Nick Shaw

Growth in Sotos syndrome

Although there are several reports on infant and childhood growth in patients with Sotos syndrome, there is little information on the final height achieved and puberty. Growth data on 40 patients (20 female and 20 male) aged 2–31 years were collected. These showed that patients with Sotos syndrome are excessively tall at birth, during infancy, and during childhood. Disproportionately long limbs constitute much of the increase in stature. However, the combination of advanced bone age and early onset of menarche led to a mean (SD) final height of 172.9 (5.7)u2009cm in women. This is within the normal range for the population. Most of the men also attained a final height (mean, 184.3u2009cm; SD, 6.0) within the normal range, although exceptions were more likely in men than in women. Therefore, these results show that most patients with Sotos syndrome do not require intervention to limit their adult height.

Prevention and consequences of vitamin D deficiency in pregnant and lactating women and children: A symposium to prioritise vitamin D on the global agenda

The Department of Nutrition for Health and Development of the World Health Organization (WHO) in collaboration with the Executive Committee of the 18th Vitamin D Workshop (VDW), organised a joint symposium on the prevention and consequences of vitamin D deficiency in pregnant women and children, convening experts on vitamin D, clinicians and policy-makers. The overall aim was to identify priority areas for research and to discuss the need for global options for policy, with a focus on the prevention of rickets in infants and children and vitamin D deficiency in pregnant women. The scope and purpose were: (i) to present the WHO research strategy for health, addressing vitamin D-related public health problems and the process for the development of evidence-informed guidelines in general and how vitamin D interventions in diverse populations could be prioritised; (ii) to provide an overview of vitamin D status in children and pregnant and lactating women across the world; (iii) to review the health risks associated with vitamin D deficiency in children and in pregnant women and their offspring; (iv) to understand the aetiology of vitamin D deficiency in pregnant women and children; (v) to identify and interpret biomarkers to assess vitamin D status and to consider possible clinical and biochemical screening tools for determining the prevalence of nutritional rickets in at risk groups or communities; and (vi) to provide an overview of policies and recommendations on vitamin D across the world. The format of the symposium was a composite of comprehensive scientific presentations and a panel debate with international experts on WHO guidelines, nutritional rickets, nutritional policy and consequences of vitamin D deficiency during pregnancy. This paper summarizes the content and outcomes of the panel debate.

Vertebral fractures assessment in children: Evaluation of DXA imaging versus conventional spine radiography

Vertebral fracture assessment (VFA) by DXA is an accepted tool in adults. However, its use in children has not been assessed. The aim of this study was to evaluate DXA VFA and morphometric analysis (MXA) using a GE Lunar iDXA bone densitometer against spinal radiographic assessment (RA) for the identification of vertebral fractures in children. Spine RA and VFA (T3-L5) were acquired on the same day in 80 children. Forty children considered high risk for fracture by their metabolic bone specialist were referred for spinal RA. Another 40 children were recruited as part of a prospective fracture study and were considered low risk for vertebral fracture. Agreement between RA and VFA was assessed by an expert paediatric radiologist and two paediatricians with expertise in bone pathology. Agreement between RA and MXA was assessed by an expert paediatric radiologist, two clinical scientists and an experienced paediatric radiographer. Vertebrae were ranked as normal, mild, moderate or severe if they had <10%, 11-25%, 26-50% and >50% deformity, respectively. Levels of agreement were calculated using the Cohen kappa score. Evaluating the data from all readable vertebrae, 121 mild, 44 moderate and 16 severe vertebral fractures were identified; with 26, 8, and 5 subjects having at least one mild, moderate or severe fracture, respectively. Depending on rater, 92.8-94.8% of the vertebrae were evaluable by RA. In contrast, 98.4% were evaluable by VFA and only 83.6% were evaluable by MXA. Moderate agreement was found between raters for RA [kappa 0.526-0.592], and VFA [kappa 0.601-0.658] and between RA and VFA [kappa 0.630-0.687]. In contrast, only slight agreement was noted between raters for MXA [kappa 0.361-0.406] and between VFA and MXA [kappa 0.137-0.325]. Agreement substantially improved if the deformities were dichotomised as normal or mild versus moderate or severe [kappa 0.826-0.834]. For the detection of moderate and/or severe fractures the sensitivities & specificities were 81.3% & 99.3%, and 62.5% & 99.2% for VFA and MXA, respectively. This study demonstrates that VFA is as good as RA for detecting moderate and severe vertebral fractures. Given the significant radiation dose saving of VFA compared with RA, VFA is recommended as a diagnostic tool for the assessment of moderate or severe vertebral fracture in children.

Phenotypic variability in patients with osteogenesis imperfecta caused by BMP1 mutations

Osteogenesis Imperfecta (OI) is an inherited bone fragility disorder most commonly associated with autosomal dominant mutations in the type I collagen genes. Autosomal recessive mutations in a number of genes have also been described, including the BMP1 gene that encodes the mammalian Tolloid (mTLD) and its shorter isoform bone morphogenic protein‐1 (BMP1). To date, less than 20 individuals with OI have been identified with BMP1 mutations, with skeletal phenotypes ranging from mild to severe and progressively deforming. In the majority of patients, bone fragility was associated with increased bone mineral density (BMD); however, the full range of phenotypes associated with BMP1 remains unclear. Here, we describe three children with mutations in BMP1 associated with a highly variable phenotype: a sibship homozygous for the c.2188delC mutation that affects only the shorter BMP1 isoform and a further patient who is compound heterozygous for a c.1293C>G nonsense mutation and a c.1148G>A missense mutation in the CUB1 domain. These individuals had recurrent fractures from early childhood, are hypermobile and have no evidence of dentinogenesis imperfecta. The homozygous siblings with OI had normal areal BMD by dual energy X‐ray absorptiometry whereas the third patient presented with a high bone mass phenotype. Intravenous bisphosphonate therapy was started in all patients, but discontinued in two patients and reduced in another due to concerns about increasing bone stiffness leading to chalk‐stick fractures. Given the association of BMP1‐related OI with very high bone material density, concerns remain whether anti‐resorptive therapy is indicated in this ultra‐rare form of OI.© 2016 Wiley Periodicals, Inc.

Prevention and treatment of nutritional rickets.

Nutritional rickets continues to be a significant health problem for children worldwide with recent evidence of increasing incidence in many developed countries. It is due to vitamin D deficiency and/or inadequate dietary calcium intake with variation in the relative contributions of each of these dependant on environmental factors such a dietary intake and sunlight exposure. Key to the prevention of rickets is ensuring that pregnant women and their infants receive vitamin D supplementation with good evidence from randomised controlled trials that infants who receive 400iu daily can achieve levels of 25 hydroxyvitamin D of >50nmol/l. However, public health implementation of daily supplementation is more challenging with a need to revisit food fortification strategies to ensure optimal vitamin D status of the population. Treatment of nutritional rickets has traditionally been with vitamin D2 or D3, often given as a daily oral dose for several weeks until biochemical and radiological evidence of healing. However, other treatment regimes with single or intermittent high doses have also proved to be effective. It is now recognised that oral calcium either as dietary intake or supplements should be routinely used in conjunction with vitamin D for treatment.

The effect of whole body vibration training on bone and muscle function in children with osteogenesis imperfecta

ContextnOsteogenesis imperfecta (OI) is associated with reduced muscle size, dynamic muscle function, and mobility.nnnObjectivenTo assess the effect of whole body vibration (WBV) on bone density and geometry, muscle size and function, mobility, and balance in children with OI.nnnDesignnRandomized controlled pilot trial.nnnSettingnTertiary pediatric research center.nnnParticipantsnTwenty-four children (5 to 16 years) with OI types 1, 4, and limited mobility [Child Health Assessment Questionnaire (CHAQ) score ≥ 0.13] recruited in sex- and pubertal stage-matched pairs. Incident fractures in two boys (WBV arm) led to exclusion of two prepubertal pairs.nnnInterventionnFive months of WBV training (3 × 3 minutes twice daily) or regular care.nnnMain Outcome MeasuresnBone and muscle variables measured by dual-energy X-ray absorptiometry (spine, hip, total body) and peripheral quantitative computed tomography (tibia). Mobility assessed by 6-minute walk tests and CHAQ; dynamic muscle function by mechanography.nnnResultsnAll participants had reduced walking distances and muscle function (P < 0.001). Body mass index z score was associated with higher CHAQ scores (ρ + 0.552; P = 0.005) and lower walking and two-leg jumping performance (ρ - 0.405 to -0.654, P < 0.05). The WBV and control groups did not differ in the 5-month changes in bone. Total lean mass increased more in the WBV group [+1119 g (+224 to +1744)] compared with controls [+635 g (-951 to +1006)], P = 0.01, without improving mobility, muscle function, or balance.nnnConclusionsnThe increase in lean mass without changes in muscle function or bone mass suggests reduced biomechanical responsiveness of the muscle-bone unit in children with OI.

Biochemical Markers of Bone Metabolism

Publisher Summary This chapter reviews the clinical areas of interest, the possible applications, and limitations of using markers in the pediatric setting. Biochemical markers of bone metabolism are compounds that are released from bone tissue into the circulation and can be quantified in serum or urine samples. In adults, bone turnover markers mainly represent bone remodeling and are commonly used as independent predictors of the risk of osteoporosis and fractures, to monitor antiresorptive therapy and also have a promising role in metastatic bone disease. In children, these markers are released into the circulation during three different physiological processes: growth in bone length (bone elongation); growth in bone width (bone modeling by periosteal expansion); and bone remodeling (turnover). All bone markers measured in children reflect the sum of these three processes.

Hypopituitarism in children with cerebral palsy

Poor growth and delayed puberty in children with cerebral palsy is frequently felt to be related to malnutrition. Although growth hormone deficiency is commonly described in these children, multiple pituitary hormone deficiency (MPHD) has not been previously reported. We present a series of four children with cerebral palsy who were born before 29u2005weeks gestation who were referred to the regional endocrinology service, three for delayed puberty and one for short stature, in whom investigations identified MPHD. All patients had a height well below −2 standard deviation score (2nd centile) at presentation and three who had MRI scans had an ectopic posterior pituitary gland. We therefore recommend that the possibility of MPHD should be considered in all children with cerebral palsy and poor growth or delayed puberty. Early diagnosis and treatment is essential to maximise growth and prevent associated morbidity and mortality.

Loss of Functional Osteoprotegerin: More Than a Skeletal Problem.

IntroductionnJuvenile Pagets disease (JPD), an ultra-rare, debilitating bone disease due to loss of functional osteoprotegerin (OPG), is caused by recessive mutations in TNFRFSF11B. A genotype-phenotype correlation spanning from mild to very severe forms is described.nnnAimnThis study aimed to describe the complexity of the human phenotype of OPG deficiency in more detail and to investigate heterozygous mutation carriers for clinical signs of JPD.nnnPatientsnWe investigated 3 children with JPD from families of Turkish, German, and Pakistani descent and 19 family members (14 heterozygous).nnnResultsnA new disease-causing 4 bp-duplication in exon 1 was detected in the German patient, and a microdeletion including TNFRFSF11B in the Pakistani patient. Skeletal abnormalities in all affected children included bowing deformities and fractures, contractures, short stature and skull involvement. Complex malformation of the inner ear and vestibular structures (2 patients) resulted in early deafness. Patients were found to be growth hormone deficient (2), displayed nephrocalcinosis (1), and gross motor (3) and mental (1) retardation. Heterozygous family members displayed low OPG levels (12), elevated bone turnover markers (7), and osteopenia (6). Short stature (1), visual impairment (2), and hearing impairment (1) were also present.nnnConclusionnDiminished OPG levels cause complex changes affecting multiple organ systems, including pituitary function, in children with JPD and may cause osteopenia in heterozygous family members. Diagnostic and therapeutic measures should aim to address the complex phenotype.

Phenotypic Spectrum in Osteogenesis Imperfecta Due to Mutations in TMEM38B: Unraveling a Complex Cellular Defect

ContextnRecessive mutations in TMEM38B cause type XIV osteogenesis imperfecta (OI) by dysregulating intracellular calcium flux.nnnObjectivesnClinical and bone material phenotype description and osteoblast differentiation studies.nnnDesign and SettingnNatural history study in pediatric research centers.nnnPatientsnEight patients with type XIV OI.nnnMain Outcome MeasuresnClinical examinations included bone mineral density, radiographs, echocardiography, and muscle biopsy. Bone biopsy samples (n = 3) were analyzed using histomorphometry, quantitative backscattered electron microscopy, and Raman microspectroscopy. Cellular differentiation studies were performed on proband and control osteoblasts and normal murine osteoclasts.nnnResultsnType XIV OI clinical phenotype ranges from asymptomatic to severe. Previously unreported features include vertebral fractures, periosteal cloaking, coxa vara, and extraskeletal features (muscular hypotonia, cardiac abnormalities). Proband lumbar spine bone density z score was reduced [median -3.3 (range -4.77 to +0.1; n = 7)] and increased by +1.7 (1.17 to 3.0; n = 3) following bisphosphonate therapy. TMEM38B mutant bone has reduced trabecular bone volume, osteoblast, and particularly osteoclast numbers, with >80% reduction in bone resorption. Bone matrix mineralization is normal and nanoporosity low. We demonstrate a complex osteoblast differentiation defect with decreased expression of early markers and increased expression of late and mineralization-related markers. Predominance of trimeric intracellular cation channel type B over type A expression in murine osteoclasts supports an intrinsic osteoclast defect underlying low bone turnover.nnnConclusionsnOI type XIV has a bone histology, matrix mineralization, and osteoblast differentiation pattern that is distinct from OI with collagen defects. Probands are responsive to bisphosphonates and some show muscular and cardiovascular features possibly related to intracellular calcium flux abnormalities.