Heike Hoyer-Kuhn

Mutations in SEC24D, Encoding a Component of the COPII Machinery, Cause a Syndromic Form of Osteogenesis Imperfecta

As a result of a whole-exome sequencing study, we report three mutant alleles in SEC24D, a gene encoding a component of the COPII complex involved in protein export from the ER: the truncating mutation c.613C>T (p.Gln205(∗)) and the missense mutations c.3044C>T (p.Ser1015Phe, located in a cargo-binding pocket) and c.2933A>C (p.Gln978Pro, located in the gelsolin-like domain). Three individuals from two families affected by a similar skeletal phenotype were each compound heterozygous for two of these mutant alleles, with c.3044C>T being embedded in a 14 Mb founder haplotype shared by all three. The affected individuals were a 7-year-old boy with a phenotype most closely resembling Cole-Carpenter syndrome and two fetuses initially suspected to have a severe type of osteogenesis imperfecta. All three displayed a severely disturbed ossification of the skull and multiple fractures with prenatal onset. The 7-year-old boy had short stature and craniofacial malformations including macrocephaly, midface hypoplasia, micrognathia, frontal bossing, and down-slanting palpebral fissures. Electron and immunofluorescence microscopy of skin fibroblasts of this individual revealed that ER export of procollagen was inefficient and that ER tubules were dilated, faithfully reproducing the cellular phenotype of individuals with cranio-lentico-sutural dysplasia (CLSD). CLSD is caused by SEC23A mutations and displays a largely overlapping craniofacial phenotype, but it is not characterized by generalized bone fragility and presented with cataracts in the original family described. The cellular and morphological phenotypes we report are in concordance with the phenotypes described for the Sec24d-deficient fish mutants vbi (medaka) and bulldog (zebrafish).

Two years’ experience with denosumab for children with Osteogenesis imperfecta type VI

BackgroundOsteogenesis imperfecta (OI) is a hereditary disease causing reduced bone mass, increased fracture rate, long bone deformities and vertebral compressions. Additional non skeletal findings are caused by impaired collagen function and include hyperlaxity of joints and blue sclera. Most OI cases are caused by dominant mutations in COL1A1/2 affecting bone formation. During the last years, recessive forms of OI have been identified, mostly affecting posttranslational modification of collagen. In 2011, mutations in SERPINF1 were identified as the molecular cause of OI type VI, and thereby a novel pathophysiology of the disease was elucidated. The subgroup of patients with OI type VI are affected by an increased bone resorption, leading to the same symptoms as observed in patients with an impaired bone formation. Severely affected children are currently treated with intravenous bisphosphonates regardless of the underlying mutation and pathophysiology. Patients with OI type VI are known to have a poor response to such a bisphosphonate treatment.MethodDeciphering the genetic cause of OI type VI in our 4 patients (three children and one adolescent) led to an immediate translational approach in the form of a treatment with the monoclonal RANKL antibody Denosumab (1 mg/kg body weight every 12 weeks).ResultsShort-term biochemical response to this treatment was reported previously. We now present the results after 2 years of treatment and demonstrate a long term benefit as well as an increase of bone mineral density, a normalization of vertebral shape, an increase of mobility, and a reduced fracture rate.ConclusionThis report presents the first two-year data of denosumab treatment in patients with Osteogenesis imperfecta type VI and in Osteogenesis imperfecta in general as an effective and apparently safe treatment option.

Effect of Denosumab on the Growing Skeleton in Osteogenesis Imperfecta

Children with increased bone fragility have been treated frequently with iv bisphosphonates based on experiences in children with osteogenesis imperfecta (OI) (1). In growing children, each infusion led to a region with reduced bone resorption known as “zebra lines” on radiographs and changes in metaphyseal shaping (2). First short-term experiences about the use of the RANKL-antibody denosumab in children are available. Wang and colleagues recently reported radiological and histological changes after denosumab treatment in a boy with the rare condition, fibrous dysplasia, after amputation of both legs (3). Now we report two children with OI caused by mutations in COL1A1/A2 who received bisphosphonates for more than 4 years and switched to denosumab (1 mg/kg body weight every 12 wk) according to the regime published in other OI children (4). On the presented x-rays, the effect of denosumab is clearly visible (Figure 1). Zebra lines of the previous treatment are still visible, whereas the bone produced between the denosumab injections showed an increased density, demonstrating the long-lasting effect of denosumab (Figure 1, B–D). This gives evidence that longitudinal growth continues. Metaphyseal shaping including the metaphyseal index showed a trend toward the normal range but remained above 2 SD compared to healthy children (patient 1, baseline vs months 8, 0.65/0.63; patient 2, wk 3 vs week 9, 0.73/0.61) (5). Further long-term observations are needed to assess metaphyseal in-wasting processes under denosumab. In summary, these x-rays are the first demonstrating the effect of denosumab in OI supporting the promising reports about denosumab in growing children.

A nonclassical IFITM5 mutation located in the coding region causes severe osteogenesis imperfecta with prenatal onset.

Osteogenesis imperfecta (OI) is a hereditary connective tissue disorder characterized by a wide range of skeletal symptoms. Most patients have dominantly inherited or de novo mutations in COL1A1 or COL1A2. Up to 5% of patients have OI type V, characterized by hyperplastic callus formation after fractures, calcification of the interosseous membrane of the forearm, and a mesh‐like lamellation pattern observed in bone histology. Recently, a heterozygous mutation in the 5′‐untranslated region (UTR) of IFITM5 (c.–14C > T) was identified as the underlying cause of OI type V, and only this specific mutation was subsequently identified in all patient cohorts with this OI subtype. We now present a case of a heterozygous mutation within the coding region of IFITM5 (c.119C > T; p.S40L). The mutation occurred de novo in the patient and resulted in severe OI with prenatal onset and extreme short stature. At the age of 19 months, the typical clinical hallmarks of OI type V were not present. Our finding has important consequences for the genetic “work‐up” of patients suspected to have OI, both in prenatal and in postnatal settings: The entire gene—not only the 5′‐UTR harboring the “classical” OI type V mutation—has to be analyzed to exclude a causal role of IFITM5. We propose that this should be part of the initial diagnostic steps for genetic laboratories performing SANGER sequencing in OI patients.

Comparison of DXA Scans and Conventional X-rays for Spine Morphometry and Bone Age Determination in Children.

Conventional lateral spine and hand radiographs are the standard tools to evaluate vertebral morphometry and bone age in children. Beside bone mineral density analyses, dual-energy X-ray absorptiometry (DXA) measurements with lower radiation exposure provide high-resolution scans which are not approved for diagnostic purposes. Data about the comparability of conventional radiographs and DXA in children are missing yet. The purpose of the trial was to evaluate whether conventional hand and spine radiographs can be replaced by DXA scans to diminish radiation exposure. Thirty-eight children with osteogenesis imperfecta or secondary osteoporosis or short stature (male, n=20; age, 5.0-17.0 yr) were included and assessed once by additional DXA (GE iDXA) of the spine or the left hand. Intraclass correlation coefficients (ICCs) were used to express agreement between X-ray and iDXA assessment. Evaluation of the spine morphometry showed reasonable agreement between iDXA and radiography (ICC for fish-shape, 0.75; for wedge-shape, 0.65; and for compression fractures, 0.70). Bone age determination showed excellent agreement between iDXA and radiography (ICC, 0.97). IDXA-scans of the spine in a pediatric population should be used not only to assess bone mineral density but also to evaluate anatomic structures and vertebral morphometry. Therefore, iDXA can replace some radiographs in children with skeletal diseases.

Knochengesundheit bei Kindern

„Knochenstoffwechselstörungen“ aufgrund von Mangelernährung, wie sie zu Beginn des letzten Jahrhunderts häufig auftraten, sind heute in den Hintergrund getreten. Jedoch führen Änderungen des Lebensstils in den westlichen Nationen mit ihren Ernährungsgewohnheiten und dem veränderten Konzept von Arbeit und Freizeit zu Störungen im Knochenstoffwechsel und Wachstum.

P150 – 2879: Summary of results for intensive physiotherapy combined with home-based training in different movement disorders

Objective Evidence is accumulating for physiotherapy strategies including vibration assisted therapy for improving mobility and function (Novak et al. 2013). An innovative new routine procedure of the German health care system combines interval-rehabilitation with home-based vibration training. We are presenting the summarised results for motor function after 6 months of training and 6 months follow-up for 3 groups of children: cerebral palsy (CP), spina bifida and osteogenesis imperfecta (OI). Methods Retrospective analysis of 6 months of home-based vibration training combined with interval blocks at the University Hospital Cologne: 13 days at the beginning, and 6 days after 3 months. Measurements were taken at the beginning (M0), after 6 months (M6) and after 6 months follow up (M12). Motor function was assessed by the Gross Motor Function Measure (GMFM-66). In total 469 patients were analysed: 356 children with CP (mean age 8.9±4.4 years, GMFCS-Level I-IV), 60 with spina bifida (mean age 8.71±4.7 years) and 53 with OI (mean age 9.1±0.61 SEM years). Results In the CP group the GMFM-66 improved by 3.35 points (p Conclusion Two blocks of intensive physiotherapy combined with home-based vibration training showed a significant positive effect on motor function in patients with CP, spina bifida and OI. The results could be sustained after 6 months follow-up, but did not change significantly anymore. All change scores exceed the minimum clinically important difference of 1.8 for a large effect size reported by Oeffinger et al.2008. This retrospective evaluation of clinical data supports the evidence for intensive, goal directed and technology assisted physiotherapy.

Growth response to growth hormone treatment in patients with SHOX deficiency can be predicted by the Cologne prediction model

Abstract Background Growth hormone (GH) treatment in children with short stature homeobox-containing gene (SHOX) deficiency is recognized to increase height velocity (HV) and adult height. Prediction of growth response continues to be a challenge. A comparatively accurate method is the Cologne prediction model developed in children with GH deficiency. The aim was to investigate whether this model also applies to patients with SHOX deficiency. Methods Included were 48 patients with SHOX deficiency confirmed by DNA analysis and treated with 0.05 mg/kg/day of somatropin. Prediction by the Cologne model uses the following variables: relative bone age (BA) retardation, baseline insulin-like growth factor-I (IGF-I), urinary deoxypyridinoline (DPD) cross-links at 4 weeks and HV at 3 months. Results HV and height standard deviation scores (SDS) increased significantly during the first year of treatment. Predicted and observed HV (cm/year) showed a Pearson correlation coefficient of 0.50 (p<0.001; root-mean-square error=1.63) and for first-year change in height SDS a Pearson correlation coefficient of 0.751 (p<0.001; root-mean-square error=0.32). Poor response could be adequately predicted using SDS change, with sensitivity and specificity both above 70% for certain thresholds. Conclusions: The results demonstrate that the Cologne model can be used to predict growth response in patients with SHOX deficiency with reasonable precision in the first treatment year, comparable to prediction in patients with GH deficiency.

Systematic review of the effect of denosumab on children with osteogenesis imperfecta showed inconsistent findings

Osteogenesis imperfecta (OI) is a rare, inherited disorder characterised by increased bone fragility, reduced bone mass and often short stature. Most cases are due to mutations in one of the two genes encoding collagen type 1 – COL1A1 and COL1A2 (1) – and the signs and symptoms vary substantially with the disease severity. The risk of fractures is 100 times higher than the general population, even in patients with mild OI. Bisphosphonates are the current standard pharmacotherapy for managing and treating patients with severe OI, but concerns about their long-term safety have been raised (1). Denosumab is a RANK ligand antibody that prevents RANKL ligand–RANK interaction and inhibits osteoclast formation, thus reducing bone resorption, which has been approved to treat postmenopausal osteoporosis. Its effects on osteoclast may make it suitable for patients with OI, and this systematic review summarises the most recent evidence from clinical studies exploring its potential for paediatric OI cases. We systematically searched the MedLine and EMBASE databases from 1946 to April 24, 2017 using the terms RANK or denosumab or prolia and OI, and PUBMED to August 31, 2017. Two reviewers (GL and YJ) independently screened the records, chose eligible studies, extracted relevant data and assessed references in the included papers. We included clinical observational research or intervention studies that provided original data on outcomes of denosumab in children with OI. The exclusion criteria included non-clinical research, studies without primary data, such as reviews, commentaries, letters and perspectives, and duplicate, updated and adult studies. Our primary clinical outcomes included bone mineral density (BMD) and fracture incident rates. The secondary outcomes were biomarkers of bone resorption (N-terminal telopeptide of type 1 collagen and deoxypyridinoline), biomarkers of bone formation (procollagen-1C-peptide and osteocalcin), calcium levels, parathyroid hormone levels, bone morphometry and microstructure, changes in body length, mobility, adverse events and quality of life. Descriptive data for the included studies were general characteristics, study procedure – denosumab administration including dosages and intervals and study period – and their main findings. No predefined quantitative syntheses were conducted due to the potential heterogeneity of included studies. Two pilot prospective trials (2,3) and one case report (4) involving a total of 15 children were included (Fig. 1, Table 1). One trial (3) comprised four children who were diagnosed with type VI OI and had a poor response to bisphosphonates treatment but then showed a notable improvement in BMD and bone resorption and formation biomarkers with denosumab. Two children later experienced fractures caused by mild trauma. Another trial (2) focused on 10 children diagnosed with type I, III and IV OI and reported that denosumab significantly improved BMD by week 48. Four fractures due to trauma were reported. However, the N-terminal telopeptide of type 1 collagen levels tended to increase, while the osteocalcin levels tended to decrease. The case report (4) was a clinical observation in a type VI OI child, with a mutation in SERPINF1, who received denosumab at 23 months and displayed no clinical improvement in BMD or fractures. Records identified through database searching (n = 176) Additional records identified through other sources (n = 12) and from updated search on PUBMED (n = 16)

Children with severe Osteogenesis imperfecta and short stature present on average with normal IGF-I and IGFBP-3 levels.

Abstract Background: Osteogenesis imperfecta (OI) is characterized by bone fragility and short stature. Data about IGF-I/IGFBP-3 levels are rare in OI. Therefore IGF-I/IGFBP-3 levels in children with different types of OI were investigated. Methods: IGF-I and IGFBP-3 levels of 60 children (male n=38) were assessed in a retrospective cross-sectional setting. Results: Height/weight was significant different [height z-score type 3 versus type 4: p=0.0011 and weight (p≤0.0001)] between OI type 3 and 4. Mean IGF-I levels were in the lower normal range (mean±SD level 137.4±109.1 μg/L). Mean IGFBP-3 measurements were in the normal range (mean±SD 3.105±1.175 mg/L). No significant differences between OI type 3 and 4 children have been observed (IGF-I: p=0.0906; IGFBP-3: p=0.2042). Conclusions: Patients with different severities of OI have IGF-I and IGFBP-3 levels in the lower normal range. The type of OI does not significantly influence these growth factors.