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Bernard J Smilde,1– 3 Esmée Botman,1– 3 Ruben D de Ruiter,1– 3 Jan Maerten Smit,2,4 Berend P Teunissen,2,5 Wouter D Lubbers,2,6 Lothar A Schwarte,2,6 Patrick Schober,2,6 E Marelise W Eekhoff1– 3 1Amsterdam UMC Location Vrije Universiteit Amsterdam, Department of Internal Medicine Section Endocrinology, Amsterdam, the Netherlands; 2Amsterdam UMC, Amsterdam Bone Center, Amsterdam, the Netherlands; 3Amsterdam Movement Sciences, Tissue Function and Regeneration, Amsterdam, the Netherlands; 4Amsterdam UMC Location Vrije Universiteit Amsterdam, Department of Plastic, Reconstructive and Hand Surgery, Amsterdam, the Netherlands; 5Amsterdam UMC location Vrije Universiteit Amsterdam, Department of Radiology and Nuclear Medicine, Amsterdam, the Netherlands; 6Amsterdam UMC Location Vrije Universiteit Amsterdam, Department of Anaesthesiology, Amsterdam, the NetherlandsCorrespondence: E Marelise W Eekhoff, Department of Internal Medicine section Endocrinology, Amsterdam UMC location Vrije Universiteit Amsterdam, De Boelelaan 1117, Amsterdam, the Netherlands, Tel +31 204440588, Email emw.eekhoff@amsterdamumc.nlAbstract: Fibrodysplasia ossificans progressiva (FOP), sometimes known as myositis ossificans progressiva, is an ultra-rare disease in which bone is formed in muscular tissue, tendons and ligaments. This is known as heterotopic ossification (HO). FOP is caused by a heterozygous mutation in the highly conserved ACVR1/ALK2 gene which affects about 1 in 1.5– 2 million individuals. At birth, patients with the predominant R206H mutation only exhibit a bilateral hallux valgus. During childhood, heterotopic bone formation develops in a typical pattern, affecting the axial muscles first before appendicular body parts are involved. HO can start spontaneously but is often elicited by soft tissue trauma or medical procedures. After soft tissue injury, an inflammatory process called a flare-up can start, followed by the formation of HO. HO leads to a limited range of motion, culminating in complete ankylosis of nearly all joints. As a result of HO surrounding the thorax, patients often suffer from thoracic insufficiency syndrome (TIS). TIS is the most common cause of a limited life expectancy for FOP patients, with a median life expectancy of 56 years. Management is focused on preventing soft-tissue injury that can provoke flare-ups. This includes prevention of iatrogenic damage by biopsies, intramuscular injections and surgery. Anti-inflammatory medication is often started when a flare-up occurs but has a poor basis of evidence. Several forms of potential treatment for FOP are being researched in clinical trials. Progression of the disease is monitored using CT and 18F-NaF PET/CT combined with functional assessments. Patients are regularly evaluated for frequently occurring complications such as restrictive lung disease. Here, we review the current management, monitoring and treatment of FOP.Keywords: fibrodysplasia ossificans progressiva, heterotopic ossification, activin A receptor type 1, treatment strategies

Osteogenesis Imperfecta (OI), known as "brittle bone disease," presents a rare genetic disorder characterized by bone fragility, often accompanied by skeletal deformities and extraskeletal complications. OI is primarily associated with collagen type I defects, responsible for the syndromic nature of the disease affecting a broad range of tissues. As such, its multisystemic complexity necessitates multidisciplinary care approaches in all patient life stages. OI treatment remains largely supportive, commonly including bisphosphonates and orthopedic surgeries, which show promise in children. Although rehabilitation programs for children exist, guidelines for adult care and especially the transition from pediatric to adult care, are lagging behind in OI care and research. The current systematic review summarizes the literature on OI patient pediatric to adult care transition experiences and compares OI transition approaches to other chronic diseases. The review was performed based on the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Systematic searches were conducted across multiple databases. Search terms encompassed synonyms and closely related phrases relevant to "OI" and "Transition to adult care". The initial screening involved the evaluation of article titles, followed by a thorough review of abstracts to assess relevance for the purpose of the current review. Programs aimed at easing the transition from pediatric to adult OI care necessitate a multifaceted approach. Collaborative efforts between different medical disciplines including pediatricians, endocrinologists, orthopedics, cardiology, pulmonology, ophthalmology, otolaryngologists, maxillofacial specialists, psychologists and medical genetics, are crucial for addressing the diverse needs of OI patients during this critical life phase. Comprehensive education, readiness assessments, personalized transition plans, and further follow-up are essential components of a structured transition framework. Further research is warranted to evaluate the feasibility and efficacy of sequential stepwise transition systems tailored to individuals with OI., Competing Interests: Declarations Conflict of interest Luca, Mark R. Garrelfs, Ralph J. B. Sakkers, Mariet W. Elting, Mauro Celli, Arend Bökenkamp, Cas Smits, Thadé Goderie, Jan Maerten Smit, Lothar A. Schwarte, Patrick R. Schober, Wouter D. Lubbers, Marieke C. Visser, Arthur J. Kievit, Barend J. van Royen, Marjolijn Gilijamse, Willem H. Schreuder, Thomas Rustemeyer, Angela Pramana, Jan-Jaap Hendrickx, Max R. Dahele, Peerooz Saeed, Annette C. Moll, Katie R. Curro–Tafili, Ebba A. E. Ghyczy, Chris Dickhoff, Robert A. de Leeuw, Jaap H. Bonjer, Jakko A. Nieuwenhuijzen, Thelma C. Konings, Anton F. Engelsman, Augustinus M. Eeckhout, Joost G. van den Aardweg, Patrick J. Thoral, David P. Noske, Leander Dubois, Berend P. Teunissen, Oliver Semler, Lena Lande Wekre, Katre Maasalu, Aare Märtson, Luca Sangiorgi, Paolo Versacci, Mara Riminucci, Paola Grammatico, Anna Zambrano, Lorena Martini, Marco Castori, Esmee Botman, Ingunn Westerheim, Lidiia Zhytnik, Dimitra Micha, Elisabeth Marelise W. Eekhoff have no competing interests to declare that are relevant to the content of this article. Ethical Approval Not applicable., (© 2024. The Author(s).)

Osteogenesis imperfecta (OI) is a rare genetic disorder characterized by fragile bones and skeletal deformities. Individuals with OI may have dental abnormalities such as dentinogenesis imperfecta (DI) type I, malocclusions, and unerupted or missing teeth. This review comprehensively examines these dental abnormalities to assess their prevalence among the OI population and explore potential differences across different clinical types of OI and pathogenic variants. In accordance with the PRISMA guidelines, a systematic literature search in PubMed, Embase, and Web of Science was conducted that included articles up to June 2024. Out of 672 articles screened, 34 were included. The included studies confirmed that dental abnormalities are prevalent in OI, with DI prevalence ranging from approximately 20 to 48%. Those with a more severe skeletal phenotype (OI type III/IV) exhibited more dental abnormalities than those with a milder skeletal phenotype (OI type I). Notably, OI type V individuals generally do not have DI, although a few isolated cases have been reported. The prevalence of occlusion types varied: Class I occlusion ranged from 14.8 to 50% and Class II malocclusion ranged from 0 to 37.5%, while Class III malocclusion from 4.1 to 84%. This differs from the general population, where Class III malocclusion is typically the least common. Open bites, cross-bites, and unerupted and missing teeth are also commonly reported, particularly in OI types III and IV. This review emphasizes the need for comprehensive dental examinations in OI due to the high prevalence of dental abnormalities. Additionally, the review draws attention to the lack of clear guidelines for diagnosing DI., (© 2024. The Author(s).)

Aims: Various dietary risk factors for type 2 diabetes have been identified. A short assessment of dietary patterns related to the risk for type 2 diabetes mellitus may be relevant in clinical practice given the largely preventable nature of the disease. The aim of this study was to investigate the reproducibility of a short food frequency questionnaire based on available knowledge of diabetes-related healthy diets. In addition, we aimed to investigate whether a Diabetes Dietary Quality Index based on this questionnaire was related to metabolic risk factors, including measures of beta cell function and insulin sensitivity., Methods: A short food frequency questionnaire was composed by selecting fourteen questions (representing eight dietary factors) from existing food frequency questionnaires on the basis of their reported relationship with diabetes risk. Healthy participants (N = 176) from a Dutch family study completed the questionnaire and a subgroup (N = 123) completed the questionnaire twice. Reproducible items from the short questionnaire were combined into an index. The association between the Diabetes Dietary Quality index and metabolic risk factors was investigated using multiple linear regression analysis. Measures of beta cell function and insulin sensitivity were derived from a mixed meal test and an euglycemic-hyperinsulinemic and modified hyperglycemic clamp test., Results: Our results show that this new short food frequency questionnaire is reliable (Intraclass Correlations ranged between 0.5 and 0.9). A higher Diabetes Dietary Quality index score was associated with lower 2 h post-meal glucose (β -0.02, SE 0.006, p < 0.05), HbA1c (β -0.07, SE 0.02, p < 0.05), total cholesterol, (β -0.02, SE 0.07, p < 0.05), LDL cholesterol, (β -0.19, SE 0.07, p < 0.05), fasting (β -0.4, SE 0.16, p < 0.05) and post-load insulin, (β -3.9, SE 1.40, p < 0.05) concentrations and the incremental AUC of glucose during MMT (β -1.9, SE 0.97, p < 0.05). The scores obtained for the oral glucose insulin sensitivity-derived mixed meal test were higher in subjects who scored higher on the Diabetes Dietary Quality index (β 0.89, 0.39, p < 0.05). In contrast, we found no significant associations between the Diabetes Dietary Quality index and clamp measures of beta cell function., Conclusions: We identified a questionnaire-derived Diabetes Dietary Quality index that was reproducible and inversely associated with a number of type 2 diabetes mellitus and metabolic risk factors, like 2 h post-meal glucose, Hba1c and LDL, and total cholesterol. Once relative validity has been established, the Diabetes Dietary Quality index could be used by health care professionals to identify individuals with diets adversely related to development of type 2 diabetes.

Fibrodysplasia ossificans progressiva (FOP) is a rare genetic bone disorder characterized by episodic flare-ups in connective tissue, which are frequently followed by the formation of heterotopic ossification. The absence of available plasma-soluble biomarkers for flare-ups or heterotopic bone formation poses severe challenges to the monitoring of disease activity to measure or predict disease progression. Recently, 18-fluor-sodium fluoride positron emission tomography/computed tomography ([ 18 F]NaF PET/CT) was introduced as a potential marker for ossifying FOP activity. This review discusses the pharmacokinetics of [ 18 F]NaF in relation to the pathophysiology of FOP, and its use as a marker of local bone metabolism in a variety of bone-related disorders. In addition, the review specifically addresses the applicability of [ 18 F]NaF PET/CT imaging in FOP as a monitoring modality.

Osteogenesis imperfecta (OI), a rare genetic connective tissue disorder, primarily arises from pathogenic variants affecting the production or structure of collagen type I. In addition to skeletal fragility, individuals with OI may face an increased risk of developing ophthalmic diseases. This association is believed to stem from the widespread presence of collagen type I throughout various parts of the eye. However, the precise consequences of abnormal collagen type I on different ocular tissues remain unknown. Of particular significance is the sclera, where collagen type I is abundant and crucial for maintaining the structural integrity of the eye. Recent research on healthy individuals has uncovered a unique organizational pattern of collagen fibers within the sclera, characterized by fiber arrangement in both circular and radial layers around the optic nerve head. While the precise function of this organizational pattern remains unclear, it is hypothesized to play a role in providing mechanical support to the optic nerve. The objective of this study is to investigate the impact of abnormal collagen type I on the sclera by assessing the fiber organization near the optic nerve head in individuals with OI and comparing them to healthy individuals. Collagen fiber orientation of the sclera was measured using polarization-sensitive optical coherence tomography (PS-OCT), an extension of the conventional OCT that is sensitive to materials that exhibit birefringence (axial changes in light refraction). Birefringence was quantified and used as imaging contrast to extract collagen fiber orientation as well as the thickness of the radially oriented scleral layer. Three individuals with OI, exhibiting different degrees of disease severity, were assessed and analyzed, along with seventeen healthy individuals. Mean values obtained from individuals with OI were descriptively compared to those of the healthy participant group. PS-OCT revealed a similar orientation pattern of scleral collagen fibers around the optic nerve head between OI individuals and healthy individuals. However, two OI participants exhibited reduced mean birefringence of the radially oriented scleral layer compared to the healthy participant group (OI participant 1 oculus dexter et sinister (ODS): 0.34°/μm, OI participant 2: ODS 0.26°/μm, OI participant 3: OD: 0.29°/μm, OS: 0.28°/μm, healthy participants: ODS 0.38 ± 0.05°/μm). The radially oriented scleral layer was thinner in all OI participants although within ±2 standard deviations of the mean observed in healthy individuals (OI participant 1 OD: 101 μm, OS 104 μm, OI participant 2: OD 97 μm, OS 98 μm, OI participant 3: OD: 94 μm, OS 120 μm, healthy participants: OD 122.8 ± 13.6 μm, OS 120.8 ± 15.1 μm). These findings imply abnormalities in collagen organization or composition, underscoring the necessity for additional research to comprehend the ocular phenotype in OI., (Copyright © 2024 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Fibrodysplasia ossificans progressiva (FOP) is an ultra-rare disorder, characterized by progressive heterotopic ossification (HO) and painful soft-tissue inflammatory flare-ups. This was a post hoc analysis from a phase 2 (NCT03188666) trial in which adults with FOP received intravenous anti-activin A antibody garetosmab 10 mg/kg or placebo every 4 wk over 28 wk (Period 1), followed by a 28-wk open-label treatment and extension (Periods 2 and 3). Here we describe flare-ups, their relationship to new HO lesions, and the impact of garetosmab on flare-ups. Volume of new HO lesions was measured by CT. Patient-reported flare-ups were defined by any 2 of the following: new onset of pain, swelling, joint stiffness, decrease in movement, or perceived presence of HO. Flare-ups were experienced by 71% (17/24) of placebo-treated patients, 59% (10/17) of whom developed a new HO lesion irrespective of flare-up location; 24% of flare-ups location-matched new HO lesions. Twenty-nine new HO lesions occurred in the placebo cohort by week 28, of which 12 (41%) occurred in the same location as new or ongoing flare-ups. A higher volume of newly formed heterotopic bone (week 28) occurred in placebo-treated patients who had experienced a prior flare-up vs those without (median [Q1:Q3] of 16.6 [12.0:31.1] vs 3.2 cm3). Garetosmab was previously shown to decrease patient-reported flare-up frequency in Period 1; here, garetosmab reduced the median (Q1:Q3) duration of patient-reported flares (15.0 [6.0:82.0] vs 48.0 [15.0:1.00] d) and the severity of flare-ups vs placebo. Frequency of corticosteroid use was numerically reduced in those treated with garetosmab (40.0%) vs placebo (58.3%). In this analysis, 71% of placebo-treated adults with FOP experienced flare-ups over 28 wk, which were associated with an increased volume of newly formed heterotopic bone. Garetosmab reduced the severity and duration of flare-ups, with effects sustained during the entire trial., (© The Author(s) 2024. Published by Oxford University Press on behalf of the American Society for Bone and Mineral Research.)

Plastin-3 (PLS3) encodes T-plastin, an actin-bundling protein mediating the formation of actin filaments by which numerous cellular processes are regulated. Loss-of-function genetic defects in PLS3 are reported to cause X-linked osteoporosis and childhood-onset fractures. However, the molecular etiology of PLS3 remains elusive. Functional compensation by actin-bundling proteins ACTN1, ACTN4, and FSCN1 was investigated in zebrafish following morpholino-mediated pls3 knockdown. Primary dermal fibroblasts from six patients with a PLS3 variant were also used to examine expression of these proteins during osteogenic differentiation. In addition, Pls3 knockdown in the murine MLO-Y4 cell line was employed to provide insights in global gene expression. Our results showed that ACTN1 and ACTN4 can rescue the skeletal deformities in zebrafish after pls3 knockdown, but this was inadequate for FSCN1. Patients' fibroblasts showed the same osteogenic transdifferentiation ability as healthy donors. RNA-seq results showed differential expression in Wnt1 , Nos1ap , and Myh3 after Pls3 knockdown in MLO-Y4 cells, which were also associated with the Wnt and Th17 cell differentiation pathways. Moreover, WNT2 was significantly increased in patient osteoblast-like cells compared to healthy donors. Altogether, our findings in different bone cell types indicate that the mechanism of PLS3-related pathology extends beyond actin-bundling proteins, implicating broader pathways of bone metabolism.

Eagle syndrome is a bone disease where elongation of the styloid process leads to throat and neck pain, and in severe cases neurovascular symptoms such as syncope and neuralgia. The pathophysiology of Eagle syndrome is poorly understood with various theories having been proposed how this elongation is caused. To better understand the pathophysiology, we performed a work-up in 6 patients presenting with Eagle syndrome. Patients mainly presented with pain on turning the neck (100%), foreign body sensation (67%), tension in the neck (67%), and dysphagia (50%). The typical length of the styloid process ranges from 25 to 30 mm; however, [ 18 F]NaF (sodium fluoride) PET/CT showed elongated styloid processes with an average length of 52.1 ± 15.6 mm (mean ± SD) with increased turnover at the base of one of the styloid processes. The removed styloid processes were further examined by histology, micro-CT, quantitative backscatter electron imaging (qBEI), Fourier transform infrared spectroscopy (FTIR), and circularly polarized light imaging. Histology revealed one case of a fractured styloid process healing through callus formation and one case of pseudarthrosis. Bone mineral density and mineralization was similar in the styloid processes when compared to cortical bone samples derived from the mandibular bone of different patients. Circular polarized light microscopy showed a collagen orientation in the styloid process comparable to the cortical bone samples with a distinct separation of collagen structure between the mineralized structure and the surrounding soft tissue with FTIR analysis demonstrating a typical composition of bone. This altogether suggests that the elongated styloid processes in Eagle syndrome are mature bone, capable of endochondral repair, possibly growing from the base of the process through endochondral ossification, rather than being a form of secondary calcification of the stylohyoid ligament as previously postulated., Competing Interests: No authors have conflicts of interest to disclose., (© The Author(s) 2024. Published by Oxford University Press on behalf of the American Society for Bone and Mineral Research.)

Introduction: Osteogenesis imperfecta (OI) is a rare genetic disorder characterized by bone fragility. While skeletal manifestations are well documented, few studies have explored the effect of OI on the fetal heart. This retrospective case series investigates cardiac pathology in OI type II fetuses, aiming to address this gap., Methods: Medical records and autopsy reports of 6 genetically confirmed OI type II cases were examined. Fetuses had pathogenic variants in COL1A1 or PPIB , inducing structural defects in collagen type I. In addition to hematoxylin and eosin and Elastic van Gieson staining, the expression of collagen type I, COL1A1 and COL1A2 chains was examined by immunohistochemistry., Results: Immunohistochemistry confirmed robust expression of collagen type I throughout the heart. Five fetuses had normal heart weight, while 1 had a low heart weight in the context of generalized growth retardation. None displayed structural heart anomalies., Conclusion: This study reveals robust collagen type I expression in the hearts of OI type II fetuses without structural anomalies. We hypothesize that collagen type I abnormalities may not be causative factors for heart anomalies during early embryonic development. Instead, their impact may be conceivably related to an increased susceptibility to degenerative changes later in life., Competing Interests: Declaration of Conflicting InterestsThe author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Background: Fibrodysplasia Ossificans Progressiva (FOP) is a rare, genetic disease in which heterotopic bone is formed in muscles, tendons and ligaments throughout the body. Disease progression is variable over time and between individuals. 18 F-fluoride uptake in newly formed bone can be evaluated using [ 18 F]NaF (i.e., sodiumfluoride) PET/CT, identifying active areas of bone formation in FOP. The purpose of this study was to assess the performance of various semi-quantitative methods with full kinetic analysis., Results: Seven patients (age range: 20-31 years) with FOP underwent dynamic [ 18 F]NaF scans at baseline and after one year. [ 18 F]NaF uptake was measured in aorta descendens, vertebrae, heterotopic bone lesions and metabolically active regions on PET, and quantified using nonlinear regression (NLR) analysis together with standardized uptake value (SUV) and target-to-blood ratio (TBR). SUV was on measured the 40-45 min frame of the dynamic sequence (SUV 40-45 ) and on the subsequent static sweep (SUV Static ). Correlations between and SUV 40-45 and NLR-derived K i were comparable when normalized to body weight ( r  = 0.81, 95% CI 0.64-0.90), lean body mass ( r  = 0.79, 95% CI 0.61-0.89) and body surface area ( r  = 0.84, 95% CI 0.70-0.92). Correlation between TBR 40-45 and NLR-derived K i ( r  = 0.92, 95% CI 0.85-0.96) was higher than for SUV 40-45 . Correlation between TBR 40-45 and NLR-derived K i was similar at baseline and after one year ( r  = 0.93 and 0.94). The change in TBR 40-45 between baseline measurement and after one year correlated best with the change in NLR-derived K i in the PET-active lesions ( r  = 0.87)., Conclusion: The present data supports the use of TBR for assessing fluoride uptake in PET-active lesions in FOP., Clinical Trial Registration: Sub-study of the Lumina-1 trial (clinicaltrials.gov, NCT03188666, registered 13-06-2017)., Competing Interests: DGT was employed by Regeneron Pharmaceuticals, Inc. EE reports that Amsterdam UMC receives subsidies/financing FOP research from the Dutch FOP Patient Foundation, IFOPA, Regeneron Pharmaceuticals Inc., EU-IMI (AstraZeneca), and Clementia/ Ipsen; non-paid board memberships for the International Clinical Council on FOP, the IFOPA registry advisory board, and the Dutch Society for Endocrinology Bone; chair of the Rare Bone Expert Center and member of the steering committee of Amsterdam Bone Center, European FOP consortium; and being a member of European Reference Network on rare bone diseases (ERN BOND) and of an American Society for Bone and Mineral Research committee. The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest. The authors declare that this study received funding from Regeneron Pharmaceuticals, Inc. The funder had the following involvement in the study: study design and collection, analysis and interpretation of data. The funder was not involved in the writing of this article, or the decision to submit it for publication. The author(s) declared that they were an editorial board member of Frontiers, at the time of submission. This had no impact on the peer review process and the final decision., (© 2024 de Ruiter, Botman, Teunissen, Lammertsma, Boellaard, Raijmakers, Schwarte, Nieuwenhuijzen, Gonzalez Trotter, Eekhoff and Yaqub.)

(1) Mesenchymal stem cells (MSCs) are a valuable cell model to study the bone pathology of Osteogenesis Imperfecta (OI), a rare genetic collagen-related disorder characterized by bone fragility and skeletal dysplasia. We aimed to generate a novel OI induced mesenchymal stem cell (iMSC) model from induced pluripotent stem cells (iPSCs) derived from human dermal fibroblasts. For the first time, OI iMSCs generation was based on an intermediate neural crest cell (iNCC) stage. (2) Skin fibroblasts from healthy individuals and OI patients were reprogrammed into iPSCs and subsequently differentiated into iMSCs via iNCCs. (3) Successful generation of iPSCs from acquired fibroblasts was confirmed with changes in cell morphology, expression of iPSC markers SOX2 , NANOG , and OCT4 and three germ-layer tests. Following differentiation into iNCCs, cells presented increased iNCC markers including P75NTR , TFAP2A , and HNK-1 and decreased iPSC markers, shown to reach the iNCC stage. Induction into iMSCs was confirmed by the presence of CD73 , CD105 , and CD90 markers, low expression of the hematopoietic, and reduced expression of the iNCC markers. iMSCs were trilineage differentiation-competent, confirmed using molecular analyses and staining for cell-type-specific osteoblast, adipocyte, and chondrocyte markers. (4) In the current study, we have developed a multipotent in vitro iMSC model of OI patients and healthy controls able to differentiate into osteoblast-like cells.

Osteogenesis imperfecta (OI) is a rare genetic disorder caused by abnormal collagen type I production. While OI is primarily characterized by bone fragility and deformities, patients also have extraskeletal manifestations, including an increased risk of cardiovascular disease. This review provides a comprehensive overview of the literature on cardiovascular diseases in OI patients in order to raise awareness of this understudied clinical aspect of OI and support clinical guidelines. In accordance with the PRISMA guidelines, a systematic literature search in PubMed, Embase, Web of Science and Scopus was conducted that included articles from the inception of these databases to April 2023. Valvular disease, heart failure, atrial fibrillation, and hypertension appear to be more prevalent in OI than in control individuals. Moreover, a larger aortic root was observed in OI compared to controls. Various cardiovascular diseases appear to be more prevalent in OI than in controls. These cardiovascular abnormalities are observed in all types of OI and at all ages, including young children. As there are insufficient longitudinal studies, it is unknown whether these abnormalities are progressive in nature in OI patients. Based on these findings, we would recommend referring individuals with OI to a cardiologist with a low-threshold., (© 2024. The Author(s).)

Here, we report the clinical pharmacology data from LUMINA-1 (NCT03188666), a Phase 2 trial that evaluated garetosmab (a monoclonal antibody against activin A) in patients with fibrodysplasia ossificans progressiva. Forty-four patients were randomly assigned to intravenous 10 mg/kg of garetosmab or placebo every 4 weeks in a double-blind 28-week treatment period, followed by a 28-week open-label treatment period with garetosmab, and subsequent open-label extension. Serum samples were obtained to assess pharmacokinetics (PK), immunogenicity, and bone morphogenetic protein 9 (BMP9). Comparative exposure-response analyses for efficacy and safety were performed with trough concentrations (C trough ) of garetosmab prior to dosing. Steady-state PK was reached 12-16 weeks after the first dose of garetosmab, with mean (standard deviation) C trough of 105 ± 30.8 mg/L. Immunogenicity assessments showed anti-garetosmab antibody formation in 1 patient (1/43; 2.3%); titers were low, and did not affect PK or clinical efficacy. Median concentrations of BMP9 in serum were approximately 40 pg/mL at baseline. There were no meaningful differences in PK or BMP9 concentration-time profiles between patients who did and did not experience epistaxis or death. The comparative exposure-response analyses demonstrated no association between C trough and efficacy or safety. PK findings were consistent with prior data in healthy volunteers and were typical for a monoclonal antibody administered at doses sufficient to saturate target-mediated clearance. There were no trends that suggested patients with higher serum exposures to garetosmab were more likely to experience a reduction in heterotopic ossification or adverse events. Garetosmab is being further evaluated in the Phase 3 OPTIMA trial., (© 2023 Regeneron Pharmaceuticals, Inc and The Authors. The Journal of Clinical Pharmacology published by Wiley Periodicals LLC on behalf of American College of Clinical Pharmacology.)

Introduction: Respiratory insufficiency is a leading cause of death in individuals with osteogenesis imperfecta (OI). However, evaluating pulmonary function in OI presents challenges. Commonly used pulmonary function tests such as spirometry and body plethysmography are sometimes difficult to perform for OI patients, and reference intervals are not always applicable. The forced oscillation technique (FOT) is a patient-friendly method for detecting respiratory abnormalities that requires no effort from the patient., Objective: This study investigates the feasibility of FOT in the evaluation of respiratory function in the clinical management of OI patients., Methods: Twelve OI patients, comprising eight with Sillence OI I, two with OI IV, and two with OI III, underwent spirometry, body plethysmography, and FOT, both pre-and post-administration of salbutamol., Results: FOT measurements exhibited consistent trends that aligned with spirometry and body plethysmography findings. The resistance at 8 Hz decreased after the administration of salbutamol, indicating that FOT is able to detect bronchial obstruction and its alleviation by medication ( p  < 0.05). The resonant frequency during expiration was higher than during inspiration in nearly all patients, suggesting obstructive disease. The technique gives insight into both inspiratory and expiratory impairment of pulmonary ventilation. The main FOT parameters showed a relatively high repeatability in duplicate measurements., Conclusion: Bronchial obstruction can be detected by FOT in patients with OI during quiet breathing, making it an easily executable alternative to other lung function measurements. The technique can detect the bronchodilator effect of sympathomimetic medication. It has the potential to provide information on expiratory flow limitation, pulmonary restriction, and reduced lung compliance., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2023 Storoni, Verdonk, Micha, Jak, Bugiani, Eekhoff and van den Aardweg.)

Background: Fibrodysplasia ossificans progressiva (FOP) is an ultrarare genetic disorder with episodic and progressive heterotopic ossification. Tissue trauma is a major risk factor for flareups, heterotopic ossification (HO), and loss of mobility in patients with FOP. The International Clinical Council on FOP generally recommends avoiding surgery in patients with FOP unless the situation is life-threatening, because soft tissue injury can trigger an FOP flareup. Surprisingly little is known about flareups, HO formation, and loss of mobility after fractures of the normotopic (occurring in the normal place, distinct from heterotopic) skeleton when treated nonoperatively in patients with FOP., Questions/purposes: (1) What proportion of fractures had radiographic evidence of union (defined as radiographic evidence of healing at 6 weeks) or nonunion (defined as the radiographic absence of a bridging callus at 3 years after the fracture)? (2) What proportion of patients had clinical symptoms of an FOP flareup because of the fracture (defined by increased pain or swelling at the fracture site within several days after closed immobilization)? (3) What proportion of patients with fractures had radiographic evidence of HO? (4) What proportion of patients lost movement after a fracture?, Methods: We retrospectively identified 36 patients with FOP from five continents who sustained 48 fractures of the normotopic skeleton from January 2001 to February 2021, who were treated nonoperatively, and who were followed for a minimum of 18 months after the fracture and for as long as 20 years, depending on when they sustained their fracture during the study period. Five patients (seven fractures) were excluded from the analysis to minimize cotreatment bias because these patients were enrolled in palovarotene clinical trials (NCT02190747 and NCT03312634) at the time of their fractures. Thus, we analyzed 31 patients (13 male, 18 female, median age 22 years, range 5 to 57 years) who sustained 41 fractures of the normotopic skeleton that were treated nonoperatively. Patients were analyzed at a median follow-up of 6 years (range 18 months to 20 years), and none was lost to follow-up. Clinical records for each patient were reviewed by the referring physician-author and the following data for each fracture were recorded: biological sex, ACVR1 gene pathogenic variant, age at the time of fracture, fracture mechanism, fracture location, initial treatment modality, prednisone use at the time of the fracture as indicated in the FOP Treatment Guidelines for flare prevention (2 mg/kg once daily for 4 days), patient-reported flareups (episodic inflammatory lesions of muscle and deep soft connective tissue characterized variably by swelling, escalating pain, stiffness, and immobility) after the fracture, follow-up radiographs of the fracture if available, HO formation (yes or no) as a result of the fracture determined at a minimum of 6 weeks after the fracture, and patient-reported loss of motion at least 6 months after and as long as 20 years after the fracture. Postfracture radiographs were available in 76% (31 of 41) of fractures in 25 patients and were independently reviewed by the referring physician-author and senior author for radiographic criteria of fracture healing and HO., Results: Radiographic healing was noted in 97% (30 of 31) of fractures at 6 weeks after the incident fracture. Painless nonunion was noted in one patient who sustained a displaced patellar fracture and HO. In seven percent (three of 41) of fractures, patients reported increased pain or swelling at or near the fracture site within several days after fracture immobilization that likely indicated a site-specific FOP flareup. The same three patients reported a residual loss of motion 1 year after the fracture compared with their prefracture status. HO developed in 10% (three of 31) of the fractures for which follow-up radiographs were available. Patient-reported loss of motion occurred in 10% (four of 41) of fractures. Two of the four patients reported noticeable loss of motion and the other two patients reported that the joint was completely immobile (ankylosis)., Conclusion: Most fractures treated nonoperatively in individuals with FOP healed with few flareups, little or no HO, and preservation of mobility, suggesting an uncoupling of fracture repair and HO, which are two inflammation-induced processes of endochondral ossification. These findings underscore the importance of considering nonoperative treatment for fractures in individuals with FOP. Physicians who treat fractures in patients with FOP should consult with a member of the International Clinical Council listed in the FOP Treatment Guidelines ( https://www.iccfop.org )., Level of Evidence: Level IV, therapeutic study., Competing Interests: All ICMJE Conflict of Interest Forms for authors and Clinical Orthopaedics and Related Research ® editors and board members are on file with the publication and can be viewed on request., (Copyright © 2023 by the Association of Bone and Joint Surgeons.)

Pathogenic variants in SPARC cause a rare autosomal recessive form of osteogenesis imperfecta (OI), classified as OI type XVII, which was first reported in 2015. Only six patient cases with this specific form of OI have been reported to date. The SPARC protein plays a crucial role in the calcification of collagen in bone, synthesis of the extracellular matrix, and the regulation of cell shape. In this case report, we describe the phenotype of two patients with SPARC-related OI, including a patient with two novel pathogenic variants in the SPARC gene. Targeted Next Generation Sequencing revealed new compound heterozygous variants (c.484G > A p.(Glu162Lys)) and c.496C > T p.(Arg166Cys)) in one patient and a homozygous nonsense pathogenic variant (c.145C > T p.(Gln49*)) in the other. In line with previously reported cases, the two OI patients presented delayed motor development, muscular weakness, scoliosis, and multiple fractures. Interestingly, our study reports for the first time the occurrence of dentinogenesis imperfecta. The study also reports the effectiveness of bisphosphonate treatment for OI type XVII. This article enhances the genetic, clinical, therapeutic, and radiological understanding of SPARC-related OI., Competing Interests: Declaration of competing interest The authors declare no conflicts of interest., (Copyright © 2023 The Authors. Published by Elsevier Masson SAS.. All rights reserved.)

Fibrodysplasia ossificans progressiva (FOP) is a rare disease characterized by heterotopic ossification (HO) in connective tissues and painful flare-ups. In the phase 2 LUMINA-1 trial, adult patients with FOP were randomized to garetosmab, an activin A-blocking antibody (n = 20) or placebo (n = 24) in period 1 (28 weeks), followed by an open-label period 2 (28 weeks; n = 43). The primary end points were safety and for period 1, the activity and size of HO lesions. All patients experienced at least one treatment-emergent adverse event during period 1, notably epistaxis, madarosis and skin abscesses. Five deaths (5 of 44; 11.4%) occurred in the open-label period and, while considered unlikely to be related, causality cannot be ruled out. The primary efficacy end point in period 1 (total lesion activity by PET-CT) was not met (P = 0.0741). As the development of new HO lesions was suppressed in period 1, the primary efficacy end point in period 2 was prospectively changed to the number of new HO lesions versus period 1. No placebo patients crossing over to garetosmab developed new HO lesions (0% in period 2 versus 40.9% in period 1; P = 0.0027). Further investigation of garetosmab in FOP is ongoing. ClinicalTrials.gov identifier NCT03188666 ., (© 2023. The Author(s).)

Pathogenic variants in the LRP5, PLS3, or WNT1 genes can significantly affect bone mineral density, causing monogenic osteoporosis. Much remains to be discovered about the phenotype and medical care needs of these patients. The purpose of this study was to examine the use of medical care among Dutch individuals identified between 2014 and 2021 with a pathogenic or suspicious rare variant in LRP5, PLS3, or WNT1. In addition, the aim was to compare their medical care utilization to both the overall Dutch population and the Dutch Osteogenesis Imperfecta (OI) population. The Amsterdam UMC Genome Database was used to match 92 patients with the Statistics Netherlands (CBS) cohort. Patients were categorized based on their harbored variants: LRP5, PLS3, or WNT1. Hospital admissions, outpatient visits, medication data, and diagnosis treatment combinations (DTCs) were compared between the variant groups and, when possible, to the total population and OI population. Compared to the total population, patients with an LRP5, PLS3, or WNT1 variant had 1.63 times more hospital admissions, 2.0 times more opened DTCs, and a greater proportion using medication. Compared to OI patients, they had 0.62 times fewer admissions. Dutch patients with an LRP5, PLS3, or WNT1 variant appear to require on average more medical care than the total population. As expected, they made higher use of care at the surgical and orthopedic departments. Additionally, they used more care at the audiological centers and the otorhinolaryngology (ENT) department, suggesting a higher risk of hearing-related problems., (© 2023. The Author(s).)

Since our discovery in 2013 that genetic defects in PLS3 lead to bone fragility, the mechanistic details of this process have remained obscure. It has been established that PLS3 variants cause syndromic and nonsyndromic osteoporosis as well as osteoarthritis. PLS3 codes for an actin-bundling protein with a broad pattern of expression. As such, it is puzzling how PLS3 specifically leads to bone-related disease presentation. Our review aims to summarize the current state of knowledge regarding the function of PLS3 in the predominant cell types in the bone tissue, the osteocytes, osteoblasts and osteoclasts. This is related to the role of PLS3 in regulating mechanotransduction, calcium regulation, vesicle trafficking, cell differentiation and mineralization as part of the complex bone pathology presented by PLS3 defects. Considering the consequences of PLS3 defects on multiple aspects of bone tissue metabolism, our review motivates the study of its mechanism in bone diseases which can potentially help in the design of suitable therapy., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2023 Zhong, Pathak, Liang, Zhytnik, Pals, Eekhoff, Bravenboer and Micha.)

Pulmonary hypoplasia and respiratory failure are primary causes of death in patients with osteogenesis imperfecta (OI) type II. OI is a genetic skeletal disorder caused by pathogenic variants in genes encoding collagen type I. It is still unknown if the collagen defect also affects lung development and structure, causing lung hypoplasia in OI type II. The aim of this study was to investigate the intrinsic characteristics of OI embryonic lung parenchyma and to determine whether altered collagen type I may compromise airway development and lung structure. Lung tissue from nine fetuses with OI type II and six control fetuses, matched by gestational age, was analyzed for TTF-1 and collagen type I expression by immunohistochemistry, to evaluate the state of lung development and amount of collagen. The differentiation of epithelium into type 2 pneumocytes during embryonic development was premature in OI type II fetuses compared to controls (p < 0.05). Collagen type I showed no significant differences between the two groups. However, the amount of alpha2(I) chains was higher in fetuses with OI and the ratio of alpha1(I) to alpha2(I) lower in OI compared to controls. Cell differentiation during lung embryonic development in patients with OI type II is premature and impaired. This may be the underlying cause of pulmonary hypoplasia. Altered cell differentiation can be secondary to mechanical chest factors or a consequence of disrupted type I collagen synthesis. Our findings suggest that collagen type I is a biochemical regulator of pulmonary cell differentiation, influencing lung development., (© 2023 The Authors. Physiological Reports published by Wiley Periodicals LLC on behalf of The Physiological Society and the American Physiological Society.)

Pregnancy- and lactation-associated osteoporosis (PLO) is a rare form of osteoporosis, of which the pathogenesis and best treatment options are unclear. In this report, we describe the case of a 34-year old woman diagnosed with severe osteoporosis and multiple vertebral fractures after her first pregnancy, who was subsequently treated with teriparatide (TPTD) and zoledronic acid (ZA). We describe the clinical features, imaging examination, and genetic analysis. Substantial improvements were observed in areal and volumetric bone mineral density (BMD), microarchitecture, and strength between 7 and 40 months postpartum as assessed by dual-energy X-ray absorptiometry at the total hip and spine and by high-resolution peripheral quantitative CT at the distal radius and tibiae. At the hip, spine, and distal radius, these improvements were mainly enabled by treatment with TPTD and ZA, while at the distal tibiae, physiological recovery and postpartum physiotherapy due to leg pain after stumbling may have played a major role. Additionally, the findings show that, despite the improvements, BMD, microarchitecture, and strength remained severely impaired in comparison with healthy age- and gender-matched controls at 40 months postpartum. Genetic analysis showed no monogenic cause for osteoporosis, and it is suggested that PLO in this woman could have a polygenic origin with possible susceptibility based on familiar occurrence of osteoporosis., (© 2023. The Author(s).)

Introduction: Pulmonary involvement in Osteogenesis Imperfecta (OI) can be severe but may be overlooked in milder cases. The Care4BrittleBones Foundation initiated this project to develop a set of global outcome measures focusing on respiratory-related issues in patients with OI. The objective was to reach an international consensus for a standardized set of outcomes and associated measuring instruments for the pulmonary care of individuals with OI. Based on the initial tests and questionnaires, we suggest parameters for when pulmonologists should seek guidance from the growing literature on OI pulmonary care and/or recognized experts in the field., Study Design and Methods: The project team consisted of a multidisciplinary mix of 12 people from six countries, including an OI patient representative, and facilitated by the Care4BrittleBones Foundation director. The International Consortium for Health Outcomes Measurement (ICHOM) process was followed, which includes the Delphi method, used to collect the opinions of the expert team. Patient input was present in each meeting due to the inclusion of a patient representative. In addition, online focus groups were held. They consisted of adults with OI from different countries, and they determined which questions matter the most to the OI community worldwide., Results: After three Delphi rounds, the expert team reached a consensus on the final set of measuring instruments, which included pulmonary function testing and patient self-reporting of symptoms related to breathing and sleep. Two questionnaires were decided upon: St. George's Respiratory Questionnaire (shortened version) and four questions regarding sleep. Patients should be screened for a history of pneumonia. Advanced testing for select patients by a pulmonologist would include further pulmonary function tests and a chest radiograph., Conclusions: A standardized set of outcome measures related to pulmonary care of individuals with OI was determined based on what is important to both experts and patients. This included patient-reported outcome measures and basic pulmonary function testing. Using these outcome measures, it can be determined which patients are at high risk for pulmonary complications., (Copyright © 2023 American College of Chest Physicians. Published by Elsevier Inc. All rights reserved.)

Fibrodysplasia Ossificans Progressiva (FOP) is a very rare genetic disease characterized by progressive heterotopic ossification (HO) of soft tissues, leading to immobility and premature death. FOP is caused by a mutation in the Activin receptor Type 1 (ACVR1) gene, resulting in altered responsiveness to Activin-A. We recently revealed that Activin-A induces fewer, but larger and more active, osteoclasts regardless of the presence of the mutated ACVR1 receptor. The underlying mechanism of Activin-A-induced changes in osteoclastogenesis at the gene expression level remains unknown. Transcriptomic changes induced by Activin-A during osteoclast formation from healthy controls and patient-derived CD14-positive monocytes were studied using RNA sequencing. CD14-positive monocytes from six FOP patients and six age- and sex-matched healthy controls were differentiated into osteoclasts in the absence or presence of Activin-A. RNA samples were isolated after 14 days of culturing and analyzed by RNA sequencing. Non-supervised principal component analysis (PCA) showed that samples from the same culture conditions (e.g., without or with Activin-A) tended to cluster, indicating that the variability induced by Activin-A treatment was larger than the variability between the control and FOP samples. RNA sequencing analysis revealed 1480 differentially expressed genes induced by Activin-A in healthy control and FOP osteoclasts with p (adj) < 0.01 and a Log2 fold change of ≥±2. Pathway and gene ontology enrichment analysis revealed several significantly enriched pathways for genes upregulated by Activin-A that could be linked to the differentiation or function of osteoclasts, cell fusion or inflammation. Our data showed that Activin-A has a substantial effect on gene expression during osteoclast formation and that this effect occurred regardless of the presence of the mutated ACVR1 receptor causing FOP.

Introduction: Osteogenesis Imperfecta is a rare genetic connective tissue disorder, characterized by skeletal dysplasia and fragile bones. Currently only two mouse models have been reported for haploinsufficient (HI) mild Osteogenesis Imperfecta (OI); the Col1a1 +/Mov13 (Mov13) and the Col1a1 +/-365 mouse model. The Mov13 mice were created by random insertion of the Mouse Moloney leukemia virus in the first intron of the Col1a1 gene, preventing the initiation of transcription. Since the development of the Mov13 mice almost four decades ago and its basic phenotypic characterization in the 90s, there have not been many further studies. We aimed to extensively characterize the Mov13 mouse model in order to critically evaluate its possible use for preclinical studies of HI OI., Methods: Bone tissue from ten heterozygous Mov13 and ten wild-type littermates (WT) C57BL/6J mice (50% males per group) was analyzed at eight weeks of age with bone histomorphometry, micro computed tomography (microCT), 3-point bending, gene expression of different collagens, as well as serum markers of bone turnover., Results: The Mov13 mouse presented a lower bone strength and impaired material properties based on our results of 3-point bending and microCT analysis respectively. In contrast, no significant differences were found for all histomorphometric parameters. In addition, no significant differences in Col1a1 bone expression were present, but there was a significant lower P1NP concentration, a bone formation marker, measured in serum. Furthermore, bone tissue of Mov13 mice presented significantly higher expression of collagens ( Col1a2 , Col5a1 and Col5a2 ), and bone metabolism markers ( Bglap , Fgf23 , Smad7 , Edn1 and Eln ) compared to WT. Finally, we measured a significantly lower Col1a1 expression in heart and skin tissue and also determined a higher expression of other collagens in the heart tissue., Conclusion: Although we did not detect a significant reduction in Col1a1 expression in the bone tissue, a change in bone structure and reduction in bone strength was noted. Regrettably, the variability of the bone phenotype and the appearance of severe lymphoma in adult Mov13 mice, does not favor their use for the testing of new long-term drug studies. As such, a new HI OI type 1 mouse model is urgently needed., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2023 Claeys, Zhytnik, Wisse, van Essen, Eekhoff, Pals, Bravenboer and Micha.)

Osteogenesis imperfecta (OI) is a heritable connective tissue disorder that causes bone fragility due to pathogenic variants in genes responsible for the synthesis of type I collagen. Efforts to classify the high clinical variability in OI led to the Sillence classification. However, this classification only partially takes into account extraskeletal manifestations and the high genetic variability. Little is known about the relation between genetic variants and phenotype as of yet. The aim of the study was to create a clinically relevant genetic stratification of a cohort of 675 Dutch OI patients based on their pathogenic variant types and to provide an overview of their respective medical care demands. The clinical records of 675 OI patients were extracted from the Amsterdam UMC Genome Database and matched with the records from Statistics Netherlands (CBS). The patients were categorized based on their harbored pathogenic variant. The information on hospital admissions, outpatient clinic visits, medication, and diagnosis-treatment combinations (DTCs) was compared between the variant groups. OI patients in the Netherlands appear to have a higher number of DTCs, outpatient clinic visits, and hospital admissions when compared to the general Dutch population. Furthermore, medication usage seems higher in the OI cohort in comparison to the general population. The patients with a COL1A1 or COL1A2 dominant negative missense non-glycine substitution appear to have a lower health care need compared to the other groups, and even lower than patients with COL1A1 or COL1A2 haploinsufficiency. It would be useful to include the variant type in addition to the Sillence classification when categorizing a patient's phenotype.

Fibrodysplasia ossificans progressiva (FOP) is a catastrophic, ultra-rare disease of heterotopic ossification caused by genetic defects in the ACVR1 gene. The mutant ACVR1 receptor, when triggered by an inflammatory process, leads to heterotopic ossification of the muscles and ligaments. Activin A has been discovered as the main osteogenic ligand of the FOP ACVR1 receptor. However, the source of Activin A itself and the trigger of its production in FOP individuals have remained elusive. We used primary dermal fibroblasts from five FOP patients to investigate Activin A production and how this is influenced by inflammatory cytokines in FOP. FOP fibroblasts showed elevated Activin A production compared to healthy controls, both in standard culture and osteogenic transdifferentiation conditions. We discovered TGFβ1 to be an FOP-specific stimulant of Activin A, shown by the upregulation of the INHBA gene and protein expression. Activin A and TGFβ1 were both induced by BMP4 in FOP and control fibroblasts. Treatment with TNFα and IL6 produced negligible levels of Activin A and TGFβ1 in both cell groups. We present for the first time TGFβ1 as a triggering factor of Activin A production in FOP. As TGFβ1 can promote the induction of the main driver of FOP, TGFβ1 could also be considered a possible therapeutic target in FOP treatment.

Fibroblasts have an important role in the maintenance of the extracellular matrix of connective tissues by producing and remodelling extracellular matrix proteins. They are indispensable for physiological processes, and as such also associate with many pathological conditions. In recent years, a number of studies have identified donor-derived fibroblasts in various tissues of bone marrow transplant recipients, while others could not replicate these findings. In this systematic review, we provide an overview of the current literature regarding the differentiation of hematopoietic stem cells into fibroblasts in various tissues. PubMed, Embase, and Web of Science (Core Collection) were systematically searched for original articles concerning fibroblast origin after hematopoietic stem cell transplantation in collaboration with a medical information specialist. Our search found 5421 studies, of which 151 were analysed for full-text analysis by two authors independently, resulting in the inclusion of 104 studies. Only studies in animals and humans, in which at least one marker was used for fibroblast identification, were included. The results were described per organ of fibroblast engraftment. We show that nearly all mouse and human organs show evidence of fibroblasts of hematopoietic stem cell transfer origin. Despite significant heterogeneity in the included studies, most demonstrate a significant presence of fibroblasts of hematopoietic lineage in non-hematopoietic tissues. This presence appears to increase after the occurrence of tissue damage., Competing Interests: The authors declare that they have no conflicts of interest.

Inherited bone disorders account for about 10% of documented Mendelian disorders and are associated with high financial burden. Their study requires osteoblasts which play a critical role in regulating the development and maintenance of bone tissue. However, bone tissue is not always available from patients. We developed a highly efficient platelet lysate-based approach to directly transdifferentiate skin-derived human fibroblasts to osteoblast-like cells. We extensively characterized our in vitro model by examining the expression of osteoblast-specific markers during the transdifferentiation process both at the mRNA and protein level. The transdifferentiated osteoblast-like cells showed significantly increased expression of a panel of osteogenic markers. Mineral deposition and ALP activity were also shown, confirming their osteogenic properties. RNA-seq analysis allowed the global study of changes in the transcriptome of the transdifferentiated cells. The transdifferentiated cells clustered separately from the primary fibroblasts with regard to the significantly upregulated genes indicating a distinct transcriptome profile; transdifferentiated osteoblasts also showed significant enrichment in gene expression related to skeletal development and bone mineralization. Our presented in vitro model may potentially contribute to the prospect of studying osteoblast-dependent disorders in patient-derived cells., (© 2022. The Author(s).)

Fibrodysplasia ossificans progressiva (FOP) is a rare and devastating genetic disease, in which soft connective tissue is converted into heterotopic bone through an endochondral ossification process. Patients succumb early as they gradually become trapped in a second skeleton of heterotopic bone. Although the underlying genetic defect is long known, the inherent complexity of the disease has hindered the discovery of effective preventions and treatments. New developments in the gene therapy field have motivated its consideration as an attractive therapeutic option for FOP. However, the immune system's role in FOP activation and the as-yet unknown primary causative cell, are crucial issues which must be taken into account in the therapy design. While gene therapy offers a potential therapeutic solution, more knowledge about FOP is needed to enable its optimal and safe application.

Background: Fibrodysplasia Ossificans Progressiva (FOP) is a genetic, progressive and devastating disease characterized by severe heterotopic ossification (HO), loss of mobility and early death. There are no FDA approved medications. The STOPFOP team identified AZD0530 (saracatinib) as a potent inhibitor of the ALK2/ACVR1-kinase which is the causative gene for this rare bone disease. AZD0530 was proven to prevent HO formation in FOP mouse models. The STOPFOP trial investigates the repositioning of AZD0530, originally developed for ovarian cancer treatment, to treat patients with FOP., Methods: The STOPFOP trial is a phase 2a study. It is designed as a European, multicentre, 6-month double blind randomized controlled trial of AZD0530 versus placebo, followed by a 12-month trial comparing open-label extended AZD0530 treatment with natural history data as a control. Enrollment will include 20 FOP patients, aged 18-65 years, with the classic FOP mutation (ALK2 R206H). The primary endpoint is objective change in heterotopic bone volume measured by low-dose whole-body computer tomography (CT) in the RCT phase. Secondary endpoints include 18 F NaF PET activity and patient reported outcome measures., Discussion: Clinical trials in rare diseases with limited study populations pose unique challenges. An ideal solution for limiting risks in early clinical studies is drug repositioning - using existing clinical molecules for new disease indications. Using existing assets may also allow a more fluid transition into clinical practice. With positive study outcome, AZD0530 may provide a therapy for FOP that can be rapidly progressed due to the availability of existing safety data from 28 registered clinical trials with AZD0530 involving over 600 patients., Trial Registration: EudraCT, 2019-003324-20. Registered 16 October 2019, https://www.clinicaltrialsregister.eu/ctr-search/trial/2019-003324-20/NL ., Clinicaltrials: gov , NCT04307953 . Registered 13 March 2020., (© 2022. The Author(s).)

Osteogenesis Imperfecta (OI) is a complex disease caused by genetic alterations in production of collagen type I, and collagen-related proteins. Bone fragility is the most common patient issue, but extraskeletal complications also present an adverse factor in the quality of life and prognosis of patients with OI. However, still little is known about the morbidity and mortality of these patients. The objective of this paper is to determine and describe to what extent OI impacts patients' life in terms of hospitalization and complications describing the incidence and prevalence of the Dutch cohort of OI patients and the characteristics of their hospital admissions. Information regarding OI patients and their hospital admission was extracted from the Statistics Netherlands Database and matched to the OI Genetics Database of Amsterdam UMC. Hospital admission data was available for 674 OI patients. This OI nationwide registry study shows that the life expectancy of OI patients is adversely affected by the disease. The median annual incidence risk of OI between 1992 and 2019 was 6.5 per 100,000 live births. Furthermore, patients with OI had a 2.9 times higher hospitalization rate compared to the general Dutch population. The highest hospitalization rate ratio of 8.4 was reported in the patient group between 0 and 19 years old. OI type and severity had impact on extraskeletal manifestations, which play a key role in the numerous hospital admissions. More awareness about the impact of OI on patients' life is needed to improve and implement prevention and follow-up guidelines., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest. The reviewer OS declared a past co-authorship with one of the authors EE to the handling editor., (Copyright © 2022 Storoni, Treurniet, Maugeri, Pals, van den Aardweg, van der Pas, Elting, Kloen, Micha and Eekhoff.)

Background: Presurgical treatment with an α-adrenergic receptor blocker is recommended to antagonize the catecholamine-induced α-adrenergic receptor mediated vasoconstriction in patients with pheochromocytoma or sympathetic paraganglioma (PPGL). There is, however, a considerable interindividual variation in the dose-response relationship regarding the magnitude of blood pressure reduction or the occurrence of side effects. We hypothesized that genetically determined differences in α-adrenergic receptor activity contribute to this variability in dose-response relationship. Methods: Thirty-one single-nucleotide polymorphisms (SNPs) of the α1A, α1B, α1D adrenoreceptor (ADRA1A, ADRA1B, ADRA1D) and α2A, α2B adrenoreceptor (ADRA2A, ADRA2B) genes were genotyped in a group of 116 participants of the PRESCRIPT study. Haplotypes were constructed after determining linkage disequilibrium blocks. Results: The ADRA1B SNP rs10515807 and the ADRA2A SNPs rs553668/rs521674 were associated with higher dosages of α-adrenergic receptor blocker (p < 0.05) and with a higher occurrence of side effects (rs10515807) (p = 0.005). Similar associations were found for haplotype block 6, which is predominantly defined by rs10515807. Conclusions: This study suggests that genetic variability of α-adrenergic receptor genes might be associated with the clinically observed variation in beneficial and adverse therapeutic drug responses to α-adrenergic receptor blockers. Further studies in larger cohorts are needed to confirm our observations.

Fibrodysplasia ossificans progressiva (FOP) is a rare genetic disorder characterized by heterotopic ossification (HO) of the skeletal muscles, fascia, tendons and ligaments. Patients often experience limitations in jaw function due to HO formation in the maxillofacial region. However, no studies have yet analyzed the age of onset and location of HO and the type of restrictions it may yield in the maxillofacial region. The aim of this study was to evaluate all existing literature on the site of onset of HO and associated functional restrictions of the jaw. To this end, a scoping review was performed focusing on limitations of jaw movement in FOP patients. The literature search resulted in 725 articles, of which 30 articles were included for full study after applying the exclusion criteria. From these articles 94 FOP patients were evaluated for gender, age, presence and age at which HO started in the maxillofacial region, location of HO, whether HO was caused spontaneous or traumatic and maximum mouth opening. Formation of HO is slightly more common in female patients compared to male patients, but the age of HO onset or the maximum mouth opening does not differ between genders. Trauma-induced HO occurred at a significantly younger age than spontaneous HO. Interestingly, a difference in maximum mouth opening was observed between the different ossified locations in the maxillofacial region, with ossification of the masseter muscle resulting in the smallest and ossification of the zygomatic arch resulting in the largest maximum mouth opening. This review revealed that the location of the maxillofacial region affected by HO determines the degree of limitations of the maximum mouth opening. This finding may be important for establishing clinical guidelines for the dental management of FOP patients., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Schoenmaker, Dahou Bouchankouk, Özkan, Gilijamse, Bouvy-Berends, Netelenbos, Lobbezoo, Eekhoff and de Vries.)

We aimed to develop a disease-specific adrenocortical carcinoma (ACC) health-related quality of life (HRQoL) questionnaire (ACC-QOL) and assess HRQoL in a population-based cohort of patients with ACC. Development was in line with European Organization for Research and Treatment of Cancer (EORTC) guidelines, though not an EORTC product. In phase I and II, we identified 90 potential HRQoL issues using literature and focus groups, which were reduced to 39 by healthcare professionals. Pilot testing resulted in 28 questions, to be used alongside the EORTC QLQ-C30. In Phase III, 100 patients with ACC were asked to complete the questionnaires twice in the PROFILES registry (3-month interval, respondents: first 67, second 51). Confirmatory factor analysis demonstrated the structural validity of 26 questions with their scale structure (mitotane side-effects, hypercortisolism/hydrocortisone effects, emotional effects). Internal consistency and reliability were good (Cronbach's alpha 0.897, Interclass correlation coefficient 0.860). Responsiveness analysis showed good discriminative ability (AUC 0.788). Patients diagnosed more than 5 years ago reported a good HRQoL compared with the Dutch reference population, but experienced residual fatigue and emotional problems. Patients who underwent recent treatment reported a lower HRQoL and problems in several domains. In conclusion, we developed an ACC-specific HRQoL questionnaire with good psychometric properties.

In this issue, we outline the developments that have increasingly enabled people with insulin-dependent diabetes to professionally operate a vehicle. We focus on all professions in passenger transport in the Netherlands, with the pilot as a reference. A protocol has been developed in the UK to enable safe and responsible flying by selected pilots with type 1 diabetes mellitus and insulin dependent type 2 diabetes mellitus. It is used in several countries within and outside Europe, but not yet in the Netherlands. Modern diabetes care, innovative monitoring, good medical supervision and support ensure that patients with insulin-dependent diabetes in the Netherlands can work under certain circumstances as train, ship, tram, metro and bus transporters, but not as a pilot. Based on sufficient data and good arguments, introducing the ''pilot-diabetes'' protocol in the Netherlands would be a good and responsible step forward.

Purpose: Osteogenesis imperfecta (OI) is a rare inherited heterogeneous connective tissue disorder characterized by bone fragility, low bone mineral density, skeletal deformity and blue sclera. The dominantly inherited forms of OI are predominantly caused by mutations in either the COL1A1 or COL1A2 gene. Collagen type I is one of the major structural proteins of the eyes and therefore is the eye theoretically prone to alterations in OI. The aim of this systematic review was to provide an overview of the known ocular problems reported in OI., Methods: A literature search (in PubMed, Embase and Scopus), which included articles from inception to August 2020, was performed in accordance with the PRISMA guidelines., Results: The results of this current review show that almost every component of the eye could be affected in OI. Decreased thickness of the cornea and sclera is an important factor causing eye problems in patients with OI such as blue sclera. Findings that stand out are ruptures, lacerations and other eye problems that occur after minor trauma, as well as complications from standard surgical procedures., Discussion: Alterations in collagen type I affect multiple structural components of the eye. It is recommended that OI patients wear protective glasses against accidental eye trauma. Furthermore, when surgery is required, it should be approached with caution. The prevalence of eye problems in different types of OI is still unknown. Additional research is required to obtain a better understanding of the ocular defects that may occur in OI patients and the underlying pathology., (© 2021 The Authors. Acta Ophthalmologica published by John Wiley & Sons Ltd on behalf of Acta Ophthalmologica Scandinavica Foundation.)

Introduction: Respiratory failure is a major cause of death in patients with Osteogenesis Imperfecta. Moreover, respiratory symptoms seem to have a dramatic impact on their quality of life. It has long been thought that lung function disorders in OI are mainly due to changes in the thoracic wall, caused by bone deformities. However, recent studies indicate that alterations in the lung itself can also undermine respiratory health., Objectives: Is there any intrapulmonary alteration in Osteogenesis Imperfecta that can explain decreased pulmonary function? The aim of this systematic literature review is to investigate to what extent intrapulmonary or extrapulmonary thoracic changes contribute to respiratory dysfunction in Osteogenesis Imperfecta., Methods: A literature search (in PubMed, Embase, Web of Science, and Cochrane), which included articles from inception to December 2020, was performed in accordance with the PRISMA guidelines., Results: Pulmonary function disorders have been described in many studies as secondary to scoliosis or to thoracic skeletal deformities. The findings of this systematic review suggest that reduced pulmonary function can also be caused by a primary pulmonary problem due to intrinsic collagen alterations., Conclusions: Based on the most recent studies, the review indicates that pulmonary defects may be a consequence of abnormal collagen type I distorting the intrapulmonary structure of the lung. Lung function deteriorates further when intrapulmonary defects are combined with severe thoracic abnormalities. This systematic review reveals novel findings of the underlying pathological mechanism which have clinical and diagnostic implications for the assessment and treatment of pulmonary function disorders in Osteogenesis Imperfecta.KEY MESSAGESDecreased pulmonary function in Osteogenesis Imperfecta can be attributed to primary pulmonary defects due to intrapulmonary collagen alterations and not solely to secondary problems arising from thoracic skeletal dysplasia.Type I collagen defects play a crucial role in the development of the lung parenchyma and defects, therefore, affect pulmonary function. More awareness is needed among physicians about pulmonary complications in Osteogenesis Imperfecta to develop novel concepts on clinical and diagnostic assessment of pulmonary functional disorders.