The Design, Development, and Usability Testing of an eHealth Program for Youths With Osteogenesis Imperfecta: Protocol for a 2-Phase User-Centered Mixed Methods Study.

BACKGROUND: Innovative approaches are needed to address the self-management needs of youths with osteogenesis imperfecta (OI) transitioning into adult-oriented health care systems. Using a sequentially phased research approach, the goal is to design, develop, and test the usability of an innovative eHealth program called "Teens Taking Charge: Managing OI Online," hereafter named "Teens OI." This program seeks to optimize self-management, facilitate a successful transition to adult care, and address a critical gap in the quality of care for youths with OI. OBJECTIVE: The study objectives are to (1) design and develop an English and French version of the Teens OI and (2) test the usability of the Teens OI in terms of efficiency, effectiveness, and satisfaction from the perspectives of youths with OI and their parents. METHODS: A user-centered design is presently in progress to design and develop Teens OI. A "Website Design and Development Council" (ie, Council) has been convened, with 20 youths and parent dyads recruited and global experts surveyed at an international meeting. With unanimous support from the Council, usability testing of the Teens OI will ensue in 4 iterative cycles with 32 youth-parent dyads. All sociodemographic and usability metrics will be descriptively analyzed. All recorded interview and focus group data are analyzed using content analysis techniques involving an iterative process of data reduction, data display, conclusion drawing, and verification. RESULTS: As of December 2022, an 8-person, interdisciplinary Teens OI council, comprising 4 health care professionals, 3 youths and young adults with OI, and 1 parent, has been convened to oversee the design and development of Teens OI. Two cycles of interviews have been conducted with 10 youths with OI with or without their parents (n=6) from December 2021 to September 2022. Data analysis has been in progress since April 2022. Aim 2 is ethically approved and will commence following the completion of content development, expected by late July 2023. Preliminary analysis indicates that the following topics need to be prioritized for the youths: mental health, pain, accessibility, medical care, education, community, and parental care. CONCLUSIONS: The proposed study will design and develop a self-management and transitional care program for youths with OI in partnership with patients, caregivers, and health care professionals. This study leverages youths' openness to adopt eHealth technologies to meet their needs and has the potential to actively engage them to autonomously manage their lifelong conditions, and facilitate a successful transition to adult health care. Finally, the proposed study will also address a critical gap in the quality of care and the growing concern that the OI population transitioning from pediatric to adult care is at risk of various adverse events associated with the transition. INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID): DERR1-10.2196/47524.

Update on trabecular bone score.

Trabecular bone score (TBS) is an indirect and noninvasive measure of bone quality. A low TBS indicates degraded bone microarchitecture, predicts osteoporotic fracture, and is partially independent of clinical risk factors and bone mineral density (BMD). There is substantial evidence supporting the use of TBS to assess vertebral, hip, and major osteoporotic fracture risk in postmenopausal women, as well as to assess hip and major osteoporotic fracture risk in men aged > 50 years. TBS complements BMD information and can be used to adjust the FRAX (Fracture Risk Assessment) score to improve risk stratification. While TBS should not be used to monitor antiresorptive therapy, it may be potentially useful for monitoring anabolic therapy. There is also a growing body of evidence indicating that TBS is particularly useful as an adjunct to BMD for fracture risk assessment in conditions associated with increased fracture risk, such as type-2 diabetes, chronic corticosteroid excess, and other conditions wherein BMD readings are often misleading. The interference of abdominal soft tissue thickness (STT) on TBS should also be considered when interpreting these findings because image noise can impact TBS evaluation. A new TBS software version based on an algorithm that accounts for STT rather than BMI seems to correct this technical limitation and is under development. In this paper, we review the current state of TBS, its technical aspects, and its evolving role in the assessment and management of several clinical conditions.

Update on trabecular bone score

ABSTRACT Trabecular bone score (TBS) is an indirect and noninvasive measure of bone quality. A low TBS indicates degraded bone microarchitecture, predicts osteoporotic fracture, and is partially independent of clinical risk factors and bone mineral density (BMD). There is substantial evidence supporting the use of TBS to assess vertebral, hip, and major osteoporotic fracture risk in postmenopausal women, as well as to assess hip and major osteoporotic fracture risk in men aged > 50 years. TBS complements BMD information and can be used to adjust the FRAX (Fracture Risk Assessment) score to improve risk stratification. While TBS should not be used to monitor antiresorptive therapy, it may be potentially useful for monitoring anabolic therapy. There is also a growing body of evidence indicating that TBS is particularly useful as an adjunct to BMD for fracture risk assessment in conditions associated with increased fracture risk, such as type-2 diabetes, chronic corticosteroid excess, and other conditions wherein BMD readings are often misleading. The interference of abdominal soft tissue thickness (STT) on TBS should also be considered when interpreting these findings because image noise can impact TBS evaluation. A new TBS software version based on an algorithm that accounts for STT rather than BMI seems to correct this technical limitation and is under development. In this paper, we review the current state of TBS, its technical aspects, and its evolving role in the assessment and management of several clinical conditions.

Effect of soft tissue noise on trabecular bone score in postmenopausal women with diabetes: A cross sectional study.

BACKGROUND: Type 2 diabetes (T2D) is associated with increased fracture risk, despite similar or greater BMD compared to nondiabetics. TBS predicts fracture risk in T2D and nondiabetics. However, increased abdominal thickness, a common feature in T2D, may reduce TBS values. AIM: To study the relationship among glycemic status, BMD and TBS, considering abdominal soft tissue thickness (STT) interference. METHODS: Cross-sectional analysis of 493 women ≥65 years, with simultaneous DXA scans and HbA1c measures. STT and TBS (iNsight Software, v3.0) were derived from lumbar spine (LS) scans. Subjects were divided according to HbA1c levels: 1 (≥6.5%; n = 116), 2 (5.7-6.4%; n = 217) and 3 (≤5.6%; n = 160). Group 1 was further divided based on HbA1c and/or disease duration: 1a (HbA1c ≥ 7.5%; n = 42), 1b (HbA1c ≥ 6.5% and disease duration ≥5 years; n = 63) and 1c (HbA1c ≥ 7.5% and disease duration ≥5 years; n = 30). FINDINGS: For the entire cohort, mean age, TBS, BMI and STT were 71.8 ± 6.0 years, 1.299 ± 0.101, 26.9 ± 4.1 kg/m2, and 21.4 ± 2.9 cm, respectively. LS-BMD was similar among groups. BMD in hip sites and STT were higher in group 1. TBS was lower in patients with higher HbA1c (P = 0.020), with a mean TBS in groups 1, 2, and 3 of 1.280, 1.299 and 1.314, respectively. This difference remained after adjusting for age, LS-BMD and BMI (P = 0.010). After replacing BMI with STT, TBS differences were no longer significant (P = 0.270). The same was observed when subgroups 1a and 1b were compared to group 3. However, for subgroup 1c, TBS remained lower compared to group 3, even after adjusting for age, LS-BMD and STT, with a borderline P-value (1.275 vs. 1.308; P = 0.047). CONCLUSION: Higher HbA1c levels were associated with greater BMD in hip sites, higher abdominal STT and lower TBS values. However, after including the STT in the adjustment, TBS differences among groups disappeared, except in women with higher HbA1c levels and longer disease duration.

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

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

Osteogenesis Imperfecta: Skeletal Outcomes After Bisphosphonate Discontinuation at Final Height.

Intravenous cyclical bisphosphonates are widely used to treat children with moderate to severe osteogenesis imperfecta (OI). Bisphosphonates are often discontinued when growth is completed, but subsequent skeletal changes have not been studied in detail. We assessed 31 patients (22 females) with OI who had started intravenous bisphosphonates (either pamidronate or zoledronic acid) before 13 years of age, were treated for at least 2 years (range 4.7-15.7 years), and discontinued treatment after completion of growth, when their age ranged from 13.4 to 20.0 years (mean 16.4 years). At 4 years after treatment discontinuation, lumbar spine areal bone mineral density (BMD) had increased by 4% (p < 0.05). Peripheral quantitative computed tomography of the radius showed a decrease in trabecular volumetric BMD at the distal metaphysis of 19% but an increase in cortical volumetric BMD of 4% (p < 0.05 for both). None of the patients sustained a new vertebral compression fracture during follow-up. The proportion of patients with new long-bone fractures was higher in the 2 years before treatment discontinuation than in the last 2 years of follow-up (42% and 16%, respectively; p < 0.05). © 2019 American Society for Bone and Mineral Research.

Pain experiences of adults with osteogenesis imperfecta: An integrative review.

Background: Pain is a common symptom of osteogenesis imperfecta (OI) among children and adolescents. However, little is currently known of the pain experiences of adults with OI. Aims: The aims of this study were to critically appraise the studies assessing OI pain, to synthesize the pain experiences of adults with OI, and to compare the adult OI pain experiences to childhood. Methods: An integrative review was conducted. Five electronic bibliographic databases were searched. Published quantitative, qualitative, and/or mixed-method studies assessing pain in adults with OI were screened, reviewed, and appraised. Descriptive statistics were used to calculate quality scores, summarize sample characteristics, and synthesize findings. Extracted pain data were analyzed using constant comparison and consolidated into meaningful themes. Results: From the 832 titles identified, 14 studies including seven case reports met the inclusion criteria. Study appraisal scores ranged from low to moderate using the Quality Assessment Tool and the Case Report Checklist. The majority of studies assessed pain as a secondary outcome (71.4%) using well-established tools (64.2%). Adults with OI experience pain of mild to moderate intensity, which may interfere with completion of daily activities. Two themes emerged from analysis of the data: mild chronic pain persists despite surgical, pharmacological, or nonpharmacological interventions and past fractures and structural deformities may trigger onset of chronic pain in adulthood. Conclusion: Limited attention has been given to exploring the pain experience of adults diagnosed with OI. Pain is a long-term symptom of OI requiring further in-depth investigation to better understand and manage pain in adults with OI.

Contexte: La douleur est un symptôme commun de l'ostéogenèse imparfaite (OI) chez les enfants et les adolescents. Toutefois, on sait actuellement peu de choses au sujet de la douleur ressentie par les adultes atteints d'OI.But: Effectuer une appréciation critique des études évaluant la douleur occasionnée par l'OI, faire la synthèse de l'information sur la douleur ressentie par les adultes atteints d'OI et comparer la douleur ressentie à l'âge adulte à celle ressentie pendant l'enfance.Méthodes: Un examen par intégration a été mené. Des recherches ont été effectuées dans cinq bases de données bibliographiques électroniques. Les études quantitatives, qualitatives ou mixtes publiées qui évaluaient la douleur chez les adultes atteints d'OI ont été sélectionnées, examinées et évaluées. Des statistiques descriptives ont été utilisées pour calculer leur score de qualité, résumer les caractéristiques de leur échantillon et synthétiser leurs conclusions. Les données sur la douleur qui avaient été extraites ont été analysées à l'aide de la méthode de la comparaison constante et regroupées en thèmes significatifs.Résultats: Parmi les 832 titres recensés, 14 études comprenant sept rapports de cas répondaient aux critères d'inclusion. Au moment de les évaluer, les études ont obtenu un score de qualité allant de faible à modéré en utilisant l'Outil d'évaluation de la qualité et la Liste de vérification pour les études de cas. La majorité des études évaluaient la douleur en tant que résultat secondaire (71,4 %) à l'aide d'outils bien établis (64,2 %). Les adultes attents d'OI ressentent une douleur d'une intensité allant de légère à modérée, qui peut perturber leurs activités quotidiennes. Deux thèmes ont émergé de l'analyse des données : « La douleur chronique légère persiste malgré les inerventions chirurgicales, pharmacologiques ou non phramacologiques ¼ et « les fractures passées et les malformations structurelles peuvent déclencher la douleur chronique à l'âge adulte ¼.Conclusion: L'étude de la douleur ressentie par les adultes ayant reçu un diagnostic d'OI n'a reçu qu'une attention limitée. La douleur est un symptôme d'OI à long terme qui nécessite une investigation plus approfondie afin de mieux la comprendre et d'en assurer une meilleure prise en charge chez les adultes atteints d'OI.

Osteogenesis imperfecta: diagnosis and treatment.

PURPOSE OF REVIEW: Here we summarize the diagnosis of osteogenesis imperfecta, discuss newly discovered genes involved in osteogenesis imperfecta, and review the management of this disease in children and adults. RECENT FINDINGS: Mutations in the two genes coding for collagen type I, COL1A1 and COL1A2, are the most common cause of osteogenesis imperfecta. In the past 10 years, defects in at least 17 other genes have been identified as responsible for osteogenesis imperfecta phenotypes, with either dominant or recessive transmission. Intravenous bisphosphonate infusions are the most widely used medical treatment. This has a marked effect on vertebra in growing children and can lead to vertebral reshaping after compression fractures. However, bisphosphonates are less effective for preventing long-bone fractures. At the moment, new therapies are under investigation. SUMMARY: Despite advances in the diagnosis and treatment of osteogenesis imperfecta, more research is needed. Bisphosphonate treatment decreases long-bone fracture rates, but such fractures are still frequent. New antiresorptive and anabolic agents are being investigated but efficacy and safety of these drugs, especially in children, need to be better established before they can be used in clinical practice.

The psychosocial experience of individuals living with osteogenesis imperfecta: a mixed-methods systematic review.

PURPOSE: Osteogenesis imperfecta (OI) is a genetic disorder (prevalence: 1:10,000), leading to bone fragility, frequent fractures, and varying degrees of physical limitations. Despite a substantial amount of research on the genetics, pathophysiology, and treatments related to OI, there remains a paucity of knowledge concerning the lived psychosocial experience of the OI population. This mixed-methods systematic review aimed to review, appraise, and synthesize the literature on the psychosocial experience of children and adults with OI with the goal of identifying implications for research, practice, and policy-making. METHODS: Using a systematic methodology, quantitative, qualitative, and mixed-methods studies were accessed through database searching, screened, assessed for eligibility, and appraised. Data from the selected studies fulfilling the eligibility and quality criteria were extracted and synthesized using thematic analysis with an inductive approach. RESULTS: A total of four qualitative and 20 quantitative studies, with various study designs and methodologies ranging in quality, were included in the review (n = 800; comprising 610 children and 175 adults with OI types I, III, IV, and V, ten parents and five healthcare professionals). Six themes were identified: intellectual feats, isolation and feeling different, fear of fractures, coping with challenges, adapting by learning new skills, and social relationships. CONCLUSION: These findings highlighted key aspects of the experiences of children and adults with OI and will be essential for improving the quality and direction of research, tailoring clinical interventions addressing the psychosocial needs and quality of life of individuals with OI, and raising awareness among caregivers, healthcare professionals, administrators, and policy-makers associated with the OI population.

Involving Families with Osteogenesis Imperfecta in Health Service Research: Joint Development of the OI/ECE Questionnaire.

BACKGROUND: Despite the growing interest in understanding the psycho-social impact of rare genetic diseases, few studies examine this concept and even fewer seek to obtain feedback from families who have lived the experience. The aim of this project was to involve families of children living with osteogenesis imperfecta (OI) in the development of a tool to assess the impact of OI on the lives of patients and their families. METHODS: This project used an integrated knowledge translation approach in which knowledge users (clinicians and people living with OI and their families) were consulted throughout the four steps of development, that is: content mapping, item generation, tool appraisal and pre-testing of the questionnaires. The International Classification of Functioning and Health was used as a framework for content mapping. Based on a scoping review we selected two validated tools to use as a basis for developing the questionnaire. The final parent self-report version measured six domains: experience of diagnosis; use of health services; use of social and psychological support services; expectations about tertiary specialized centers; and socio-demographic information. RESULTS: A total of 27 out of 40 families receiving care at the Shriners Hospital for Children-Canada and invited to participate in the pre-test returned the completed questionnaires. In more than two-thirds of families (69%; n = 18) OI was suspected either at or within the first 3 months after birth. Up to 46% of families consulted between 3 and 5 doctors (46%; n = 12) prior to final diagnosis. The use of services by families varied from 0 to 16 consultations, 0 to 9 exploratory examinations and 1 to 10 types of allied health services. In the 12 months prior to the study, fewer than a quarter of children had been admitted, for treatment, for hospital stays of longer than 8 hours or to an emergency department (24% and 9% respectively). Only 29% of parents received psychological support. CONCLUSION: This joint development process generated a tool, with good psychometric properties, that provides unique insight into the experiences of patients and families with OI, the psycho-social impact of the illness, and their service needs and expectations.

Body Composition in Children and Adolescents with Osteogenesis Imperfecta.

OBJECTIVE: To use peripheral quantitative computed tomography to determine the cross-sectional area (CSA) of subcutaneous fat and muscle (fat CSA, muscle CSA) in transverse forearm scans in patients with osteogenesis imperfecta (OI). STUDY DESIGN: Fat and muscle CSA were quantified in 266 individuals (142 female) aged 5-20 years who had a diagnosis of OI type I, III, or IV and who had mutations in COL1A1 or COL1A2. Results were compared with those of 255 healthy controls. RESULTS: In a subgroup of 39 patients with OI type I, % fat CSA correlated closely with total body percentage fat mass as determined by dual-energy x-ray absorptiometry (R(2) = 0.69; P < .001). In the entire study cohort, muscle CSA adjusted for age, sex, and forearm length was lower in OI type I and III than in controls (P < .05 each), but fat CSA was similar between OI types and controls. No relationship between the type of disease-causing mutation in the COL1A1 or COL1A2 genes and fat CSA or muscle CSA was found. CONCLUSIONS: Children and adolescents with OI have low muscle size but a normal amount of subcutaneous fat at the forearm.

Evaluation of a Modified Pamidronate Protocol for the Treatment of Osteogenesis Imperfecta.

Intravenous pamidronate is widely used to treat children with osteogenesis imperfecta (OI). In a well-studied protocol ('standard protocol'), pamidronate is given at a daily dose of 1 mg per kg body weight over 4 h on 3 successive days; infusion cycles are repeated every 4 months. Here, we evaluated renal safety of a simpler protocol for intravenous pamidronate infusions (2 mg per kg body weight given in a single infusion over 2 h, repeated every 4 months; 'modified protocol'). Results of 18 patients with OI types I, III, or IV treated with the modified protocol for 12 months were compared to 18 historic controls, treated with standard protocol. In the modified protocol, mild transient post-infusion increases in serum creatinine were found during each infusion but after 12 months serum creatinine remained similar from baseline [0.40 mg/dl (SD: 0.13)] to the end of the study [0.41 mg/dl (SD: 0.11)] (P = 0.79). The two protocols led to similar changes in serum creatinine during the first pamidronate infusion [modified protocol: +2% (SD: 21%); standard protocol: -3% (SD: 8%); P = 0.32]. Areal lumbar spine bone mineral density Z-scores increased from -2.7 (SD: 1.5) to -1.8 (SD: 1.4) with the modified protocol, and from -4.1 (SD: 1.4) to -3.1 (SD: 1.1) with standard protocol (P = 0.68 for group differences in bone density Z-score changes). The modified pamidronate protocol is safe and may have similar effects on bone density as the standard pamidronate protocol. More studies are needed with longer follow-up to prove anti-fracture efficacy.

Osteogenesis Imperfecta Type I Caused by COL1A1 Deletions.

Osteogenesis imperfecta (OI) type I is usually caused by COL1A1 stop or frameshift mutations, leading to COL1A1 haploinsufficiency. Here we report on 12 individuals from 5 families who had OI type I due to an unusual cause­heterozygous deletions of the entire COL1A1 gene. The deletions were initially detected by semiconductor-based sequencing of genomic DNA and confirmed by quantitative PCR. Array comparative genomic hybridization in DNA of the index patient in each family showed that deletion size varied from 18.5 kb to 2.23 Mb between families, encompassing between 1 and 47 genes (COL1A1 included). The skeletal phenotype of the affected individuals was similar to that of patients with haploinsufficiency caused by COL1A1 stop or frameshift mutations. However, one individual with a deletion that included also DLX3 and DLX4 had tooth discoloration and bone fragility. Three individuals from 2 families had deletions that included also CACNA1G, and these individuals had learning disabilities. These features are not usually observed in COL1A1 haploinsufficiency, but are in accordance with previously described individuals in whom deletions included the same genes. In summary, we found deletions of COL1A1 in 5 out of 161 families (3 %) with OI type I that were evaluated. Deletions encompassing not only COL1A1 but also neighboring genes can lead to contiguous gene syndromes that may include dental involvement and learning disability.

Multidisciplinary Treatment of Severe Osteogenesis Imperfecta: Functional Outcomes at Skeletal Maturity.

OBJECTIVE: To determine the functional outcomes associated with long-term multidisciplinary treatment, intravenous bisphosphonate treatment, orthopedic surgery, and rehabilitation in children with severe osteogenesis imperfecta (OI) (diagnosed clinically as OI types III or IV). DESIGN: Retrospective study where outcomes were measured prospectively. SETTING: Pediatric orthopedic hospital. PARTICIPANTS: Adolescents (N=41; age range, 15-21y) with severe OI (OI type III: n=17; OI type IV: n=24) who had started therapy before the age of 6 years, had received treatment for at least 10 years, and had achieved final height. INTERVENTIONS: Intravenous bisphosphonate treatment, orthopedic surgery, and rehabilitation. MAIN OUTCOME MEASURE: Pediatric Evaluation of Disability Inventory. RESULTS: At the time of the last available follow-up examination, none of the individuals diagnosed with OI type III (most severely affected group) was able to ambulate without ambulation aids, whereas 20 (83%) patients with OI type IV were able to ambulate without ambulation aids. Regarding self-care, we specifically assessed 8 skills that we deemed essential for living independently (grooming; dressing; toileting; bed, chair, toilet, tub, and car transfers). Only 6 (35%) of the youths with OI type III were able to complete all 8 items, whereas 23 (96%) individuals with OI type IV managed to perform all tasks. Teens with OI type III often needed assistance for the transfer to toilet, tub, and car and for personal hygiene and clothing management associated with toileting, usually because of limitations in upper-extremity function. CONCLUSIONS: These observations suggest that further improvements in the functional status of the most severely affected children with OI are contingent on advances in the clinical management of upper-extremity issues.

Intravenous Bisphosphonate Therapy of Young Children With Osteogenesis Imperfecta: Skeletal Findings During Follow Up Throughout the Growing Years.

Cyclical intravenous bisphosphonate therapy is widely used to treat children with osteogenesis imperfecta (OI), but little is known about long-term treatment outcomes. We therefore reviewed 37 children with OI (OI type I, n = 1; OI type III, n = 14; and OI type IV, n = 22) who started intravenous bisphosphonate therapy before 5 years of age (median 2.2 years; range, 0.1 to 4.8 years), and who had a subsequent follow-up period of at least 10 years (median 14.8 years; range, 10.7 to 18.2 years), during which they had received intravenous bisphosphonate treatment (pamidronate or zoledronic acid) for at least 6 years. During the observation period, the mean lumbar spine areal bone mineral density Z-score increased from -6.6 (SD 3.1) to -3.0 (SD 1.8), and weight Z-score increased from -2.3 (SD 1.5) to -1.7 (SD 1.7) (p < 0.001 and p = 0.008). At the time of the last assessment, patients with OI type IV had significantly higher height Z-scores than a control group of patients matched for age, gender, and OI type who had not received bisphosphonates. Patients had a median of six femur fractures (range, 0 to 18) and five tibia fractures (range, 0 to 17) during the follow-up period. At baseline, 35% of vertebra were affected by compression fractures, whereas only 6% of vertebra appeared compressed at the last evaluation (p < 0.001), indicating vertebral reshaping during growth. Spinal fusion surgery was performed in 16 patients (43%). Among the 21 patients who did not have spinal fusion surgery, 13 had scoliosis with a curvature ranging from 10 to 56 degrees. In conclusion, long-term intravenous bisphosphonate therapy was associated with higher Z-scores for lumbar spine areal bone mineral density and vertebral reshaping, but long-bone fracture rates were still high and the majority of patients developed scoliosis.

Recessive osteogenesis imperfecta caused by missense mutations in SPARC.

Secreted protein, acidic, cysteine-rich (SPARC) is a glycoprotein that binds to collagen type I and other proteins in the extracellular matrix. Using whole-exome sequencing to identify the molecular defect in two unrelated girls with severe bone fragility and a clinical diagnosis of osteogenesis imperfecta type IV, we identified two homozygous variants in SPARC (GenBank: NM_003118.3; c.497G>A [p.Arg166His] in individual 1; c.787G>A [p.Glu263Lys] in individual 2). Published modeling and site-directed mutagenesis studies had previously shown that the residues substituted by these mutations form an intramolecular salt bridge in SPARC and are essential for the binding of SPARC to collagen type I. The amount of SPARC secreted by skin fibroblasts was reduced in individual 1 but appeared normal in individual 2. The migration of collagen type I alpha chains produced by these fibroblasts was mildly delayed on SDS-PAGE gel, suggesting some overmodification of collagen during triple helical formation. Pulse-chase experiments showed that collagen type I secretion was mildly delayed in skin fibroblasts from both individuals. Analysis of an iliac bone sample from individual 2 showed that trabecular bone was hypermineralized on the material level. In conclusion, these observations show that homozygous mutations in SPARC can give rise to severe bone fragility in humans.

The effect of SERPINF1 in-frame mutations in osteogenesis imperfecta type VI.

Osteogenesis imperfecta type VI is caused by mutations in SERPINF1, which codes for pigment-epithelium derived factor (PEDF). Most of the reported SERPINF1 mutations lead to premature termination codons, but three in-frame insertion or deletion mutations have also been reported. It is not clear how such in-frame mutations lead to OI type VI. In the present study we therefore investigated how SERPINF1 in-frame mutations affect the intracellular localization and secretion of PEDF. Skin fibroblasts affected by SERPINF1 in-frame mutations transcribed SERPINF1 at slightly reduced levels but secretion of PEDF was markedly diminished. Two deletions (p.F277del and the deletion of SERPINF1 exon 5) were associated with retention of PEDF in the endoplasmic reticulum and a stress response in osteoblastic cells. A recurrent in-frame duplication of three amino acids (p.Ala91_Ser93dup) appeared to lead to intracellular degradation but no retention in the endoplasmic reticulum or stress response. Immunofluorescence imaging in transiently transfected osteoblastic MC3T3-E1 cells suggested that PEDF affected by in-frame mutations was not transported along the secretory pathway. MC3T3-E1 osteoblasts stably overexpressing SERPINF1 with the p.Ala91_Ser93dup mutation had decreased collagen type I deposition and mineralization. Thus, the assessed homozygous in-frame deletions or insertions lead to retention or degradation within cellular compartments and thereby interfere with PEDF secretion.

A polyadenylation site variant causes transcript-specific BMP1 deficiency and frequent fractures in children.

We had previously published the clinical characteristics of a bone fragility disorder in children that was characterized mainly by lower extremity fractures and a mineralization defect in bone tissue but not on the growth plate level. We have now performed whole-exome sequencing on four unrelated individuals with this phenotype. Three individuals were homozygous for a nucleotide change in BMP1, affecting the polyadenylation signal of the transcript that codes for the short isoform of BMP1 (BMP1-1) (c.*241T>C). In skin fibroblasts of these individuals, we found low levels of BMP1-1 transcript and protein. The fourth individual was compound heterozygous for the c.*241T>C variant in BMP1-1 and a variant in BMP1 exon 15 (c.2107G>C) that affected splicing in both BMP1-1 and the long isoform of BMP1 (BMP1-3). Both the homozygous 3'UTR variant and the compound heterozygous variants were associated with impaired procollagen type I C-propeptide cleavage, as the amount of free C-propeptide in the supernatant of skin fibroblasts was less than in controls. Peripheral quantitative computed tomography showed that all individuals had elevated volumetric cortical bone mineral density. Assessment of iliac bone samples by histomorphometry and quantitative backscattered electron imaging indicated that the onset of mineralization at bone formation sites was delayed, but that mineralized matrix was hypermineralized. These results show that isolated lack of BMP1-1 causes bone fragility in children.

Normal bone density and fat mass in heterozygous SERPINF1 mutation carriers.

CONTEXT: Homozygous mutations in SERPINF1 cause deficiency of pigment epithelium-derived factor (PEDF) and lead to osteogenesis imperfecta (OI) type VI, but it is not known whether heterozygous mutations in SERPINF1 cause a phenotype. OBJECTIVE: In the present study, we therefore assessed family members of individuals with OI type VI and compared the results of SERPINF1 mutation carriers with those of noncarriers of SERPINF1 mutations. SETTING: This study was conducted at a metabolic bone clinic of a pediatric orthopedic hospital. SUBJECTS: The study population comprised 29 family members (age range 8-89 y; 18 females, 11 males) of patients with a diagnosis of OI type VI. Eighteen individuals were heterozygous for SERPINF1 mutations, but the others did not carry a mutation. MAIN OUTCOME MEASURES: PEDF expression was assessed in skin fibroblasts from four heterozygous SERPINF1 mutation carriers. Skeletal characteristics and body composition were measured using dual-energy X-ray absorptiometry and peripheral quantitative computed tomography. Serum samples were used to quantify markers of bone metabolism, lipid status, and PEDF. RESULTS: Carriers of heterozygous stop or frame shift mutations in SERPINF1 had low SERPINF1 transcript levels. Mean PEDF serum concentrations were significantly lower in the carrier group than in the noncarriers (P = .04). However, no group differences were found with regard to areal bone density at the lumbar spine and total body, volumetric bone density at the radius and tibia, body composition, lipid status, and markers of bone metabolism. CONCLUSION: Heterozygous SERPINF1 mutation carriers had no detectable abnormalities in fat and bone, despite decreased PEDF expression.