes are one of the mutations that cause OI and usually lead to a mild or moderate OI phenotype. A heterozygous A to G point mutation in intron 9 at the -2 position of the splice receptor site of COL1A1 was identified in a family with type I or IV OI. Three affected individuals in four generations of one family all presented with several clinical symptoms. They all had pectus carinatum, flat feet, gray-blue sclerae, and normal stature, teeth, hearing, and vision. Forearm fractures, small joint dislocations, and muscle weakness were all present in the patient's father and grandmother, who presented with a moderate type IV phenotype. The 10-year-old proband with type I OI had suffered a fracture twice, but had no history of joint dislocation or skin hyperextensibility. Charting the family helped to identify clinical symptoms in patients with mutations at the N-terminal of type I collagen genes.

COL1A2 p.Gly1066Val variant identified in a Han Chinese family with osteogenesis imperfecta type I

Background

Osteogenesis imperfecta (OI), a genetically determined connective tissue disorder, is characterized by increased bone fragility and reduced bone mass. Clinical presentation severity ranges from very mild types with nearly no fractures to intrauterine fractures and perinatal lethality. It can be accompanied by blue sclerae, dentinogenesis imperfecta (DI), hearing loss, muscle weakness, ligament laxity, and skin fragility. This study sought to identify pathogenic gene variants in a four‐generation Han Chinese family with OI type I.

Methods

In order to unveil the molecular genetic factors underlying the disease phenotype, whole exome sequencing in a member, with OI type I, of a Han Chinese family from Hunan, China was performed. The variant identified by whole exome sequencing was further tested by Sanger sequencing in the family members.

Results

A heterozygous missense variant (NM_000089.3: c.3197G>T; NP_000080.2: p.Gly1066Val) in the collagen type I alpha 2 chain gene (COL1A2) was identified in four patients. It co‐segregated with the disease in the family.

Conclusion

The sequence variant may be a disease‐causing factor resulting in abnormal type I procollagen synthesis and leading to OI type I. This finding has significant implications for genetic counseling and clinical monitoring of high‐risk families and may be helpful for understanding pathogenic mechanism of OI and developing therapies.

Osteogenesis imperfecta and therapeutics

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.

Whole exome sequencing identifies an AMBN missense mutation causing severe autosomal-dominant amelogenesis imperfecta and dentin disorders

Tooth development is a complex process that involves precise and time-dependent orchestration of multiple genetic, molecular, and cellular interactions. Ameloblastin (AMBN, also named “amelin” or “sheathlin”) is the second most abundant enamel matrix protein known to have a key role in amelogenesis. Amelogenesis imperfecta (AI [MIM: 104500]) refers to a genetically and phenotypically heterogeneous group of conditions characterized by inherited developmental enamel defects. The hereditary dentin disorders comprise a variety of autosomal-dominant genetic symptoms characterized by abnormal dentin structure affecting either the primary or both the primary and secondary teeth. The vital role of Ambn in amelogenesis has been confirmed experimentally using mouse models. Only two cases have been reported of mutations of AMBN associated with non-syndromic human AI. However, no AMBN missense mutations have been reported to be associated with both human AI and dentin disorders. We recruited one kindred with autosomal-dominant amelogenesis imperfecta (ADAI) and dentinogenesis imperfecta/dysplasia characterized by generalized severe enamel and dentin defects. Whole exome sequencing of the proband identified a novel heterozygous C-T point mutation at nucleotide position 1069 of the AMBN gene, causing a Pro to Ser mutation at the conserved amino acid position 357 of the protein. Exfoliated third molar teeth from the affected family members were found to have enamel and dentin of lower mineral density than control teeth, with thinner and easily fractured enamel, short and thick roots, and pulp obliteration. This study demonstrates, for the first time, that an AMBN missense mutation causes non-syndromic human AI and dentin disorders.

A mutation on a gene involved in healthy tooth development may cause both enamel and dentin disorders. The ameloblastin enamel protein, and its associated gene, AMBN, play vital roles in enamel formation and tooth remodelling. Mutations on AMBN can cause amelogenesis imperfecta (AI), a genetic and hereditory condition resulting in enamel defects and severe tooth decay. Now, Fu Xiong and Bu-Ling Wu at Southern Medical University in Guangzhou, China, and co-workers have identified an AMBN mutation found in both enamel and dentin defect disorders. The researchers analyzed extracted teeth from a Chinese patient with both AI and a severe dentin disorder, along with teeth from affected and non-affected members of the same family, and compared the results with a control group. They identified a rare mutation on AMBN common to all affected individuals.

Sleep-disordered breathing in paediatric setting: existing and upcoming of the genetic disorders

Childhood obstructive sleep apnea syndrome (OSAS) is characterized by anatomical and functional upper airway abnormalities as pathophysiological determinants, and clinical symptoms are frequently clear. OSAS is widely described in rare genetic disorders, such as achondroplasia, Down syndrome, Prader-Willi syndrome, Pierre Robin sequence, and mucopolysaccharidosis. Craniofacial and upper airway involvement is frequently morbid conditions. In children with genetic diseases, the clinical symptoms of OSAS are often slight or absent, and related morbidities are usually more severe and can be observed at any age. The present review is aimed to updating the discoveries regarding OSAS on Achondroplasia, Down syndrome, Prader-Willi syndrome, Pierre Robin sequence, Sickle cell disease, or encountered in our clinical practice (Ehlers-Danlos syndrome, Ellis-van Creveld syndrome, Noonan syndrome). Two additional groups of genetic disorders will be focused (mucopolysaccharidoses and osteogenesis imperfecta). The flowing items are covered for each disease: (I) what is the pathophysiology of OSAS? (II) What is the incidence/prevalence of OSAS? (III) What result from the management and prognosis? (IV) What are the recommendations? Considering the worries of OSAS, such as inattention and behavioural problems, daytime sleepiness, failure to thrive, cardiological and metabolic complications, the benefit of a widespread screening and the treatment in children with genetic diseases is undoubtful. The goals of the further efforts can be the inclusion of various genetic diseases into guidelines for the screening of OSAS, updating the shreds of evidence based on the research progression.

A comparative study of quality of life, functional and bone outcomes in osteogenesis imperfecta with bisphosphonate therapy initiated in childhood or adulthood

Bisphosphonates have been used for treatment of bone fragility disorders for over 25 years to increase bone mineral density (BMD). Anecdotally, bisphosphonate-treated Osteogenesis Imperfecta (OI) has a different trajectory to the natural history of untreated OI in terms of fracture incidence, quality of life and physical function, with minimal published evidence to support this clinical observation. This study describes functional outcomes of a cohort of adults with OI, stratified according to severity and treated with intravenous bisphosphonates as children. Reported outcomes included fracture incidence before and after puberty, mobility and BMD outcomes of this cohort. The cohort was compared to adults with OI who were never treated as children. All participants completed four questionnaires: a study specific questionnaire addressing fracture and treatment history, WHOQOL-BREF (quality of life), SF-36 (musculoskeletal function) and IPAQ (physical activity), and medical records were reviewed. Fifty-two adults with OI (80% response rate) completed the questionnaires; 33 of whom were treated with bisphosphonates in childhood. The childhood treated cohort had higher lumbar spine BMD than the adult treated cohort (z-score - 0.4 at mean age 21.3 years versus -2.1 at mean age 40.9 years; p = 0.003). Pre-pubertal fracture incidence was reduced for all severities of OI in the childhood treated cohort (less severe OI, p = 0.01; more severe OI, p < 0.001), but post-pubertal fracture incidence was higher for less severe OI (p < 0.001). In less severe OI, childhood treated individuals had higher levels of physical activity (p = 0.004) and physical functioning (p = 0.01) than adult treated individuals. Incidence of scoliosis was not different between cohorts. There were no differences in quality of life scores between the two cohorts. Improvements in BMD do not appear to influence the prevalence of scoliosis. Results suggest that treatment with bisphosphonates at an earlier age improves physical activity, particularly in less severe forms of OI but may not alter quality of life.

Severely Impaired Bone Material Quality in Chihuahua Zebrafish Resembles Classical Dominant Human Osteogenesis Imperfecta

Excessive skeletal deformations and brittle fractures in the vast majority of patients suffering from osteogenesis imperfecta (OI) are a result of substantially reduced bone quality. Because the mechanical competence of bone is dependent on the tissue characteristics at small length scales, it is of crucial importance to assess how OI manifests at the micro- and nanoscale of bone. In this context, the Chihuahua (Chi/+) zebrafish, carrying a heterozygous glycine substitution in the α1 chain of collagen type I, has recently been proposed as a suitable animal model of classical dominant OI, showing skeletal deformities, altered mineralization patterns, and a smaller body size. This study assessed the bone quality properties of Chi/+ at multiple length scales using micro-computed tomography (micro-CT), histomorphometry, quantitative back-scattered electron imaging, Fourier-transform infrared spectroscopy, nanoindentation, and X-ray microscopy. At the skeletal level, the Chi/+ displays smaller body size, deformities, and fracture calli in the ribs. Morphological changes at the whole bone level showed that the vertebrae in Chi/+ had a smaller size, smaller thickness, and distorted shape. At the tissue level, Chi/+ displayed a higher degree of mineralization, lower collagen maturity, lower mineral maturity, altered osteoblast morphology, and lower osteocyte lacunar density compared to wild-type zebrafish. The alterations in the cellular, compositional, and structural properties of Chi/+ bones bear an explanation for the impaired local mechanical properties, which promote an increase in overall bone fragility in Chi/+. The quantitative assessment of bone quality in Chi/+ thus further validates this mutant as an important model reflecting osseous characteristics associated with human classical dominant OI. © 2018 American Society for Bone and Mineral Research.

Percutaneous screw fixation of fractured neck of femur in a teenage girl with osteogenesis imperfecta. A case report

INTRODUCTION

Neck of femur fracture in osteogenesis imperfecta is rarely reported. The management is uncertain and always reported as difficult. Clinical outcomes are not well described.

CASE PRESENTATION

A teenage girl, who is known to have osteogenesis imperfecta, sustained neck of femur fracture in the presence of a previously inserted implant. She was treated by percutaneous screw fixation. In both immediate and long term follow up, our patient had satisfactory outcome and return to pre-fracture functional status.

DISCUSSION

Dealing with fragility fracture in small abnormal hips is challenging especially, in the presence of a retained implant in- situ. Intra-operative difficulty were encountered during positioning, reduction, and screw insertion attempt.

CONCLUSION

This rare case illustrates the anticipated difficulties in managing neck of femur fracture in osteogenesis imperfect patients. It also emphasize on the importance of surgical fixation to control pain and allow for healing in anatomically functional position.

Pain and quality of life of children and adolescents with osteogenesis imperfecta over a bisphosphonate treatment cycle

The objective was to describe the pain and quality of life among children and adolescents with any osteogenesis imperfecta (OI) type over one intravenous bisphosphonate treatment cycle from a child and parental perspective. A prospective, observational study was conducted, where children and adolescents evaluated their pain intensity, location, and quality, as well as quality of life before, 1 week after treatment, and 6 months later. Quality of life was also evaluated from the parental perspective at the same three time points. Thirty-three child/parent dyads participated. The results showed that pain intensity on the 0-10 self-report scale after the Zoledronate infusion (median = 0, range = 0-6) was not different from pre (median = 2, range = 0-10) and 6-months post-scores (median = 2, range = 0-8) (p = 0.170). Children and adolescents with OI reported experiencing pain mainly in the ankles and the anterior and posterior shoulders. They selected evaluative pain descriptors such as uncomfortable (n = 16, 48%) and annoying (n = 13, 39%). Children and adolescents' functioning and quality of life did not change significantly across the bisphosphonate treatment cycle (p = 0.326), parents perceived an improvement immediately after the treatment compared to before (p = 0.016).

CONCLUSION

Children and adolescents with OI experience mild, yet complex pain localized across several body areas. There is little fluctuation in the pain intensity and functioning of children with OI undergoing bisphosphonate treatment. What is Known: • Acute and chronic musculoskeletal pain remains a major issue in OI. • Pain has a negative impact on quality of life. What is New: • New and unpublished methods and findings describing the pain and quality of life of children and adolescents with OI over one intravenous bisphosphonate treatment cycle from a child- and parental-proxy perspective. • Children and adolescents with OI experience pain intensity that is mild, yet complex in quality and localized across several body areas.

Insight into the Pathology of a COL1A1 Signal Peptide Heterozygous Mutation Leading to Severe Osteogenesis Imperfecta

Osteogenesis imperfecta or "brittle bone disease" is a congenital disorder of connective tissue causing the bone to break easily. Around 85-90% of cases are due to autosomal dominant mutations in the genes encoding type I collagen, the major organic component of bone. Genotype-phenotype correlations have shown that quantitative defects of collagen type I lead to mild OI, whereas structural defects show a wide clinical range from mild to perinatal lethal. This may partially be explained by the type of amino acid substitution and the relative location in the domain structure. To fully understand the variability of the clinical manifestation and the underlying pathomechanisms, further investigations are required. Here we provide the first biochemical characterization of a mutation at the signal peptide cleavage site of COL1A1, a domain not yet characterized. By steady-state analysis, we observed reduced production of collagen type I. Furthermore, by pulse-chase analysis we detected delayed secretion and partial intracellular retention of collagen I. In the cellular fraction, the electrophoretic migration was abnormal; however, secreted type I collagen showed a normal migration pattern. The intracellular retention of collagen I was confirmed by immunofluorescent staining. Moreover, transmission electron microscopy of cultured fibroblasts revealed enlargement of ER cisternae. These results further support the hypothesis that mechanisms interfering with ER integrity play an important role in the pathology of severe OI.