Osteogenesis imperfecta: an update on clinical features and therapies

Disrupted maxillofacial, cardiovascular, and nervous development in washc5 knockout Zebrafish: Insights into 3C syndrome

3C syndrome features craniofacial, nervous, and cardiovascular malformations. WASHC5 gene mutations may underline this syndrome, but the pathogenicity and underlying mechanism remain undetermined. We analyzed the expression pattern of the washc5 gene in zebrafish using whole-body in situ hybridization and generated a zebrafish model with washc5 gene knockout using CRISPR/Cas9 technology. Homozygous zebrafish exhibited high mortality, retarded growth, lighter stripes, and reduced pigmentation around the pupils. In the maxillofacial region, homozygotes displayed a shortened and tilted maxilla and delayed ossification of bones. In the heart, homozygous zebrafish showed a decreased heart rate, increased ventricular area, disorganized ventricular muscle fibers, mitochondrial swelling, Golgi lysis, and endoplasmic reticulum (ER) lysis in ventricular myocytes. The mRNA levels of nppb and myh7 were significantly increased. In the nervous system, homozygotes displayed bradykinesia and impaired neuronal development. qRT-PCR analysis revealed downregulation of col1a2, col1a1a, col1a1b, sp7, and msx2b (osteogenic factors and regulators of maxillofacial skeletal development) and abnormal expression of alpk2, alpk3b, actc2 (cardiac development factors), as well as tsen54, exosc8, and exosc9 (cerebellar development factors). Enrichment analysis of differentially expressed genes and proteins indicated involvement in ER-related processes. The washc5 knockout zebrafish model exhibits phenotypic similarities to human 3C syndrome, suggesting that mutations of this gene may play a pathogenic role in the syndrome. The mechanism of the washc5 gene in 3C syndrome may be associated with disturbances in ER homeostasis, providing insights into potential gene therapy strategies.

The effects of FOXC2-gene-manipulated human periodontal ligament stem cells on bone regeneration of craniofacial bone defect

The progress and development of bone tissue engineering technology has brought new hope for the repair of oral and maxillofacial bone defects. As one of the ideal seed cells, the induction of human periodontal ligament stem cells (hPDLSCs) into osteoblasts has become a focus in current research. Forkhead box C2 (FOXC2) may be a good candidate gene for bone regeneration. Therefore, the aim of this study was to verify the role of FOXC2 in hPDLSCs osteogenesis and genetically-manipulate seed cells based on FOXC2 gene for enhancing their bone regeneration potentials. The hPDLSCs models with down-regulated and up-regulated expression of FOXC2 were constructed by lentivirus transfections. ALP staining, alizarin red staining, qRT-PCR, WB analysis and histological staining were used to verify the function of FOXC2 in regulating osteogenic differentiation of hPDLSCs. Finally, through transcriptome sequencing and qRT-PCR verification, the downstream core genes, and possible mechanism of FOXC2 were speculated. All data were presented as means ± standard deviations (SDs). P values less than 0.05 were considered statistically significant. GraphPad PRISM software (version 9.0; La Jolla, CA, USA) was used. The research results suggest that FOXC2 gene is involved in the regulation of osteogenic differentiation of hPDLSCs which may be related to promoting extracellular matrix interaction, cell adhesion and collagen formation. hPDLSCs with FOXC2 up-regulation are expected to be used as gene-enhanced seed cells in bone tissue engineering.

Mineralised bone properties in a child with recessive osteogenesis imperfecta type XIV and in a conditional Tmem38b knockout murine model (Runx2-Cre; Tmem38bfl/fl)

INTRODUCTION

OI type XIV is caused by variants in the TMEM38B gene, encoding for the ubiquitously expressed endoplasmic reticulum trimeric intracellular cation channel type B (TRIC-B), causing disruptions in calcium homeostasis and collagen synthesis. Patients with OI type XIV present with a highly variable clinical phenotype, ranging from asymptomatic to severe. We present here data from a 6 year clinical follow-up of two affected siblings and bone tissue characterisation obtained during corrective surgery from one of the patients, as well as tibiae from a novel Tmem38b conditional knockout murine model (Runx2-Cre; Tmem38bfl/fl).

METHODS

Clinical examinations of the patients include bone mineral density (BMD) measurements using dual-energy x-ray absorptiometry (DXA) scanning and gait analyses. Quantitative backscattered electron imaging (qBEI) was used to investigate bone mineralisation density distribution (BMDD) and osteocyte lacunae properties, and confocal laser scanning microscopy was used to quantify the osteocyte lacuno-canalicular network (OLCN) in both human and murine specimens.

RESULTS

Both patients (P1, P2) presented with muscular hypotension, fatigue, progression of lower limb deformities, and fractures. BMDD of the osteonal bone region of the tibia and fibula specimens obtained from P1 revealed no significant shift towards higher mineral content as seen in "classical" OI. Osteocyte lacunae porosity was elevated and analyses of the OLCN revealed a reduction in canalicular density and lacunar degree. Runx2-Cre; Tmem38bfl/fl mice exhibited a very severe skeletal phenotype, with 10/12 of the tibiae showing evidence of fractures, bone deformations, or calluses. In contrast to the patient samples, both the cortex and metaphysis of mutant mice demonstrated a significant increase in the average mineral content (CaMean) and the peak of the distribution (CaPeak), as well as in osteocyte lacunae porosity (P < 0.0001), whereas canalicular density (P < 0.0001), and lacunar degree (P = 0.0004) were decreased.

CONCLUSION

While Runx2-Cre; Tmem38bfl/fl mice exhibit hypermineralisation of the bone matrix, this is not apparent in bone specimens obtained from the OI type XIV patient. However, both human and murine bone tissue with absence of TRIC-B demonstrate the same abnormalities of the osteocyte lacunae porosity and osteocyte lacuno-canalicular network, indicating disruption to the OLCN which is likely a general hallmark of OI bone.

A Novel Homozygous Synonymous Variant in CCDC134 as a Cause of Osteogenesis Imperfecta Type XXII

Osteogenesis imperfecta (OI) is a heterogeneous group of rare, inherited connective tissue disorders. It includes over 20 defined subtypes, each of which is associated with distinct causative genes that are listed in the Online Mendelian Inheritance in Man (OMIM) database. Type XXII OI (OI 22) is caused by a homozygous variant in the coiled-coil domain containing 134 (CCDC134) gene, which is located on chromosome 22q13. OI, which is associated with CCDC134, is extremely rare with only five cases reported worldwide. All known cases involve the c.2 T > C (p. Met1Thr) homozygous missense variant in the CCDC134 gene. We present the case of a 13-year-old Chinese girl with non-union fracture, short stature and specific radiographic findings, which include scoliosis, pelvic tilt, thin clavicles, ribs, and limbs. Whole exome sequencing revealed a novel, homozygous c.492G > C (p. Leu164=) variation in the CCDC134 gene. RNA sequencing (RNA-seq) analysis identified this variant as an abnormal splicing variant that causes the deletion of Exon 5, which result in the observed disease phenotype. This case demonstrates the clinical phenotype of OI 22 associated with the c.492G > C (p. Leu164=) novel synonymous variation in the coding region of the CCDC134 gene in a female patient. This is the first reported case of OI 22 in the Chinese population, the sixth reported worldwide and the fourth reported genotype for diseases associated with a CCDC134 variant. It also enriches the global clinical phenotype spectrum of OI 22 patients.

The Spectra of Pathogenic Variants and Phenotypes in a Chinese Cohort of 298 Families with Osteogenesis Imperfecta

Background: Osteogenesis imperfecta (OI) is marked by clinical and genetic heterogeneity, and the genotype-phenotype correlation remains not very clear. We conducted a clinical and genetic study in a Chinese OI cohort to determine the spectra of phenotypes and pathogenic variants. Methods: In this study, 298 Chinese families were recruited from 2019 to 2024. Clinical phenotypes including fractures, short stature, skeletal deformities, blue sclera, dentinogenesis imperfecta, and hearing loss were recorded and analyzed. Next-generation sequencing combined with PCR-based techniques was used to detect candidate pathogenic variants. Variant pathogenicity was evaluated via conservation analysis, bioinformatics analysis, and functional studies at the cellular level. In this OI cohort, the spectra of pathogenic variants, clinical phenotypes, and genotype-phenotype correlations were analyzed. Results: Our OI cohort included 71 type I (23.83%), 122 type III (40.94%), 90 type IV (30.20%), and 15 type V (5.03%) probands. The cohort consisted of 196 children (65.77%) and 102 adults (34.23%). For the first time, phenotypic differences between different age groups were confirmed. In total, we identified 231 variants, including 47 novel pathogenic variants. Notable variants include two atypical splicing variants, one small deletion, two small duplications, one gross deletion, and one gross duplication. New genotype-phenotype correlations were observed: patients with SERPINF1 variants had the highest fracture frequency, followed by those with WNT1 variants, compared to patients with other gene variants. Conclusions: We performed the clinical and genetic analysis in a large Chinese OI cohort. The expanded spectra of genetic variants and clinical phenotypes were constructed by identifying 47 novel pathogenic variants and summarizing the skeletal and extra-skeletal manifestations. The current paper will provide important evidence for the precise diagnosis of the disease.

Lower limb deformity and gait deviations of osteogenesis imperfecta

BACKGROUND

Osteogenesis imperfecta is a rare genetic disorder characterized by complex lower limb deformities, resulting in various gait limitations. This study aimed to (1) investigate the incidence and association between radiographic changes and gait impairment; (2) propose a lower limb deformity index to quantify deformity severity as well as gait performance.

METHODS

Bilateral X-ray images and 3D gait analysis results were assessed retrospectively from 48 patients with osteogenesis imperfecta. Multivariate linear regression was used to investigate the contribution of each deformity to gait performance. Eight scoring approaches of the proposed index, calculated from radiographic changes, were evaluated by their linear relationship to gait deviation.

RESULTS

Patients with osteogenesis imperfecta had high incidence of anterolateral bowing of femur, and anteromedial bowing of tibia, along with abducted hip, varus knee, hip flexion and ankle dorsiflexion deformities. Their maximum joint kinematics and kinetics were less than healthy controls, which was consistent with their major deformities. However, multivariate linear regression indicated a limited contribution from each deformity to gait deviation (only mechanical axis deviation out of 14 radiographic measures showed significance). Remarkably, our proposed index presented a significant linear correlation to gait deviation (Correlation coefficient: -0.650; R square: 0.423; F value: 33.719, p < 0.001).

CONCLUSIONS

This study preliminary demonstrated the association between lower limb deformities and gait deviations of patients with osteogenesis imperfecta and proposed a lower limb deformity index to quantify the deformity severity that reflects gait performance.

Comprehensive Review of Osteogenesis Imperfecta: Current Treatments and Future Innovations

Osteogenesis imperfecta (OI) is a rare genetic disorder characterized by bone fragility due to reduced bone quality, often accompanied by low bone mass, recurrent fractures, hearing loss, skeletal abnormalities, and short stature. Pathogenic variants in over 20 genes lead to clinical and genetic variability in OI, resulting in diverse symptoms and severity. Current management involves a multidisciplinary approach, including antiresorptive medications, physiotherapy, occupational therapy, and orthopedic surgery, which provide symptomatic relief but no cure. Advancements in gene therapy technologies and stem cell therapies offer promising prospects for long-lasting or permanent solutions. This review provides a comprehensive overview of OI's classification, pathogenesis, and current treatment options. It also explores emerging biotechnologies for stem cells and gene-targeted therapies in OI. The potential of these innovative therapies and their clinical implementation challenges are evaluated, focusing on their imminent success in treating bone disorders.

TBS as a complementary tool for assessing vertebral fractures and spinal deformity in children and adolescents with osteogenesis imperfecta

This study evaluated trabecular bone score (TBS) for assessing vertebral fractures and spinal deformity in children and adolescents with osteogenesis imperfecta (OI). TBS showed superior performance in identifying vertebral fractures compared to areal bone mineral density (aBMD), especially in patients without densitometric osteoporosis, suggesting its potential for monitoring vertebral fractures and spinal deformity risk.

BACKGROUND

TBS, derived from a textural greyscale analysis of lumbar spine dual-energy X-ray absorptiometry (DXA) images, offers a non-invasive and indirect evaluation of bone microarchitecture. This method potentially enhances the assessment of skeletal phenotypes beyond the scope of aBMD. We aim to explore the utility of TBS in assessing vertebral fractures and spinal deformity in children and adolescents with OI.

METHODS

In this cross-sectional study, 153 children and adolescents with OI were enrolled. DXA was used to measure TBS and aBMD, and their Z-scores were calculated based on reference values for BMD and TBS in normal children and adolescents with the same age and sex. Lateral thoracolumbar films were used to evaluate vertebral fractures and calculate the spine deformity index (SDI). The accuracy of TBS and aBMD for identifying vertebral compression fractures (VCFs) was assessed using area under the curve (AUC).

RESULTS

TBS Z-score was negatively correlated with the age of children with OI (r =  - 0.435, P < 0.001) and was positively correlated to aBMD Z-score at the lumbar spine and femoral neck (both P < 0.01), even after adjusting for confounding factors. TBS Z-score was as effective as lumbar spine aBMD Z-score in discriminating VCFs (AUC, 0.667 vs 0.666, P > 0.05). Notably, in patients without densitometric osteoporosis, TBS Z-score demonstrated superior discriminative power for VCFs compared to lumbar spine aBMD Z-score (AUC, 0.719 vs 0.545, P < 0.05). In this population, only the TBS Z-score (r =  - 0.358, P < 0.05), rather than the lumbar spine aBMD Z-score, was negatively correlated with the SDI.

CONCLUSION

TBS has a close correlation with bone mineral density in children and adolescents with OI. In patients without densitometric osteoporosis, the Z-score of TBS is more effective than that of bone mineral density in assessing VCFs and spinal deformity, highlighting the potential of TBS in evaluating the risk of VCFs and monitoring the progression of spinal deformity.

Cardiovascular disease in adults with osteogenesis imperfecta: clinical characteristics, care recommendations, and research priorities identified using a modified Delphi technique

Osteogenesis imperfecta (OI) is a multisystem disorder most often caused by pathogenic variants in genes that encode type I collagen. Type I collagen is abundant not only in bone but also in multiple tissues including skin, tendons, cornea, blood vessels, and heart. Thus, OI can be expected to affect cardiovascular system, and there are numerous reports of cardiovascular disease (CVD) in people with OI. However, there is no consensus on how CVD in OI should be assessed or managed. To fill this gap, a multidisciplinary group was convened to develop clinical guidance. The work included a systematic review of the available literature and, using a modified Delphi approach, the development of a series of statements summarizing current knowledge. Fourteen clinical recommendations were developed to guide clinicians, patients, and stakeholders about an approach for CVD in adults with OI. This paper describes how the work was conducted and provides the background and rationale for each recommendation. Furthermore, we highlight knowledge gaps and suggest research priorities for the future study of CVD in OI.

Resilience and coping: a qualitative analysis of cognitive and behavioral factors in adults with osteogenesis Imperfecta

PURPOSE

The aim of this qualitative study was to investigate resilience among adults with Osteogenesis Imperfecta (OI).

MATERIALS AND METHODS

Semi-structured interviews were conducted with 15 adults with OI. Transcripts were coded and subsequently abstracted, yielding themes specific to resilience and coping. Interview guides covered broad topics including pain challenges specific to OI, mental health issues related to OI, and priorities for future interventions for individuals with OI.

RESULTS

Participants described resilience in the context of OI as the ability to grow from adversity, adapt to challenges resulting from OI-related injuries, and find identities apart from their condition. Psychological coping strategies included acceptance, self-efficacy, cognitive reframing, perspective-taking, and positivity. Behavioral factors that helped participants develop resilience included developing new skills, pursuing meaningful goals, practicing spirituality, and seeking external resources such as psychotherapy, education, and connection with community.

CONCLUSION

Having identified how adults with OI define resilience and the strategies they use to cope, we can now develop interventions and guide healthcare providers in improving psychological wellbeing in this population.

Mastication and electrical activation in the masseter and anterior temporalis muscles of children and adolescents with osteogenesis imperfecta

PURPOSE

to characterize mastication and electrical activation of the masseter and anterior temporalis muscles in children and adolescents with osteogenesis imperfecta (OI), and relate results to guided occlusion and occlusal interference.

METHODS

This observational, analytical cross-sectional study included 22 subjects divided into mild OI (MOI) (type 1) (n=15) and moderate-to-severe OI (MSOI) (types 3, 4, and 5) (n=7) groups. The Orofacial Myofunctional Evaluation with Scores (OMES) form was used to evaluate the clinical aspects of mastication. Surface electromyography was performed on the masseter and anterior temporalis muscles at rest for 10 seconds and during maximum intercuspation, spontaneous chewing, and instructed chewing on the right and left sides. Additionally, the activation index and muscle symmetry were measured.

RESULTS

a preferentially unilateral chewing pattern was observed in 12 (54.5%) participants. Masticatory patterns did not influence electrical activation during any of the tasks, nor did occlusal guidance during maximum intercuspation or mastication. The percentage of muscle activation during maximal intercuspation approached half of the total activation during spontaneous chewing. In muscle activation indices, the MSOI group presented more atypical scores, while the MOI group scores seemed to be in line with reference values. The symmetry indices seemed to correspond to reference values, but the standard deviation and minimum and maximum values pointed to asymmetric results.

CONCLUSION

This study found that the OI population presented muscle imbalances, but the results did not allow us to define one pattern of change.

Gelatin/Poly (Lactic-Co-Glycolic Acid)/Attapulgite Composite Scaffold Equipped with Teriparatide Microspheres for Osteogenesis in vitro and in vivo

Background

Given the risks associated with autologous bone transplantation and the limitations of allogeneic bone transplantation, scaffolds in bone tissue engineering that incorporate bioactive peptides are highly recommended. Teriparatide (TPTD) plays a significant role in bone defect repair, although achieving controlled release of TPTD within a bone tissue engineering scaffold remains challenging. This work reports a new approach for treatment of teriparatide using a water-in-oil-in-water (w/o/w) microspheres be equipped on gelatin (GEL)/Poly lactic-glycolic acid (PLGA)/attapulgite (ATP) scaffold.

Methods

In this study, TPTD microspheres were prepared by the water-in-oil-in-water (w/o/w) double emulsion technique and GEL/PLGA/ATP composite scaffolds with different setups were prepared by salt leaching method. Both microspheres and scaffolds underwent physicochemical characterization. Mouse bone mesenchymal stem cells (BMSCs) were co-cultured with extracts from the microspheres and scaffolds to evaluate cell proliferation and osteogenesis. Four weeks post-implantation, the effectiveness of the scaffolds containing microspheres for repairing skull defects in mice was assessed.

Results

Both TPTD microspheres and the GEL/PLGA/ATP scaffold significantly enhanced the proliferation and osteogenic differentiation of BMSCs. Markers of osteoblast activity, including COL1, RUNX2, OCN, and OPN, were markedly up-regulated. Further, micro-CT, histological, and immunohistochemical analyses revealed extensive new bone formation on the scaffold.

Conclusion

The GEL/PLGA/ATP composite scaffold, equipped with TPTD microspheres, demonstrates significant potential for use in bone tissue engineering, providing an effective option for bone regeneration and repair in clinical applications.

Col1A1 as a new decoder of clinical features and immune microenvironment in ovarian cancer

Backgrounds

Collagen type I alpha 1 chain (COL1A1) is a key protein encoding fibrillar collagen, playing a crucial role in the tumor microenvironment (TME) due to its complex functions and close association with tumor invasiveness. This has made COL1A1 a focal point in cancer biology research. However, studies investigating the relationship between COL1A1 expression levels and clinical characteristics of ovarian cancer (OC) remain limited.

Methods

This study integrated resources from publicly available online databases and immunohistochemistry (IHC) techniques to analyze and validate COL1A1 expression in OC tissues, and evaluated its potential association with clinical features in OC patients. The prognostic value of COL1A1 was assessed using Kaplan-Meier (KM) survival curve analysis. The TIMER and TISIDB databases to explore the potential relationship between COL1A1 expression and immune microenvironment in OC tissues. The LinkedOmics and INPUT2 databases were used to analyze differential gene expression in OC, This was followed by enrichment analysis using the Kyoto Encyclopedia of Genes and Genomes (KEGG) and Gene Ontology (GO) annotations to identify and predict potential signaling pathways associated with COL1A1.

Results

Our study demonstrated that COL1A1 expression was significantly elevated in OC tissues compared to normal ovarian tissues. This elevated expression was closely associated with tumor metastasis, poor prognosis, and advanced pathological stages in OC patients. Moreover, COL1A1 expression showed a significant correlation with immune cell infiltration and the expression of immune-related genes within the TME.Further analyses revealed that COL1A1 and its co-expressed genes were primarily enriched in key signaling pathways involved in OC invasion, metastasis, and angiogenesis, indicating its potential role in driving OC progression.

Conclusions

Our study found that upregulation of COL1A1 expression is significantly associated with lymph node metastasis of OC and can affect the immune microenvironment. Based on this, COL1A1 could serve as a promising biomarker for OC prognosis and provide a new perspective for the development of potential immunotherapies for patients with OC.

A new Col1a1 conditional knock-in mouse model to study osteogenesis imperfecta

Osteogenesis imperfecta (OI) constitutes a family of bone fragility disorders characterized by both genetic and clinical heterogeneity. Several different mouse models reproduce the classic features of OI, and the most commonly studied carry either a spontaneous or genetically induced pathogenic variant in the Col1a1 or Col1a2 gene. When OI is caused by primary alterations of type I collagen, it represents a systemic connective tissue disease that, in addition to the skeleton, also affects several extra-skeletal tissues and organs, such as skin, teeth, lung, heart, and others, where the altered type I collagen is also expressed. Currently, existing mouse models harbor a disease-causing genetic variant in all tissues and do not allow assessing the primary vs secondary consequences of the mutation on a specific organ/system. Here, we describe the generation of the first conditional knock-in allele for Col1a1 that can express a severe OI-causing glycine substitution (p.Gly1146Arg) in the triple helical region of α1(I) but only after Cre-driven recombination in the tissue of choice. We called this new dominant allele Col1a1G1146R-Floxed/+ and introduced it into the murine model. We describe its validation by crossing mice carrying this allele with EIIA-Cre expressing mice and showing that offspring with the recombined allele reproduce the classic features of a severe form of OI. The new mouse model will be useful to study the tissue-specific impact of this severe mutation on organs, such as the lung, the heart, and others.

Extra-Skeletal Manifestations in Osteogenesis Imperfecta Mouse Models

Osteogenesis imperfecta (OI) is a rare heritable connective tissue disorder of skeletal fragility with an incidence of roughly 1:15,000. Approximately 85% of the pathogenic variants responsible for OI are in the type I collagen genes, COL1A1 and COL1A2, with the remaining pathogenic OI variants spanning at least 20 additional genetic loci that often involve type I collagen post-translational modification, folding, and intracellular transport as well as matrix incorporation and mineralization. In addition to being the most abundant collagen in the body, type I collagen is an important structural and extracellular matrix signaling molecule in multiple organ systems and tissues. Thus, OI disease-causing variants result not only in skeletal fragility, decreased bone mineral density (BMD), kyphoscoliosis, and short stature, but can also result in hearing loss, dentinogenesis imperfecta, blue gray sclera, cardiopulmonary abnormalities, and muscle weakness. The extensive genetic and clinical heterogeneity in OI has necessitated the generation of multiple mouse models, the growing awareness of non-skeletal organ and tissue involvement, and OI being more broadly recognized as a type I collagenopathy.This has driven the investigation of mutation-specific skeletal and extra-skeletal manifestations and broadened the search of potential mechanistic therapeutic strategies. The purpose of this review is to outline several of the extra-skeletal manifestations that have recently been characterized through the use of genetically and phenotypically heterogeneous mouse models of osteogenesis imperfecta, demonstrating the significant potential impact of OI disease-causing variants as a collagenopathy (affecting multiple organ systems and tissues), and its implications to overall health.

Optimising Health-Related Quality of Life in Children With Osteogenesis Imperfecta

Osteogenesis Imperfecta is a rare, hereditary bone condition with an incidence of 1/15,000-20,000. Symptoms include bone fragility, long bone deformity, scoliosis, hypermobility, alongside secondary features such as short stature, basilar invagination, pulmonary and cardiac complications, hearing loss, dentinogenesis imperfecta and malocclusion. Osteogenesis Imperfecta can have a large impact on the child and their family; this impact starts immediately after diagnosis. Fractures, pain, immobility, hospital admissions and the need for equipment and adaptations all influence the health-related quality of life of the individual and their family. This narrative review article aims to examine the impact the diagnosis and management of osteogenesis imperfecta has on the health-related quality of life of a child. It will touch on the effect this may have on the quality of life of their wider family and friends and identify strategies to optimise health-related quality of life in this population. Optimising health-related quality of life in children with Osteogenesis Imperfecta is often a complicated, multifaceted journey that involves the child, their extended family, school, extracurricular staff and numerous health professionals.

Osteogenesis imperfecta in Peruvian children: Phenotypic and therapeutic insights from a pediatric hospital

Osteogenesis imperfecta (OI) is a genetic disorder of the connective tissue that is characterized by high bone fragility. It has a worldwide incidence of 1 in 10,000. The diagnosis is mainly clinical-radiological. Treatment is based on the use of bisphosphonates and orthopedic surgeries. The objective of this study was to establish the clinical, radiological, and therapeutic characteristics of OI in pediatric patients of a national reference pediatrics institute. This was conducted through a descriptive and retrospective analysis. All patients under 18 years of age with a diagnosis of OI treated at the Instituto Nacional de Salud del Niño de Breña (INSN-Breña) between 2010 and 2021 were included. In total, 91 patients with OI were studied, more than half of whom were male. A total of 93.4% had a history of fractures, 72.5% had blue sclera, 39.6% had bowed legs and 20.9% had dentinogenesis imperfecta. The minimum-maximum value of fractures was 0-18. A total of 75.8% of patients started treatment with bisphosphonates and 41.8% used adjuvant medications. Less than 50% of patients required surgical treatment. Osteogenesis imperfecta is a genetic and chronic pathology. The use of the Van Dijk severity grade and the Aglan severity scale is simple to apply and therefore should be used to improve the classification of groups with the highest risk of fractures and response to treatment. Due to the low incidence of this disease, it is important to raise awareness and increase the research volume on this subject.

Correlation of serum DKK1 level with skeletal phenotype in children with osteogenesis imperfecta

PURPOSE

We aim to detect serum DKK1 level of pediatric patients with OI and to analyze its relationship with the genotype and phenotype of OI patients.

METHODS

A cohort of pediatric OI patients and age-matched healthy children were enrolled. Serum levels of DKK1 and bone turnover biomarkers were measured by enzyme-linked immunosorbent assay. Bone mineral density (BMD) was measured by Dual-energy X-ray absorptiometry. Pathogenic mutations of OI were detected by next-generation sequencing and confirmed by Sanger sequencing.

RESULTS

A total of 62 OI children with mean age of 9.50 (4.86, 12.00) years and 29 healthy children were included in this study. The serum DKK1 concentration in OI children was significantly higher than that in healthy children [5.20 (4.54, 6.32) and 4.08 (3.59, 4.92) ng/mL, P < 0.001]. The serum DKK1 concentration in OI children was negatively correlated with height (r = - 0.282), height Z score (r = - 0.292), ALP concentration (r = - 0.304), lumbar BMD (r = - 0.276), BMD Z score of the lumbar spine and femoral neck (r = - 0.32; r = - 0.27) (all P < 0.05). No significant difference in serum DKK1 concentration was found between OI patients with and without vertebral compression fractures. In patients with spinal deformity (22/62), serum DKK1 concentration was positively correlated with SDI (r = 0.480, P < 0.05). No significant correlation was observed between serum DKK1 concentration and the annual incidence of peripheral fractures, genotype and types of collagen changes in OI children.

CONCLUSION

The serum DKK1 level was not only significantly elevated in OI children, but also closely correlated to their skeletal phenotype, suggesting that DKK1 may become a new biomarker and a potential therapeutic target of OI.

National Trends in Inpatient Hospital Outcomes of Children with Osteogenesis Imperfecta and the Importance of Extraskeletal Manifestations: A Kids' Inpatient Database Study

OBJECTIVE

To investigate the extent of extraskeletal manifestations along with inpatient outcomes and complications associated with osteogenesis imperfecta (OI).

STUDY DESIGN

This cross-sectional study utilized the Kids' Inpatient Database as a part of the Healthcare Cost and Utilization Project to investigate inpatient hospital outcomes and management in patients with OI from 1997 through 2016. Data regarding hospital characteristics, cost of treatment, inpatient outcomes, and procedures were collected and analyzed.

RESULTS

There were 7291 admissions that listed OI as a diagnosis in the Kids' Inpatient Database from 1997 through 2016. Unexpectedly, more than one-third of all admissions in these children with OI presented with an extraskeletal manifestation. The rate of major complications was 3.85%. The rate of minor complications was 19.4%, most commonly respiratory problems. The mortality rate was 18.2% in the neonatal period and 1.0% in all other admissions. Total charges of hospital stay increased over the years.

CONCLUSIONS

We identified a striking prevalence of extraskeletal manifestations in OI along with inpatient outcomes and complications associated with OI, of which respiratory complications were predominant. We observed a significant financial burden for patients with OI and identified additional risks for financial crisis, in addition to disparities in care identified among socioeconomic groups. These data contribute to a more holistic understanding of OI from diagnosis to management.

Changes in serum bone turnover markers and bone mineral density Z-score in children with osteogenesis imperfecta after zoledronic acid treatment

The study aimed to investigate the changes in the levels of serum bone turnover markers (BTMs) and bone mineral density (BMD) Z-score in pediatric patients with osteogenesis imperfecta (OI) after intravenous bisphosphonate therapy and their association with age and estimated glomerular filtration rate (eGFR). This retrospective study analyzed data from 10 pediatric OI patients treated with intravenous zoledronic acid for over 1 year. Patients' clinical data were collected. The levels of BTMs and BMD Z-score before and after zoledronic acid treatment were analyzed. Significant improvement in BMD Z-score was observed after 6 and 12 months of treatment compared to baseline (all p < 0.05). The N-terminal propeptide of type I procollagen (PINP) levels decreased over time (all p < 0.05), indicating that zoledronic acid treatment decreased bone turnover. The levels of beta-C-terminal telopeptide of type I collagen remained stable after treatment. No correlation was found between PINP level and age, eGFR, or BMD (all p > 0.05). Bisphosphonate treatment can improve BMD and decrease bone turnover (indicated by decreased levels of PINP) in pediatric OI patients. PINP may serve as an independent indicator for monitoring the efficacy of bisphosphonate treatment in pediatric OI patients, particularly in those under the age of 6, where standardized BMD Z-score criteria are lacking.

Impact of telescopic intramedullary rodding on the growth of tibia: Comparative experimental study in dogs

INTRODUCTION

The most commonly accepted method of long bone deformity correction in children with osteogenesis imperfecta is surgical realignment with transphyseal telescopic intramedullary rodding. This approach ensures reinforcement of the bone throughout the growth period. Although longitudinal growth does occur with these implants there has been very little work carried out to calculate the effect of such factors as rod position or implant material on growth. We carried out a prospective comparative study on 12 puppies using titanium alloy telescopic tibial rods with and without hydroxyl-apatite coating. The aim of this non-randomized controlled experimental study was to assess the impact of telescopic intramedullary rodding on spontaneous growth of the tibia.

MATERIAL AND METHODS

Twelve mongrel puppies aged of 5 months underwent intramedullary transphyseal rodding of the right tibia. In group I (6 dogs) a titanium telescopic rod was used, in group II (6 dogs) a titanium rod with hydroxyapatite (HA)-coated threaded end was used. The following radiological criteria were assessed before surgery and every month until age of 12 months (natural fusion of physes in dogs): length of tibia, amount of superposition of inner (male) rod into external (female) rod; alteration of anatomy in terms of joint angles (mMPTA, mLDTA, mPPTA, mADTA); positioning of threaded ends in proximal and distal epiphyses and evidence of premature growth arrest. Parameters were compared with left tibia serving as control segment. The null hypothesis was that neither rod position nor implant material altered growth.

RESULTS

The transphyseal rods did not lead to irreversible epiphysiodesis in either group. In group II (HA-coated) some loss of residual length was found in all six dogs, over 7mm (5.9%) in comparison to left intact tibia. In contrast to that, in group I (titanium nail) only one animal (16.7%) demonstrated a tibia length discrepancy of 8mm (4.8%). Eccentric ( posterior) positioning of the rod in the distal epiphysis resulted in a procurvatum deformity (increased anterior distal tibial angle) in both groups. We found no failure of telescoping and no loss of fixation of threaded parts in either epiphyses.

DISCUSSION

The presence of telescopic rods with HA-coated threads parts clearly contributes to inhibition of spontaneous longitudinal growth. We hypothesize that HA stimulates maturation of chondrocytes of growth plate. Our findings regarding the potential adverse effect of thread position in the distal physis demonstrate the importance of attempting to place the rod as central as possible.

CONCLUSION

Titanium alloy telescopic rods did not reveal significant effect on physeal growth in puppies in comparison to HA-coated implants. Transphyseal HA-coated implants did however inhibit growth plate function with mean loss of length of 5.2% compared to the other side. Eccentric positioning of rods relative to center of physis resulted in angular deformity due to irregular growth. There were no cases of mechanical failure or loss of telescopic function with either group of titanium implant.

LEVEL OF EVIDENCE

II; prospective comparative experimental study.

Integrative Management of Bone Deformities in Osteogenesis Imperfecta: A Case Report on Zoledronic Acid and Corrective Osteotomy

Osteogenesis imperfecta (OI) is a hereditary genetic condition characterized by brittle bones that are easily broken. Surgical intervention is necessary frequently to treat fractures and deformities in patients diagnosed with OI. In this case, we discuss a case of a nine-year-old male child diagnosed with OI. This boy was previously operated on one year back for a femur fracture with osteotomy and internal fixation with nails, followed by implant removal at a later stage almost one year later. This boy was brought to our hospital with convex deformities of femur and tibia. Upon evaluation and review of this boy's case, the decision was made to administer a zoledronic acid infusion cycle over three days to enhance bone strength. Following this pharmacological therapy, this patient was planned for corrective osteotomy and internal fixation of the femur. This case underscores the complexities of managing OI and also highlights the importance of the therapeutic role of bisphosphonates like zoledronic acid alongside surgical intervention to address these kinds of bony deformities and improve patient outcomes.

Genetic Background of Medication-Related Osteonecrosis of the Jaw: Current Evidence and Future Perspectives

Medication-related osteonecrosis of the jaw (MRONJ) is a rare side effect of antiresorptive drugs that significantly hinders the quality of life of affected patients. The disease develops in the presence of a combination of factors. Important pathogenetic factors include inflammation, inhibition of bone remodeling, or genetic predisposition. Since the first description of this rare side effect in 2003, a growing body of data has suggested a possible role for genetic factors in the disease. Several genes have been suggested to play an important role in the pathogenesis of MRONJ such as SIRT1, VEGFA, and CYP2C8. With the development of molecular biology, newer methods such as miRNA and gene expression studies have been introduced in MRONJ, in addition to methods that can examine the base sequence of the DNA. Describing the complex genetic background of MRONJ can help further understand its pathophysiology as well as identify new therapeutic targets to better manage this adverse drug reaction.

Respiratory insufficiency in an infant with osteogenesis imperfecta

Osteogenesis imperfecta (OI) is a rare presentation in the pediatric population. Whilst orthopedic manifestations are well-publicised, the multiple respiratory complications and mechanisms of respiratory failure in more severe cases are less well described. We report the clinical, radiological and histopathological details of the case of an infant with genetically-confirmed OI (Type 2) and associated respiratory insufficiency, as well as summarise the relevant existing literature. This case highlights the importance of the recognition of clinical challenges associated with the management of respiratory complications in a patient with OI.

Evaluation of functioning and associated factors in children and adolescents with osteogenesis imperfecta

OBJECTIVE

The aim of this study was to evaluate the functioning and associated factors in children and adolescents with osteogenesis imperfecta (OI).

METHODS

This is a cross-sectional study conducted on 30 children and adolescents with OI. Medical records, use of bisphosphonates, socioeconomic status, handgrip strength, balance, joint hypermobility, ambulatory level, and the Pediatric Evaluation of Disability Inventory-Computer Adaptative Test (PEDI-CAT) scores were assessed. Data is presented as mean and standard deviation and Student's t-test or Mann-Whitney U test. Categorical data is presented as frequency and analyzed using Fisher's exact test. Within-group analyses were conducted using ANCOVA or Wilcoxon signed-rank test. Correlations used Kendall's Tau-b test.

RESULTS

The participants involved in this study were 6-18 years old. The sample was separated into two groups according to disease severity. The moderate/severe OI group (n=10) presented a lower height and muscular strength than the mild group (n=20). Muscle weakness was observed in all participants with OI when compared with the normal population. No differences were observed between the groups in the PEDI-CAT scores except for the mobility domain. There were correlations between the PEDI-CAT mobility domain and the number of fractures, OI type, weight, and balance; there was also a correlation between the PEDI-CAT daily activities, mobility, responsibility, and social/cognitive domains.

CONCLUSIONS

The findings suggest that children with moderate/severe forms of OI can achieve the same function levels as children with mild OI. Fractures can have a major influence on the functional level, and treatment should focus on the prevention and rehabilitation of these events when they occur.

Bone matrix properties in adults with osteogenesis imperfecta are not adversely affected by setrusumab-a sclerostin neutralizing antibody

Osteogenesis imperfecta (OI) is a skeletal dysplasia characterized by low bone mass and frequent fractures. Children with OI are commonly treated with bisphosphonates to reduce fracture rate, but treatment options for adults are limited. In the Phase 2b ASTEROID trial, setrusumab (a sclerostin neutralizing antibody, SclAb) improved bone density and strength in adults with type I, III, and IV OI. Here, we investigate bone matrix material properties in tetracycline-labeled trans iliac biopsies from 3 groups: (1) control: individuals with no metabolic bone disease, (2) OI: individuals with OI, (3) SclAb-OI: individuals with OI after 6 mo of setrusumab treatment (as part of the ASTEROID trial). In addition to bone histomorphometry, bone mineral and matrix properties were evaluated with nanoindentation, Raman spectroscopy, second harmonic generation imaging, quantitative backscatter electron imaging, and small-angle X-ray scattering. Spatial locations of fluorochrome labels were identified to differentiate inter-label bone of the same tissue age and intra-cortical bone. No difference in collagen orientation was found between the groups. The bone mineral density distribution and analysis of Raman spectra indicate that OI groups have greater mean mineralization, greater relative mineral content, and lower crystallinity than the control group, which was not altered by SclAb treatment. Finally, a lower modulus and hardness were measured in the inter-label bone of the OI-SclAb group compared to the OI group. Previous studies suggest that even though bone from OI has a higher mineral content, the extracellular matrix (ECM) has comparable mechanical properties. Therefore, fragility in OI may stem from contributions from other yet unexplored aspects of bone organization at higher length scales. We conclude that SclAb treatment leads to increased bone mass while not adversely affecting bone matrix properties in individuals with OI.

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.

Losartan alters osteoblast differentiation and increases bone mass through inhibition of TGFB signalling in vitro and in an OIM mouse model

Excessive production of Transforming Growth Factor β (TGFβ) is commonly associated with dominant and recessive forms of OI. Previous reports have indicated that administration of TGFβ-targeted antibodies maybe of potential therapeutic benefit to OI patients. However, direct targeting of TGFβ is likely to cause multiple adverse effects including simulation of autoimmunity. In the current study we use patient-derived normal and OI fibroblasts, osteoblasts and OIM mouse models to determine the effects of Losartan, an angiotensin II receptor type 1 (AT1) antagonist, on TGFβ signalling and bone morphology in OI. In OIM mice bred on a mixed background administration of 0.6 g/L losartan for 4 weeks was associated with a significant reduction in TGFβ from 79.2 g/L in the control to 60.0 ng/ml following losartan (p < 0.05), reduced osteoclast activity as measured by CTX from 275.9 ng/ml in the control to 157.2 ng/ml following 0.6 g/L of losartan (p < 0.05) and increased cortical bone thickness (P < 0.001). Furthermore in OIM mice bred on a C57BL/6 background 0.6 g/L losartan increased trabecular bone volume in the tibiae (P < 0.05) and the vertebrae (P < 0.01), increased cortical bone thickness (P < 0.001) reduced the trabecular pattern factor (P < 0.01 and P < 0.001 for the tibiae and vertebrae respectively), reduced osteoclast (P < 0.05) and osteoblast (P < 0.01) numbers as well as reducing the area of bone covered by these cell types. Interestingly, losartan did not affect immune cells infiltrating into bone, nor did this drug alter TGFβ signalling in normal or OI fibroblasts. Instead, losartan reduced SMAD2 phosphorylation in osteoblasts, inhibiting their ability to differentiate. Our data suggest that losartan may be an effective treatment for the bone-associated dysmorphia displayed in OI whilst minimising potential adverse immune cell-related effects.

Lumbar Epidural versus Caudal Epidural for Postoperative Analgesia After Lower Extremity Osteotomy Surgery in Pediatric Patients with Osteogenesis Imperfecta: A Propensity-Matched Cohort Analysis in a Single-Center Over 9 Years

Purpose

Although pediatric epidural analgesia is a well-established technique used perioperatively. It is unclear whether a lumbar or caudal epidural is suitable for osteogenesis imperfecta (OI) patients, which may be associated with brittle bones and spine deformity. We conducted a retrospective study to investigate and compare the efficacy of the two continuous epidural techniques in pediatric patients undergoing lower extremity osteotomy surgery using a propensity score-matched analysis (PSMA).

Patients and Methods

A total of 274 patients were included. Patients' age, weight, and height were adjusted using PSMA. 90 patients were matched for further analysis, with 45 patients in the lumbar epidural group (Group L) and 45 patients in the caudal epidural group (Group C). Pain scores were categorized into three grades: mild (0-3), moderate (4-6), and severe (7-10), and compared between the two groups. Additionally, operation time, operation site, blood loss, scoliosis, oral analgesic medications, and catheter or nerve-related complications were compared.

Results

There were no significant differences in operation time, operation site, scoliosis, and blood loss between the two groups. The percentage of moderate to severe pain during movement was significantly higher in Group L than in Group C, with 37.5% versus 17.5% on the second-day post-operation (P=0.039). However, no statistically significant difference was observed on other days. Additionally, there was no significant difference in oral medication consumption and complications between the two groups.

Conclusion

Both lumbar and caudal epidural analgesia can be effectively used postoperatively, and a caudal epidural should be considered where performing a lumbar epidural is challenging in OI pediatric patients.

The vitamin D status in a Chinese osteogenesis imperfecta population and its correlation with bone metabolic markers and bone density

Objective

Studies on the baseline vitamin D levels in osteogenesis imperfecta (OI) patients before medication are scarce. This study assessed the vitamin D status of a population with OI at both the overall level and within different age groups. It correlated baseline 25-hydroxyvitamin D (25(OH)D) levels with other bone-related factors, biochemical markers, and bone density.

Patients and methods

We collected 25(OH)D levels from 95 OI patients in East China (59 under 18 years old and 36 over 18 years old). Postmenopausal women and men over 50 years old are excluded. Measurements included body indicators, biochemical markers, and bone mineral density (BMD) assessed by Dual-energy X-ray absorptiometry (DXA). Data analysis was performed using SPSS 26.0.

Results

In the overall population, among those under 18 years old, and among those over 18 years old, 87.4, 83.1, and 94.4%, respectively, were vitamin D deficient (<30 ng/mL), while 47.4, 40.7, and 58.3% had vitamin D deficiency (<20 ng/mL), respectively. In the overall population and among those under 18 years old, serum 25(OH)D levels were negatively correlated with age and parathyroid hormone (PTH) levels, and 25(OH)D levels (<10 ng/mL, 10-20 ng/mL, 20-30 ng/mL, >30 ng/mL) showed a negative correlation with BMI. In OI patients under 18 years old, serum 25(OH)D was negatively correlated with serum β-CTX levels. In adult male OI population, 25(OH)D levels were negatively correlated with OI severity (Type I, IV, III). No statistically significant correlation was found between 25(OH)D levels and BMD Z-scores.

Conclusion

This study on OI in East China reveals significant vitamin D insufficiency and deficiency in baseline levels among pediatric, adolescent and adult OI patients. It assesses the correlation of 25(OH)D levels with various influencing factors, providing crucial insights into understanding the impact of OI on vitamin D status across different age groups and aiding in better clinical management of OI patients.

Regulation of bone homeostasis: signaling pathways and therapeutic targets

As a highly dynamic tissue, bone is continuously rebuilt throughout life. Both bone formation by osteoblasts and bone resorption by osteoclasts constitute bone reconstruction homeostasis. The equilibrium of bone homeostasis is governed by many complicated signaling pathways that weave together to form an intricate network. These pathways coordinate the meticulous processes of bone formation and resorption, ensuring the structural integrity and dynamic vitality of the skeletal system. Dysregulation of the bone homeostatic regulatory signaling network contributes to the development and progression of many skeletal diseases. Significantly, imbalanced bone homeostasis further disrupts the signaling network and triggers a cascade reaction that exacerbates disease progression and engenders a deleterious cycle. Here, we summarize the influence of signaling pathways on bone homeostasis, elucidating the interplay and crosstalk among them. Additionally, we review the mechanisms underpinning bone homeostatic imbalances across diverse disease landscapes, highlighting current and prospective therapeutic targets and clinical drugs. We hope that this review will contribute to a holistic understanding of the signaling pathways and molecular mechanisms sustaining bone homeostasis, which are promising to contribute to further research on bone homeostasis and shed light on the development of targeted drugs.

Potential Targeting Mechanisms for Bone-Directed Therapies

Bone development is characterized by complex regulation mechanisms, including signal transduction and transcription factor-related pathways, glycobiological processes, cellular interactions, transportation mechanisms, and, importantly, chemical formation resulting from hydroxyapatite. Any abnormal regulation in the bone development processes causes skeletal system-related problems. To some extent, the avascularity of cartilage and bone makes drug delivery more challenging than that of soft tissues. Recent studies have implemented many novel bone-targeting approaches to overcome drawbacks. However, none of these strategies fully corrects skeletal dysfunction, particularly in growth plate-related ones. Although direct recombinant enzymes (e.g., Vimizim for Morquio, Cerezyme for Gaucher, Elaprase for Hunter, Mepsevii for Sly diseases) or hormone infusions (estrogen for osteoporosis and osteoarthritis), traditional gene delivery (e.g., direct infusion of viral or non-viral vectors with no modifications on capsid, envelope, or nanoparticles), and cell therapy strategies (healthy bone marrow or hematopoietic stem cell transplantation) partially improve bone lesions, novel delivery methods must be addressed regarding target specificity, less immunogenicity, and duration in circulation. In addition to improvements in bone delivery, potential regulation of bone development mechanisms involving receptor-regulated pathways has also been utilized. Targeted drug delivery using organic and inorganic compounds is a promising approach in mostly preclinical settings and future clinical translation. This review comprehensively summarizes the current bone-targeting strategies based on bone structure and remodeling concepts while emphasizing potential approaches for future bone-targeting systems.

Characterization of hearing loss in pediatric patients with osteogenesis imperfecta

INTRODUCTION

Osteogenesis imperfecta (OI) is a common heritable disorder affecting type 1 collagen. The sequelae of OI vary, but hearing loss is a significant complication with 46-58 % of patients having some degree of hearing loss. Previous studies have suggested patients with OI may have conductive, sensorineural, or mixed hearing loss. Majority of these studies focus on the adult population.

OBJECTIVES

Identify a relationship between OI and hearing loss in the pediatric population.

METHODS

The TriNetx Analytics Network, a federated health research network that aggregates the de-identified electronic health record data of over 78 million patients across the United States, was queried for patients 18 years old or younger with a diagnosis of OI. Patients in this group with diagnosis of sensorineural, conductive, or mixed hearing loss were recorded. Patients with diagnoses of congenital cytomegalovirus, congenital inner ear malformations, and noise-induced hearing loss were excluded from analysis.

RESULTS

Out of 3256 patients 18 years old or younger with OI, 10.07 % (95 % CI: 9.06-11.16) had a history of any form of hearing loss, 5.71 % (95 % CI: 4.94-6.57) had conductive hearing loss, 3.01 % (95 % CI: 2.45-3.66) had sensorineural hearing loss, and 1.35 % (95 % CI: 0.98-1.81) had mixed hearing loss. Relative risks for diagnosis of any type of hearing loss, conductive hearing loss, sensorineural hearing loss, and mixed hearing loss were calculated: 5.90 (95 % CI 5.32-6.53), 5.08 (95 % CI 4.42-5.84), 6.18 (95 % CI 5.09-7.51), and 13.86 (95 % CI 10.33-18.59) respectively.

DISCUSSION

This study is the largest to date that describes a relationship between OI and conductive, sensorineural, and mixed hearing loss. Pediatric patients with OI are almost five times as likely to have any type of hearing loss. There was a significant increased risk in each subgroup, but conductive hearing loss was the most common for hearing loss in children with OI. The highest risk subtype when compared to controls was mixed hearing loss.

Effectiveness of whole exome sequencing analyses in the molecular diagnosis of osteogenesis imperfecta

OBJECTIVES

Osteogenesis imperfecta (OI) is a group of phenotypically and genetically heterogeneous connective tissue disorders that share similar skeletal anomalies causing bone fragility and deformation. This study aimed to investigate the molecular genetic etiology and to determine the relationship between genotype and phenotype in OI patients with whole exome sequencing (WES).

METHODS

Multiplex-Ligation dependent Probe Amplification (MLPA) analysis of COL1A1 and COL1A2 and WES were performed on cases between the ages of 0 and 18 whose genetic etiology could not be determined before using a targeted next-generation sequencing panel, including 13 genes (COL1A1, COL1A2, IFITM5, SERPINF1, CRTAP, P3H1, PPIB, SERPINH1, FKBP10, SP7, BMP1, MBTPS2, PLOD2) responsible for OI.

RESULTS

Twelve patients (female/male: 4/8) from 10 different families were included in the study. In 6 (50 %) families, consanguineous marriage was noted. The clinical typing based on Sillence classification; 3 (25 %) patients were considered to be type I, 7 (58.3 %) type III, and 2 (16.7 %) type IV. Deletion/duplication wasn't detected in the COL1A1 and COL1A2 genes in the MLPA analysis of the patients. Twelve patients were molecularly analyzed by WES, and in 6 (50 %) of them, a disease-causing variant in three different genes (FKBP10, P3H1, and WNT1) was identified. Two (33.3 %) detected variants in all genes have not been previously reported in the literature and were considered deleterious based on prediction tools. In 6 cases, no variants were detected in disease-causing genes.

CONCLUSIONS

This study demonstrates rare OI types' clinical and molecular features; genetic etiology was determined in 6 (50 %) 12 patients with the WES analysis. In addition, two variants in OI genes have been identified, contributing to the literature.

Sclerostin inhibition in rare bone diseases: Molecular understanding and therapeutic perspectives

Sclerostin emerges as a novel target for bone anabolic therapy in bone diseases. Osteogenesis imperfecta (OI) and X-linked hypophosphatemia (XLH) are rare bone diseases in which therapeutic potential of sclerostin inhibition cannot be ignored. In OI, genetic/pharmacologic sclerostin inhibition promoted bone formation of mice, but responses varied by genotype and age. Serum sclerostin levels were higher in young OI-I patients, while lower in adult OI-I/III/IV. It's worth investigating whether therapeutic response of OI to sclerostin inhibition could be clinically predicted by genotype and age. In XLH, preclinical/clinical data suggested factors other than identified FGF23 contributing to XLH. Higher levels of circulating sclerostin were detected in XLH. Sclerostin inhibition promoted bone formation in Hyp mice, while restored phosphate homeostasis in age-/gender-dependent manner. The role of sclerostin in regulating phosphate metabolism deserves investigation. Sclerostin/FGF23 levels of XLH patients with/without response to FGF23-antibody warrants study to develop precise sclerostin/FGF23 inhibition strategy or synergistic/additive strategy. Notably, OI patients were associated with cardiovascular abnormalities, so were XLH patients receiving conventional therapy. Targeting sclerostin loop3 promoted bone formation without cardiovascular risks. Further, blockade of sclerostin loop3-LRP4 interaction while preserving sclerostin loop2-ApoER2 interaction could be a potential precise sclerostin inhibition strategy for OI and XLH with cardiovascular safety. The Translational Potential of this Article. Preclinical data on the molecular understanding of sclerostin inhibition in OI and therapeutic efficacy in mouse models of different genotypes, as well as clinical data on serum sclerostin levels in patients with different phenotypes of OI, were reviewed and discussed. Translationally, it would facilitate to develop clinical prediction strategies (e.g. based on genotype and age, not just phenotype) for OI patients responsive to sclerostin inhibition. Both preclinical and clinical data suggested sclerostin as another factor contributing to XLH, in addition to the identified FGF23. The molecular understanding and therapeutic effects of sclerostin inhibition on both promoting bone anabolism and improving phosphate homostasis in Hyp mice were reviewed and discussed. Translationaly, it would facilitate the development of precise sclerostin/FGF23 inhibition strategy or synergistic/additive strategy for the treatment of XLH. Cardiovascular risk could not be ruled out during sclerostin inhibition treatment, especially for OI and XLH patients with cardiovascular diseases history and cardiovascular abnormalities. Studies on the role of sclerostin in inhiting bone formation and protecting cardiovascular system were reviewed and discussed. Translationaly, blockade of sclerostin loop3-LRP4 interaction while preserving sclerostin loop2-ApoER2 interaction could be a potential precise sclerostin inhibition strategy for OI and XLH with cardiovascular safety.

Metabolic Bone Diseases Affecting Tooth Eruption: A Narrative Review

Tooth eruption is an essential process for the development of the oral and maxillofacial system. Several inherited and acquired diseases might affect this tightly regulated process, resulting in premature, delayed, or even failed tooth eruption. The purpose of this article is to review the literature and the clinical parameters of metabolic bone diseases that affect tooth eruption. It examines the physiological aspects of tooth eruption and the pathophysiological changes induced by metabolic bone diseases, including changes in bone metabolism, density, and structure. The search strategy for this review included an electronic search in PubMed, Google Scholar, Medline, Scopus, and the Cochrane Library using the following keywords: "metabolic bone diseases", "tooth eruption", "delayed tooth eruption", and each reported disease in combination with "tooth eruption disorders", covering publications up to March 2024 and limited to English-language sources. Understanding the influence of metabolic bone diseases on tooth eruption is crucial for managing both dental and skeletal manifestations associated with these disorders. This review suggests that a multidisciplinary approach to treatment may significantly improve oral outcomes for patients suffering from such conditions. Clinicians should be aware of the specific dental abnormalities that may arise and consider comprehensive evaluations and individualized treatment plans. These findings underscore the need for further research into targeted therapies that address these abnormalities.

Current situation of osteogenesis imperfecta in Spain: results from a Delphi study

BACKGROUND

Osteogenesis imperfecta (OI) is a rare disease characterized by low bone mass and bone fragility, associated with an increased risk of fractures, and skeletal and extra-skeletal symptoms that results in an impairment of health-related quality of life of OI patients. Since published studies on OI in Spain are limited, this study aimed to determine the epidemiology, assessed the disease burden, management and unmet needs of OI patients in Spain. Thirty-four experts in the management of patients with osteogenesis imperfecta completed two rounds of online consultation and reported real-life experience and data from Spanish hospitals. Delphi study questionnaires were based on literature review. A working group of nationally recognized clinical experts supported the development of the study questionnaires and the final validation of results.

RESULTS

The estimated prevalence of patients diagnosed with OI in Spain is 0.56:10,000 inhabitants (95%CI: 0.54-0.59), which represents that, approximately, 2,669 OI patients are currently managed in Spanish hospitals. It is estimated that approximately 269 new patients would be diagnosed with OI each year in Spain, representing an estimated incidence of 0.06 (95%CI: 0.05-0.06) per 10,000 inhabitants per year. Clinical management of OI in Spain is performed by a range of medical specialists; however, multidisciplinary care is not fully implemented. The absence of an approved curative treatment or a treatment to reduce the clinical features of the disease remains the main unmet need.

CONCLUSIONS

This study provides a snapshot of the current situation of patients with OI in Spain reported by clinical experts. The results provide an estimation of the epidemiology of the disease, and complement the available evidence on disease burden, clinical management, and unmet needs of these patients in Spain.

Safety and Efficacy of Denosumab in Children With Osteogenesis Imperfecta-the First Prospective Comparative Study

CONTEXT

Denosumab is a potential therapeutic agent for osteogenesis imperfecta (OI), but its efficacy and safety remain unclear in children with OI.

OBJECTIVE

We aimed to investigate the effects of denosumab on bone mineral density (BMD), spinal morphometry, and safety in children with OI compared with zoledronic acid.

METHODS

In this prospective study, 84 children or adolescents with OI were randomized to receive denosumab subcutaneous injection every 6 months or zoledronic acid intravenous infusion once. Changes of BMD and its Z-score, vertebral shape, serum levels of calcium and bone turnover biomarkers were assessed during the 1-year treatment.

RESULTS

After 12 months of treatment, BMD at the lumbar spine, femoral neck, and total hip significantly increased by 29.3%, 27.8%, and 30.2% in the denosumab group, and by 32.2%, 47.1%, and 41.1% in the zoledronic acid group (all P < .001 vs baseline). Vertebral height and projection area significantly increased after denosumab and zoledronic acid treatment. Rebound hypercalcemia was found to be a common and serious side effect of denosumab, of which 14.3% reached hypercalcemic crisis. Rebound hypercalcemia could be alleviated by switching to zoledronic acid treatment.

CONCLUSION

Treatment with denosumab or zoledronic acid is beneficial in increasing BMD and improving the spinal morphometry of children with OI. However, denosumab should be used with caution in pediatric patients with OI because of its common and dangerous side effect of rebound hypercalcemia. The appropriate dosage and dosing interval of denosumab need to be further explored in children with OI.

The IFITM5 mutation in osteogenesis imperfecta type V is associated with an ERK/SOX9-dependent osteoprogenitor differentiation defect

Osteogenesis imperfecta (OI) type V is the second most common form of OI, distinguished by hyperplastic callus formation and calcification of the interosseous membranes, in addition to the bone fragility. It is caused by a recurrent, dominant pathogenic variant (c.-14C>T) in interferon-induced transmembrane protein 5 (IFITM5). Here, we generated a conditional Rosa26-knockin mouse model to study the mechanistic consequences of the recurrent mutation. Expression of the mutant Ifitm5 in osteo-chondroprogenitor or chondrogenic cells resulted in low bone mass and growth retardation. Mutant limbs showed impaired endochondral ossification, cartilage overgrowth, and abnormal growth plate architecture. The cartilage phenotype correlates with the pathology reported in patients with OI type V. Surprisingly, expression of mutant Ifitm5 in mature osteoblasts caused no obvious skeletal abnormalities. In contrast, earlier expression in osteo-chondroprogenitors was associated with an increase in the skeletal progenitor cell population within the periosteum. Lineage tracing showed that chondrogenic cells expressing the mutant Ifitm5 had decreased differentiation into osteoblastic cells in diaphyseal bone. Moreover, mutant IFITM5 disrupted early skeletal homeostasis in part by activating ERK signaling and downstream SOX9 protein, and inhibition of these pathways partially rescued the phenotype in mutant animals. These data identify the contribution of a signaling defect altering osteo-chondroprogenitor differentiation as a driver in the pathogenesis of OI type V.

The Versatility of Collagen in Pharmacology: Targeting Collagen, Targeting with Collagen

Collagen, a versatile family of proteins with 28 members and 44 genes, is pivotal in maintaining tissue integrity and function. It plays a crucial role in physiological processes like wound healing, hemostasis, and pathological conditions such as fibrosis and cancer. Collagen is a target in these processes. Direct methods for collagen modulation include enzymatic breakdown and molecular binding approaches. For instance, Clostridium histolyticum collagenase is effective in treating localized fibrosis. Polypeptides like collagen-binding domains offer promising avenues for tumor-specific immunotherapy and drug delivery. Indirect targeting of collagen involves regulating cellular processes essential for its synthesis and maturation, such as translation regulation and microRNA activity. Enzymes involved in collagen modification, such as prolyl-hydroxylases or lysyl-oxidases, are also indirect therapeutic targets. From another perspective, collagen is also a natural source of drugs. Enzymatic degradation of collagen generates bioactive fragments known as matrikines and matricryptins, which exhibit diverse pharmacological activities. Overall, collagen-derived peptides present significant therapeutic potential beyond tissue repair, offering various strategies for treating fibrosis, cancer, and genetic disorders. Continued research into specific collagen targeting and the application of collagen and its derivatives may lead to the development of novel treatments for a range of pathological conditions.

Genetic Evaluation for Monogenic Disorders of Low Bone Mass and Increased Bone Fragility: What Clinicians Need to Know

PURPOSE OF REVIEW

The purpose of this review is to outline the principles of clinical genetic testing and to provide practical guidance to clinicians in navigating genetic testing for patients with suspected monogenic forms of osteoporosis.

RECENT FINDINGS

Heritability assessments and genome-wide association studies have clearly shown the significant contributions of genetic variations to the pathogenesis of osteoporosis. Currently, over 50 monogenic disorders that present primarily with low bone mass and increased risk of fractures have been described. The widespread availability of clinical genetic testing offers a valuable opportunity to correctly diagnose individuals with monogenic forms of osteoporosis, thus instituting appropriate surveillance and treatment. Clinical genetic testing may identify the appropriate diagnosis in a subset of patients with low bone mass, multiple or unusual fractures, and severe or early-onset osteoporosis, and thus clinicians should be aware of how to incorporate such testing into their clinical practices.

Dental Profile of Brazilian Patients with Rare Skeletal Genetic Disorders: Clinical Features and Associated Factors

The aim of this study is to compare the dental profiles of Brazilian patients with rare genetic skeletal disorders and normotypical patients. A cross-sectional study was carried out with 210 individuals aged between 2 and 54 years old [105 with rare diseases (Mucopolysaccharidosis/MPS n = 27 and Osteogenesis Imperfecta/OI n = 78) and 105 without rare diseases] and their parents/caregivers. The parents/caregivers answered a questionnaire about individual aspects of their child and the dental profile was identified from questions related to dental history and the presence/absence of dental problems. The patients' oral cavity was also examined by three examiners for dental caries, malocclusion, gingivitis, and dental anomalies. The average age of individuals with a rare disease was 14.1 years (±12.2) and the median was 9.5 years. Participants who had already used the public health system (SUS) dental care services had a 2.24 times higher chance of belonging to the group with a rare disease (OR = 2.24; 95% CI: 1.07-4.89). Patients with rare diseases are 14.86 times more likely to have difficulty receiving dental treatment (OR = 14.86; 95% CI: 5.96-27.03) and 10.38 times more likely to have one or more dental problems (OR = 10.38; 95% CI: 1.95-35.17). Individuals with rare disorders have a greater history of difficulty in accessing dental treatment, using the SUS, and were diagnosed with more dental problems compared to normotypical individuals.

Osteogenesis Imperfecta Type II: The Lethal Newborn Form Diagnosed in the Postnatal Period

Osteogenesis imperfecta (OI) is a rare inherited skeletal disease, characterized by bone fragility and low bone density. There are several types of OI, varying in severity from benign to severe. We report a case of type II OI, which is a lethal form according to the Sillence classification. At birth, the newborn presented immediate respiratory distress. Postnatal examination and bone radiography confirmed the diagnosis of OI type IIA. The genetic analysis was done along with genetic counseling. Death occurred on day nine of life due to respiratory failure secondary to pulmonary hypoplasia.

Influence of zoledronic acid and pamidronate on tooth eruption in children with osteogenesis imperfecta

INTRODUCTION

Osteogenesis imperfecta (OI) is a congenital disease comprising a heterogeneous group of inherited connective tissue disorders. The main treatment in children is bisphosphonate therapy. Previous animal studies have shown that bisphosphonates delay tooth eruption. The aim of this study is to determine whether patients with OI treated with pamidronate and/or zoledronic acid have a delayed eruption age compared to a control group of healthy children.

METHODS

An ambispective longitudinal cohort study evaluating the age of eruption of the first stage mixed dentition in a group of children with OI (n = 37) all treated with intravenous bisphosphonates compared with a group of healthy children (n = 89). Within the study group, the correlation (Pearson correlation test) between the type of medication administered (pamidronate and/or zoledronic acid) and the chronology of tooth eruption is established, as well as the relationship between the amount of cumulative dose received and tooth eruption.

RESULTS

The age of eruption of the study group was significantly delayed compared to the age of eruption of the control group for molars and lateral incisors (p < 0.05). Patients who received higher cumulative doses had a delayed eruption age compared to those with lower cumulative doses (p < 0.05). There is a high positive correlation between age of delayed tooth eruption and Zoledronic acid administration.

CONCLUSION

Patients with OI have a delayed eruption of the 1st stage mixed dentition compared to a control group of healthy children. This delayed eruption is directly related to the cumulative dose of bisphosphonates and the administration of zoledronic ac.

Exome Sequencing for the Diagnostics of Osteogenesis Imperfecta in Six Russian Patients

Osteogenesis imperfecta (OI) is a group of inherited disorders of connective tissue that cause significant deformities and fragility in bones. Most cases of OI are associated with pathogenic variants in collagen type I genes and are characterized by pronounced polymorphisms in clinical manifestations and the absence of clear phenotype-genotype correlation. The objective of this study was to conduct a comprehensive molecular-genetic and clinical analysis to verify the diagnosis of OI in six Russian patients with genetic variants in the COL1A1 and COL1A2 genes. Clinical and laboratory data were obtained from six OI patients who were observed at the Medical Genetics Center in Saint Petersburg from 2016 to 2023. Next-generation sequencing on MGISEQ G400 (MGI, China) was used for DNA analysis. The GATK bioinformatic software (version 4.5.0.0) was used for variant calling and hard filtering. Genetic variants were verified by the direct automatic sequencing of PCR products using the ABI 3500X sequencer. We identified six genetic variants, as follows pathogenic c.3505G>A (p. Gly1169Ser), c.769G>A (p.Gly257Arg), VUS c.4123G>A (p.Ala1375Thr), and c.4114A>T (p.Asn1372Tyr) in COL1A1; and likely pathogenic c.2035G>A (p.Gly679Ser) and c.739-2A>T in COL1A2. In addition, clinical cases are presented due to the presence of the c.4114A>T variant in the COL1A2 gene. Molecular genetics is essential for determining different OI types due to the high similarity across various types of the disease and the failure of unambiguous diagnosis based on clinical manifestations alone. Considering the variable approaches to OI classification, an integrated strategy is required for optimal patient management.

Impaired muscle parameters in adults with mild to severe types of osteogenesis imperfecta: a cross-sectional study

Impaired muscle parameters may further compromise the already compromised skeleton in individuals with OI. This cross-sectional study aimed to compare muscle function and body composition in adults with various OI types and healthy controls. Sixty-eight adults with OI (mean age 42.2 yr; 27 men) and 68 healthy age- and sex-matched controls were recruited. Maximal isometric muscle force was assessed by handheld dynamometry (hand grip, hip flexors, shoulder abductors, and ankle dorsiflexors), muscle endurance by posture maintenance tests (shoulder abduction, hip flexion, and wall sit), and functional lower limb strength by 30-s chair rise test. In a sub cohort, dynamic muscle function (peak power and force) was assessed by a ground reaction force plate, and lean and fat mass, muscle and fat cross-sectional area (CSA), and muscle density by dual-energy X-ray absorptiometry and peripheral quantitative computed tomography. Multiple linear regression models were fitted with group (OI type I, III, IV/V, or controls), country, sex, and age in the fixed effects part. Overall, adults with various types of OI had lower isometric, endurance, and functional muscle strength (mean difference [MD] = OI type I: 19-43%, OI type IV/V: 25-68%, OI type III: 20-72%) compared to controls. Furthermore, adults with OI type I had lower dynamic muscle function (peak force [MD = 25-29%] and power [MD = 18-60%]), lean mass (MD = 10-17%), muscle CSA (MD = 9-21%), and muscle density (MD = 2-3%) but higher adiposity indices (MD = 24-42%) compared to controls. Functional lower limb strength and maximal muscle force were significantly different between OI types, whereas muscle endurance was not. To conclude, adults with OI present with markedly impaired muscle function which may partially be explained by their altered body composition. Our findings emphasize the need for proper assessment of various muscle parameters and (research into) appropriate and safe muscle strengthening approaches in this population.

Home care needs assessment among caregivers of children and adolescents with osteogenesis imperfecta: a cross-sectional study

BACKGROUND

Children and adolescents with complex medical issues need home care services; however, few studies have provided insight into the unmet home care needs of the families of patients with osteogenesis imperfecta (OI). In this study, we aimed to assess the home care needs of caregivers of children and adolescents with OI and the associated factors.

METHODS

A self-administered questionnaire was administered online to 142 caregivers of patients with OI aged 3-17 years between May and October 2022 from 25 provinces in China. The questionnaire comprised 15 questions on demographic variables and 14 questions on home care needs. Chi-square analysis was used to compare group differences for categorical variables. Multivariate binary logistic regression analysis was conducted to examine predictors of caregivers' home care needs.

RESULTS

The study findings indicated that 81.5% of caregivers had high home care needs. The three leading types of home care needs were helping the child carry out physical fitness recovery exercises at home (72.5%), understanding precautions regarding treatment drugs (72.5%), and relieving the child's pain (70.4%). OI patients' poor self-care ability (adjusted odds ratio = 5.9, 95% confidence interval = 1.8-19.0) was related to caregivers' high level of home care needs.

CONCLUSIONS

The findings of this study suggest that future scientific research and nursing guidance should focus on OI patients' physical training, medication management, pain relief, fracture prevention, and treatment. In addition, caregivers of patients with poor self-care ability should receive special attention in the development of interventions. This study can help with addressing the unmet home care needs of caregivers of children and adolescents with OI. It is vital to develop a personalized intervention plan based on patients' self-care ability.