Characterization and functional analysis of the adipose tissue-derived stromal vascular fraction of pediatric patients with osteogenesis imperfecta.

Pediatric patients with Osteogenesis Imperfecta (OI), a heritable connective tissue disorder, frequently suffer from long bone deformations. Surgical correction often results in bone non-unions, necessitating revision surgery with autogenous bone grafting using bone-marrow-derived stem cells (BM-SC) to regenerate bone. BM-SC harvest is generally invasive and limited in supply; thus, adipose tissue's stromal vascular fraction (SVF) has been introduced as an alternative stem cell reservoir. To elucidate if OI patients' surgical site dissected adipose tissue could be used as autologous bone graft in future, we investigated whether the underlying genetic condition alters SVF's cell populations and in vitro differentiation capacity. After optimizing SVF isolation, we demonstrate successful isolation of SVF of pediatric OI patients and non-OI controls. The number of viable cells was comparable between OI and controls, with about 450,000 per gram tissue. Age, sex, type of OI, disease-causing collagen mutation, or anatomical site of harvest did not affect cell outcome. Further, SVF-containing cell populations were similar between OI and controls, and all isolated SVF's demonstrated chondrogenic, adipogenic, and osteogenic differentiation capacity in vitro. These results indicate that SVF from pediatric OI patients could be used as a source of stem cells for autologous stem cell therapy in OI.

Calvaria Bone Transcriptome in Mouse Models of Osteogenesis Imperfecta.

Osteogenesis imperfecta (OI) is a bone fragility disorder that is usually caused by mutations affecting collagen type I. We compared the calvaria bone tissue transcriptome of male 10-week-old heterozygous Jrt (Col1a1 mutation) and homozygous oim mice (Col1a2 mutation) to their respective littermate results. We found that Jrt and oim mice shared 185 differentially expressed genes (upregulated: 106 genes; downregulated: 79 genes). A total of seven genes were upregulated by a factor of two or more in both mouse models (Cyp2e1, Slc13a5, Cgref1, Smpd3, Ifitm5, Cthrc1 and Rerg). One gene (Gypa, coding for a blood group antigen) was downregulated by a factor of two or more in both OI mouse models. Overrepresentation analyses revealed that genes involved in 'ossification' were significantly overrepresented among upregulated genes in both Jrt and oim mice, whereas hematopoietic genes were downregulated. Several genes involved in Wnt signaling and transforming growth factor beta signaling were upregulated in oim mice, but less so in Jrt mice. Thus, this study identified a set of genes that are dysregulated across various OI mouse models and are likely to play an important role in the pathophysiology of this disorder.

Localized chondro-ossification underlies joint dysfunction and motor deficits in the Fkbp10 mouse model of osteogenesis imperfecta.

Osteogenesis imperfecta (OI) is a genetic disorder that features wide-ranging defects in both skeletal and nonskeletal tissues. Previously, we and others reported that loss-of-function mutations in FK506 Binding Protein 10 (FKBP10) lead to skeletal deformities in conjunction with joint contractures. However, the pathogenic mechanisms underlying joint dysfunction in OI are poorly understood. In this study, we have generated a mouse model in which Fkbp10 is conditionally deleted in tendons and ligaments. Fkbp10 removal substantially reduced telopeptide lysyl hydroxylation of type I procollagen and collagen cross-linking in tendons. These biochemical alterations resulting from Fkbp10 ablation were associated with a site-specific induction of fibrosis, inflammation, and ectopic chondrogenesis followed by joint deformities in postnatal mice. We found that the ectopic chondrogenesis coincided with enhanced Gli1 expression, indicating dysregulated Hedgehog (Hh) signaling. Importantly, genetic inhibition of the Hh pathway attenuated ectopic chondrogenesis and joint deformities in Fkbp10 mutants. Furthermore, Hh inhibition restored alterations in gait parameters caused by Fkbp10 loss. Taken together, we identified a previously unappreciated role of Fkbp10 in tendons and ligaments and pathogenic mechanisms driving OI joint dysfunction.

Biological basis of child health 6: development of the skeletal system and orthopaedic conditions.

This article is the sixth in a series on the biological basis of child health. It provides an overview of the development of the skeletal system before and after birth, and outlines the potential congenital anomalies that may occur. The article explains the structure and function of the bones before describing the role of the joints, tendons and ligaments. It also outlines the presentation and management of some of the common orthopaedic conditions seen in infants and children, including fractures, osteogenesis imperfecta, scoliosis, juvenile idiopathic arthritis, developmental dysplasia of the hip and achondroplasia.

Monthly intravenous alendronate treatment can maintain bone strength in osteogenesis imperfecta patients following cyclical pamidronate treatment.

Objectives Osteogenesis imperfecta (OI) is a skeletal dysplasia characterized by recurrent fractures due to congenital bone fragility. The only bisphosphonate approved for OI in Japan is pamidronate (PAM). To investigate whether monthly intravenous alendronate (ALN) infusions can maintain bone strength in OI children following cyclical PAM treatment. Methods A prospective and non-inferiority study was conducted. Eight school-age OI patients aged 8.5±2.0 years who were treated with cyclical PAM for 6.0±2.3 years were enrolled and switched to monthly intravenous ALN (0.030 mg/kg/month). Changes in L1-4 bone mineral density (BMD) Z-scores, fracture rates, and bone turnover markers for 12 months were analyzed. Results Average BMD Z-scores were -3.0±1.9, -2.9±2.0, and -2.2±2.0 in 12 months before enrollment, at enrollment, and after 12 months of ALN treatment, respectively. BMD Z-scores increased significantly during treatment with both PAM and ALN (p=0.012), and the effect of ALN was not inferior to that of PAM (p=0.67). There was no change in fracture rates (p=0.86) and bone turnover markers during the 12 months before and after enrollment. Additionally, ALN showed no remarkable side effects. Conclusions Our results suggest that monthly intravenous ALN can maintain bone strength after primary usage of cyclical PAM. We concluded that monthly intravenous ALN as a maintenance treatment following cyclical PAM administration can be an option for OI children.

Evaluation of Fracture and Osteotomy Union in the Setting of Osteogenesis Imperfecta: Reliability of the Modified Radiographic Union Score for Tibial Fractures (RUST).

BACKGROUND: Evaluation of the union of osteotomies and fractures in patients with osteogenesis imperfecta (OI) is a critical component of patient care. Studies of the OI patient population have so far used varied criteria to evaluate bony union. The radiographic union score for tibial fractures (RUST), which was subsequently revised to the modified RUST, is an objective standardized method of evaluating fracture healing. We sought to evaluate the reliability of the modified RUST in the setting of the tibias of patients with OI. METHODS: Tibial radiographs of 30 patients with OI fractures, or osteotomies were scored by 3 observers on 2 separate occasions. Each of the 4 cortices was given a score (1=no callus, 2=callus present, 3=bridging callus, and 4=remodeled, fracture not visible) and the modified RUST is the sum of these scores (range, 4 to 16). The interobserver and intraobserver reliabilities were evaluated using intraclass coefficients (ICC) with 95% confidence intervals. RESULTS: The ICC representing the interobserver reliability for the first iteration of scores was 0.926 (0.864 to 0.962) and for the second series was 0.915 (0.845 to 0.957). The ICCs representing the intraobserver reliability for each of the 3 reviewers for the measurements in series 1 and 2 were 0.860 (0.707 to 0.934), 0.994 (0.986 to 0.997), and 0.974 (0.946 to 0.988). CONCLUSIONS: The modified RUST has excellent interobserver and intraobserver reliability in the setting of OI despite challenges related to the poor quality of the bone and its dysplastic nature. The application and routine use of the modified RUST in the OI population will help standardize our evaluation of osteotomy and fracture healing. LEVEL OF EVIDENCE: Level III-retrospective study of nonconsecutive patients.

A novel transgenic murine model with persistently brittle bones simulating osteogenesis imperfecta type I.

Osteogenesis imperfecta (OI) type I caused by the null allele of COL1A1 gene is in the majority in clinical OI cases. Currently, heterozygous Mov-13 mice generated by virus insertion in the first intron of col1a1 is the exclusive model to modulate OI type I, in spite of the gradually recovered bone mineral and mechanical properties. A newly designed heterozygous col1a1±365 OI mouse was produced in the present study by partial exons knockout (exon 2-exon 5, 365 nt of mRNA) using CRISPR/Cas9 system. The deletion resulted in generally large decrease in type I collagen synthesis due to frameshift mutation and premature chain termination, closely mimicking the pathogenic mechanism in affected individuals. And the strain possessed significantly sparse mineral scaffolds, bone loss, lowered mechanical strength and broken bone metabolism by 8 and 20 weeks compared to their littermates, suggesting a sustained skeletal weakness. Notably, the remarkable down-regulation of Yes-associated protein (YAP), one of the key coactivator in Hippo signaling pathway, was first found both in the femur and adipose derived mesenchymal stem cells (ADSCs) under osteogenic differentiation of col1a1±365 mice, which might be responsible for the reduced osteogenic potential and brittle bones. Still, further research was needed in order to illuminate the underlying mechanism.

Solanum muricatum Ameliorates the Symptoms of Osteogenesis Imperfecta In Vivo.

Pepino (Solanum muricatum), which is an evergreen plant native to South America, is well-known for its effects in antioxidation, antidiabetic activity, anti-inflammation, and antitumor activity. A previous study in our lab indicated that Solanum muricatum (SM) extract promoted osteogenic differentiation by upregulating Wnt and BMP signaling pathway in rat bone marrow stromal cells. The osteogenesis imperfecta (OI) mouse model was used in order to further discover the osteogenic properties of SM extract in the present research. We utilized microCT analysis to collect bone mass and microarchitectural parameters at vertebrae and at femur metaphysis in OI mice. Raman spectrometry was applied to identify change of bone mineral and matrix composition during SM treatment. Finally, collagen synthesis marker PINP and collagen degradation marker CTX were detected using enzyme immunoassay. SM extract could improve the bone mass and microarchitectural parameters both at vertebrae and at femur metaphysis. It also significantly increased the collagen content by promoting its biosynthesis and inhibiting its degradation. By using heterozygous Col1a1Jrt /+ mice as a model of OI, 6 weeks treatment of SM extract could significantly ameliorate the symptoms in OI mice. Thus, SM holds potential for developing new drugs of bone formation and bone remodeling.

Elastic intramedullary nailing of the femur fracture in patients affected by osteogenesis imperfecta type 3: Indications, limits and pitfalls.

INTRODUCTION: Patients with Osteogenesis Imperfecta (OI) Type 3 may exhibit both primitive deformities and secondary fracture malunions on a femoral level. The orthopaedic surgeon's objective is to cure the deformities in order to prevent fractures and to treat the fractures in order to prevent deformities, by using telescopic nails as the gold standard method of fixation. However, the titanium elastic nail (TEN) is indicated as a possible alternative in certain selected cases. MATERIALS AND METHODS: The Centre for Congenital Osteodystrophy of the Sapienza University of Rome follows 485 patients with osteogenesis imperfecta. For the purpose of this study, we selected 36 patients with OI type 3 (15 females and 21 males), aged between 2 and 10 years old, who were surgically treated for femur fractures with Titanium Elastic Nail (TEN) from January 2007 to December 2009. In 12 cases a single TEN was implanted, while 24 of the cases were treated by implanting 2 TENs with the Sliding Nail (SN) technique. A retrospective evaluation was carried out by analysing the data from the medical charts and dossiers related to pain symptoms, knee and hip Range of Motion (ROM), any possible complications that could cause implant revisions (infections, nail slide failure, nail migration, traumatic events following surgery, delayed consolidation, epiphysiodesis). RESULTS: At the 60th post-surgical month, the revision rate was 75%, mostly due to migration, osteolysis, nail slide failure and nail fracture. The Kaplan-Meier's survival curve analysis showed a coefficient of 0.25-60 months (confidence interval -0.31 and 0.81). DISCUSSION: The percentage of complications and the high rate of revisions recorded in our sample confirm that telescopic nail is the gold standard in the treatment of femoral fractures in patients with OI type 3. CONCLUSIONS: In patients under the age of 4, with narrow medullary canals, low life expectancy, few to nil rehabilitative prospectives or severe comorbidities, the use of TEN may be considered as a less invasive approach compared to telescopic nail surgery, however only temporarily, as it will still most probably require a surgical revision a few years down the line.

WNT1-associated osteogenesis imperfecta with atrophic frontal lobes and arachnoid cysts.

A rare form of osteogenesis imperfecta (OI) caused by Wingless-type MMTV integration site family 1 (WNT1) mutations combines central nervous system (CNS) anomalies with the characteristic increased susceptibility to fractures. We report an additional case where arachnoid cysts extend the phenotype, and that also confirms the association of intellectual disabilities with asymmetric cerebellar hypoplasia here. Interestingly, if the cerebellum is normal in this disorder, intelligence is as well, analogous to an association with similar delays in a subset of patients with sporadic unilateral cerebellar hypoplasia. Those cases typically appear to represent vascular disruptions, and we suggest that most brain anomalies in WNT1-associated OI have vascular origins related to a role for WNT1 in CNS angiogenesis. This unusual combination of benign cerebellar findings with effects on higher functions in these two situations raises the possibility that WNT1 is involved in the pathogenesis of the associated sporadic cases as well. Finally, our patient reacted poorly to pamidronate, which appears ineffective with this form of OI, so that a lack of improvement is an indication for molecular testing that includes WNT1.

An update on the role of RANKL-RANK/osteoprotegerin and WNT-ß-catenin signaling pathways in pediatric diseases.

BACKGROUND: Bone remodeling is a lifelong process due to the balanced activity of osteoclasts (OCs), the bone-reabsorbing cells, and osteoblasts (OBs), and the bone-forming cells. This equilibrium is regulated by numerous cytokines, but it has been largely demonstrated that the RANK/RANKL/osteoprotegerin and Wnt/ß-catenin pathways play a key role in the control of osteoclastogenesis and osteoblastogenesis, respectively. The pro-osteoblastogenic activity of the Wnt/ß-catenin can be inhibited by sclerostin and Dickkopf-1 (DKK-1). RANKL, sclerostin and DKKs-1 are often up-regulated in bone diseases, and they are the target of new monoclonal antibodies. DATA SOURCES: The authors performed a systematic literature search in PubMed and EMBASE to June 2018, reviewed and selected articles, based on pre-determined selection criteria. RESULTS: We re-evaluated the role of RANKL, osteoprotegerin, sclerostin and DKK-1 in altered bone remodeling associated with some inherited and acquired pediatric diseases, such as type 1 diabetes mellitus (T1DM), alkaptonuria (AKU), hemophilia A, osteogenesis imperfecta (OI), 21-hydroxylase deficiency (21OH-D) and Prader-Willi syndrome (PWS). To do so, we considered recent clinical studies done on pediatric patients in which the roles of RANKL-RANK/osteoprotegerin and WNT-ß-catenin signaling pathways have been investigated, and for which innovative therapies for the treatment of osteopenia/osteoporosis are being developed. CONCLUSIONS: The case studies taken into account for this review demonstrated that quite frequently both bone reabsorbing and bone deposition are impaired in pediatric diseases. Furthermore, for some of them, bone damage began in childhood but only manifested with age. The use of denosumab could represent a valid alternative therapeutic approach to improve bone health in children, although further studies need to be carried out.

Mecanismos involucrados en la fragilidad ósea en diabetes mellitus / Mechanisms involved in the bone fragility in diabetes mellitus

La diabetes es una enfermedad crónica asociada con importantes comorbilidades. El sistema esquelético parece ser un objetivo adicional de daño mediado por diabetes. Se acepta que la diabetes tipo 1 y tipo 2 se asocian con un mayor riesgo de fractura ósea. Varios estudios han demostrado que los cambios metabólicos causados por la diabetes pueden influir en el metabolismo óseo disminuyendo la calidad y la resistencia del hueso. Sin embargo, los mecanismos subyacentes no se conocen por completo pero son multifactoriales y, probablemente, incluyen los efectos de la obesidad, hiperglucemia, estrés oxidativo y acumulación de productos finales de glicosilación avanzada. Estos darían lugar a un desequilibrio de varios procesos y sistemas: formación de hueso, resorción ósea, formación y entrecruzamiento de colágeno. Otros factores adicionales como la hipoglucemia inducida por el tratamiento, ciertos medicamentos antidiabéticos con un efecto directo sobre el metabolismo óseo y mineral, así como una mayor propensión a las caídas, contribuirían al aumento del riesgo de fracturas en pacientes con diabetes mellitus. Esta revisión tiene como objetivo describir los mecanismos fisiopatológicas subyacentes a la fragilidad ósea en pacientes diabéticos. (AU)

Diabetes is a chronic disease associated with important comorbidities. The skeletal system seems to be an additional target of diabetes mediated damage. It is accepted that type 1 and type 2 diabetes are associated with an increased risk of bone fracture. Several studies have shown that metabolic changes caused by diabetes can influence bone metabolism by decreasing bone quality and resistance. However, the underlying mechanisms are not completely known but they are multifactorial and probably include the effects of obesity, hyperglycemia, oxidative stress and accumulation of advanced glycosylation end products. These would lead to an imbalance of several processes and systems: bone formation, bone resorption, formation and collagen crosslinking. Other additional factors such as treatment-induced hypoglycemia, certain antidiabetic medications with a direct effect on bone and mineral metabolism, as well as an increased propensity for falls, would contribute to the increased risk of fractures in patients with diabetes mellitus. This review aims to describe the pathophysiological mechanisms underlying bone fragility in diabetic patients. (AU)

Anesthesia in children with osteogenesis imperfecta: Retrospective chart review of 83 patients and 205 anesthetics over 7 years.

BACKGROUND: Osteogenesis imperfecta is the collective term for a heterogeneous group of connective tissue syndromes characterized by bone fragility with multisystem involvement and perioperative implications. AIMS: Literature review of anesthetic management of patients with osteogenesis imperfecta revealed a paucity of data on the incidence of perioperative challenges. We sought to determine the rates of these challenges in our study cohort. METHODS: Data were collected in a specialty orthopedic hospital from 2008 to 2015 for 83 osteogenesis imperfecta patients undergoing 205 surgeries: 203 orthopedic surgeries and 2 mid-face reconstructive surgeries. Airway management, intravenous access, surgical blood loss, use of peripheral nerve blockade and/or neuraxial techniques, presence of perioperative fracture, and peak intraoperative temperature were evaluated and analyzed. RESULTS: Difficult airway was encountered in 3/205 (1.5%) cases and perioperative fracture in 2/205 (1%) cases. Neuraxial anesthesia was attempted in 64/205 cases with an 87.5% success rate. All peripheral nerve block attempts (33/205 cases) were successful. Difficult intravenous catheter placement was noted in 8/205 (4%) cases. Estimated blood loss >10% of estimated blood volume was considered significant, and occurred in 35/205 (17%) cases. Significant blood loss occurred more often in severe osteogenesis imperfecta types: 18/76 (23.7%) in Type III and 11/65 (16.9%) in Type IV, whereas only 4/47 (8.5%) occurred in mild Type I. In our 205 case cohort, osteogenesis imperfecta Type III had 5.6 times the odds [(95% CI = 1.8-17.2) P = 0.003] of having an anesthetic complication as compared to osteogenesis imperfecta Type I. CONCLUSION: Patients with osteogenesis imperfecta undergo frequent anesthetic exposures, but anesthetic challenges in our series were uncommon. Odds of challenges are greater in severe osteogenesis imperfecta Type III, with significant blood loss and difficulty placing intravenous catheters more likely encountered in the more severe types.

Dual Interlocking Telescopic Rod Provides Effective Tibial Stabilization in Children With Osteogenesis Imperfecta.

BACKGROUND: Interlocking telescopic rods for the management of osteogenesis imperfecta (OI)-related long bone fractures are a modification of the Sheffield rod. An interlocking pin anchors the obturator at the distal epiphysis, which spares the distal joint, while a T-piece anchors the sleeve at the proximal epiphysis. However, these devices are associated with some problems, including failure to elongate and difficulty with removal. A dual interlocking telescopic rod (D-ITR), in which the sleeve and the obturator are anchored with interlocking pins, was developed to address these problems. QUESTIONS/PURPOSES: In this study, we compared the D-ITR with an older version of a single interlocking telescopic rod (S-ITR) based on (1) surgery-free survival and rod survival; (2) cessation of rod elongation and elongated length of the rod; and (3) risk of refracture and complications related to the interlocking telescopic system. METHODS: This article compares the D-ITR with the S-ITR using a historically controlled, single-surgeon, retrospective design comparing two implants for the management of fractures in children with OI. Before August 2007, we exclusively used the S-ITR (n = 17 patients, 29 tibiae); from July 2008 until October 2014, we exclusively used the D-ITR (n = 17 patients, 26 tibiae). During the 1-year transition period, we performed five of these procedures (two S-ITR in two patients and three D-ITR in three patients), and implant use was based on availability with our preference being the D-ITR during that time when it was available. The general indications for use of both devices were the same: patients with OI and a tibial fracture who were older than 3 to 4 years of age and whose tibial canals were wide enough to accept an intramedullary rod. Younger patients were treated other ways (generally without surgery) and those with narrower canals with thinner, nonelongating rods or Kirschner wires, as indicated. All patients in both groups were available for followup at a minimum of 2 years (mean ± SD, 9.6 ± 3.0 years in the S-ITR group and 5.3 ± 2.1 years in the D-ITR group) except for one patient in the D-ITR group who died > 1 year after the procedure resulting from reasons unrelated to it. For the between-group comparison, we used only the followup data collected up to the ninth postoperative year in the S-ITR group. The truncated followup period of the S-ITR group was a mean of 5.0 ± 1.6 years. The mean age in the S-ITR group was 7 years (range, 3-12 years) and it was 8 years (range, 3-14 years) in the D-ITR group. There were nine boys and 10 girls in each group. Two orthopaedic surgeons other than the operating surgeon performed chart review to address our three research purposes. Survival analyses were performed using the Kaplan-Meier method. The overall pooled risk of refracture and major complications potentially associated with the interlocking telescopic rod system was compared between the groups. RESULTS: With the numbers available, there were no differences between the D-ITR and the S-ITR in terms of mean surgery-free survival time (5.7 [95% confidence interval {CI}, 4.5-6.9] versus 5.1 [95% CI, 4.1-6.1]; years; p = 0.653) or mean rod survival time (7.4 [95% CI, 6.4-8.4] versus 6.0 [95% CI, 5.1-6.9] years; p = 0.120). With the numbers available, cessation of elongation (4% in the D-ITR group versus 19% in the S-ITR group; p = 0.112) and elongated length (45.3 ± 24.3 mm in the D-ITR group versus 44.2 ± 22.3 mm in the S-ITR group; p = 0.855) also did not differ between the groups. The pooled proportions of refracture or complications after the index surgery were higher in the S-ITR group (25 tibias [81%]) than in the D-ITR group (15 tibias [54%]; p = 0.049). Eight tibias in the S-ITR group had proximal migration of the sleeve compared with no patients in the D-ITR group (p = 0.005). CONCLUSIONS: In patients with OI, the modified D-ITR provides effective tibial stabilization with similar or better results than the S-ITR design. Anchoring the sleeve at the proximal epiphysis with an interlocking pin provides better anchorage and allows easier removal. LEVEL OF EVIDENCE: Level III, therapeutic study.

Anesthetic considerations for scoliosis surgery in a patient with recessive severe/lethal form of osteogenesis imperfecta.

Osteogenesis imperfecta is a heterogeneous genetic disorder characterized by bone fragility, with disease ranging from mild fractures to death in utero. We describe a child with autosomal recessive osteogenesis imperfecta type VIII (severe or lethal phenotype), who successfully underwent posterior spinal fusion, was extubated on postoperative day 1 and discharged home 25 days later. Recently identified recessive forms of osteogenesis imperfecta are associated with severe/lethal phenotype. Special consideration is needed in scoliosis surgery, with challenges arising from prone positioning, neurophysiology monitoring, and blood loss.

Mutations That Alter the Carboxy-Terminal-Propeptide Cleavage Site of the Chains of Type I Procollagen Are Associated With a Unique Osteogenesis Imperfecta Phenotype.

Osteogenesis imperfecta (OI) is a genetic bone disorder characterized by fractures, low bone mass, and skeletal fragility. It most commonly arises from dominantly inherited mutations in the genes COL1A1 and COL1A2 that encode the chains of type I collagen. A number of recent reports have suggested that mutations affecting the carboxyl-terminal propeptide cleavage site in the products of either COL1A1 or COL1A2 give rise to a form of OI characterized by unusually dense bones. We have assembled clinical, biochemical, and molecular data from 29 individuals from 8 families with 7 different mutations affecting the C-propeptide cleavage site. The phenotype was generally mild: The median height was ∼33th centile. Eighty percent of subjects had their first fracture by the age of 10 years, and one-third had a femoral or tibial fracture by the age of 25 years. Fractures continued into adulthood, though rates varied considerably. Healing was normal and rarely resulted in long bone deformity. One-third of subjects older than 15 years had scoliosis. The teeth and hearing were normal in most, and blue sclerae were not observed. Other features noted included fibro-osseous dysplasia of the mandible and Achilles tendon calcification. The mean spinal bone mineral density Z-score was +2.9 (SD 2.1) compared with -2.2 (0.7) in subjects with COL1A1 haploinsufficiency mutations. Bone mineral density distribution, assessed by quantitative backscattered electron imaging in bone showed higher levels of mineralization than found in any other disorder. Bone histology showed high trabecular volume and increased cortical thickness, with hyperosteoidosis and delayed mineralization. In vitro studies with cultured skin fibroblasts suggested that these mutations interfere with processing of the chain in which the sequence alteration occurs, but the C-propeptide is eventually cleaved (and detectable in blood), suggesting there are alternative sites of cleavage. The precise mechanism of the bony pathology is not yet clear. © 2018 American Society for Bone and Mineral Research.

Health-related quality of life of children and adolescents with osteogenesis imperfecta: a cross-sectional study using PedsQL™.

BACKGROUND: Osteogenesis imperfecta (OI) is a disorder of bone formation leading to low mineral density and fractures. Children and adolescents with OI require periodic medical follow up, corrective surgery, drug therapy and physical therapy, as well as specific daily care practices. In addition, they have an increased incidence of fractures, which require immobilization and cause severe discomfort and short-term disability. This study evaluated the health-related quality of life of children and adolescents with OI in two reference centers for OI treatment in southern Brazil. METHODS: In this prospective cross-sectional study, the Pediatric Quality of Life Inventory (PedsQLTM) was applied in two university-affiliated reference centers for OI treatment in southern Brazil. Children and adolescents aged ≥ 5 years with clinical diagnoses of OI were included. Clinical data and socioeconomic status was evaluated. RESULTS: The sample consisted of 52 children and adolescents with OI (aged 5-17 years); 26 (50%) participants with type I OI, 13 (25%) type IV, 12 (23.1 %) type III, and 1 (1.9%) type V OI. Physical and social functioning domains differed significantly according to clinical presentation of OI with lowest scores in the severe type (OI type III). Pain seems to be the variable that is most associated with impact on the PedsQL domains. CONCLUSIONS: Overall, this study revealed differences in physical functioning and social functioning in relation to OI clinical presentation. These results reinforcing the importance of the clinical management of these patients with the aim of functional improvement and importance of pain control.

Elevated platelet counts in a cohort of children with moderate-severe osteogenesis imperfecta suggest that inflammation is present.

BACKGROUND: Elevated platelet counts are observed in cancer, autoimmunity and inflammation with concurrent illness. Proinflammatory cytokines are elevated in murine osteogenesis imperfecta (OI) models. We hypothesised that platelet counts might be elevated in children with moderate-severe OI. METHODS: We reviewed the hospital records of 71 children with moderate-severe OI, treated in the Sheffield Children's Hospital's Severe, Complex and Atypical Osteogenesis Imperfecta Highly Specialised Service. Data relating platelet count (below/above average, above upper limit) to prior and concurrent events were summarised as event proportions per child. Additionally, we created platelet SD scores to assess age and time-related trends, and relationship with OI type. RESULTS: 1206 platelet counts were recorded. Platelet SD scores were right-shifted by 0.89 SD overall. 49 of 71 (69%) patients had at least one platelet count above the normal range and 246 (20.4%) of all counts were above the upper limit of normal. Of these, 101 (41%) were high despite no confounding factors being present. For the 47 children with data at age less than 2 years, 89 (30.0%) platelet counts were above the upper limit of normal and 39 (44%) had no associated confounding factor. Elevated platelet counts were recorded most often for children with new or existing vertebral fractures. CONCLUSIONS: Raised platelet counts were observed in association with new and healing vertebral fractures, but also (41%-44%) in the absence of identified proinflammatory factors or events. We speculate that these findings are evidence for a proinflammatory component to OI that could be a target for therapeutic intervention.

P4HB recurrent missense mutation causing Cole-Carpenter syndrome.

BACKGROUND: Cole-Carpenter syndrome (CCS) is commonly classified as a rare Osteogenesis Imperfecta (OI) disorder. This was following the description of two unrelated patients with very similar phenotypes who were subsequently shown to have a heterozygous missense mutation in P4HB. OBJECTIVES: Here, we report a 3-year old female patient with severe OI who on exome sequencing was found to carry the same missense mutation in P4HB as reported in the original cohort. We discuss the genetic heterogeneity of CCS and underlying mechanism of P4HB in collagen production. METHODS: We undertook detailed clinical, radiological and molecular phenotyping in addition, to analysis of collagen in cultured fibroblasts and electron microscopic examination in the patient reported here. RESULTS: The clinical phenotype appears consistent in patients reported so far but interestingly, there also appears to be a definitive phenotypic clue (crumpling metadiaphyseal fractures of the long tubular bones with metaphyseal sclerosis which are findings that are uncommon in OI) to the underlying genotype (P4HB variant). DISCUSSION: P4HB (Prolyl 4-hydroxylase, betasubunit) encodes for PDI (Protein Disulfide isomerase) and in cells, in its tetrameric form, catalyses formation of 4-hydroxyproline in collagen. The recurrent variant in P4HB, c.1178A>G, p.Tyr393Cys, sits in the C-terminal reactive centre and is said to interfere with disulphide isomerase function of the C-terminal reactive centre. P4HB catalyses the hydroxylation of proline residues within the X-Pro-Gly repeats in the procollagen helical domain. Given the inter-dependence of extracellular matrix (ECM) components in assembly of a functional matrix, our data suggest that it is the organisation and assembly of the functional ECM that is perturbed rather than the secretion of collagen type I per se. CONCLUSIONS: We provide additional evidence of P4HB as a cause of a specific form of OI-CCS and expand on response to treatment with bisphosphonates in this rare disorder.

Management of atypical femoral fracture in a patient with osteogenesis imperfecta.

Osteogenesis imperfecta (OI) is a generalised connective tissue disorder associated with low bone mass, bone fragility and increased susceptibility to fractures. First-line treatment to improve bone mineral density (BMD) is usually with bisphosphonates but long-term usage has been associated with uncommon complications such as atypical femoral fractures (AFF). Treatment with teriparatide in this situation has been reported with positive outcomes. However, choice of treatment after 2 years of teriparatide has not been well studied or reported. We describe a patient with OI treated with bisphosphonates for 9 years, who then suffered a spontaneous AFF, was subsequently started on teriparatide for 2 years followed by 6 monthly Denosumab. 1 year post-treatment with Denosumab, there was significant improvement in BMD, good fracture healing and no new fractures. This case highlights the potential use of denosumab following 2 years of teriparatide treatment in patients with OI with AFF.