Publications by authors named "Andrew Biggin"

30 Publications

  • Page 1 of 1

L-carnitine supplementation for muscle weakness and fatigue in children with neurofibromatosis type 1: A Phase 2a clinical trial.

Am J Med Genet A 2021 Jun 21. Epub 2021 Jun 21.

Orthopaedic Research & Biotechnology, The Children's Hospital at Westmead, Sydney, New South Wales, Australia.

Reduced muscle tone, muscle weakness, and physical fatigue can impact considerably on quality of life for children with neurofibromatosis type 1 (NF1). Human muscle biopsies and mouse models of NF1 deficiency in muscle show intramyocellular lipid accumulation, and preclinical data have indicated that L-carnitine supplementation can ameliorate this phenotype. The aim of this study is to examine whether daily L-carnitine supplementation is safe and feasible, and will improve muscle strength and reduce fatigue in children with NF1. A 12-week Phase 2a trial was conducted using 1000 mg daily oral levocarnitine tartrate supplementation. Recruited children were between 8 and 12 years old with a clinical diagnosis of NF1, history of muscle weakness and fatigue, and naïve to L-carnitine. Primary outcomes were safety (self-reporting, biochemical testing) and compliance. Secondary outcomes included plasma acylcarnitine profiles, functional measures (muscle strength, long jump, handwriting speed, 6-minute-walk test [6MWT]), and parent-reported questionnaires (PedsQL™, CBCL/6-18). Six children completed the trial with no self-reported adverse events. Biochemical tests for kidney and liver function were normal, and the average compliance was 95%. Plasma acylcarnitine levels were low, but within a range not clinically linked to carnitine deficiency. For strength measures, there was a mean 53% increase in dorsiflexion strength (95% confidence interval [CI] 8.89-60.75; p = 0.02) and mean 66% increase in plantarflexion strength (95% CI 12.99-134.1; p = 0.03). In terms of muscle performance, there was a mean 10% increase in long jump distance (95% CI 2.97-16.03; p = 0.01) and 6MWT distance (95% CI 5.88-75.45; p = 0.03). Comparison with the 1000 Norms Project data showed a significant improvement in Z-score for all of these measures. Parent reports showed no negative impact on quality of life, and the perceived benefits led to the majority of individuals remaining on L-carnitine after the study. Twelve weeks of L-carnitine supplementation is safe and feasible in children with NF1, and a Phase 3 trial should confirm the efficacy of treatment.
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http://dx.doi.org/10.1002/ajmg.a.62392DOI Listing
June 2021

Magnetic resonance imaging pattern recognition in childhood bilateral basal ganglia disorders.

Brain Commun 2020 26;2(2):fcaa178. Epub 2020 Oct 26.

Kids Neuroscience Centre, The Children's Hospital at Westmead, Westmead, NSW 2145, Australia.

Bilateral basal ganglia abnormalities on MRI are observed in a wide variety of childhood disorders. MRI pattern recognition can enable rationalization of investigations and also complement clinical and molecular findings, particularly confirming genomic findings and also enabling new gene discovery. A pattern recognition approach in children with bilateral basal ganglia abnormalities on brain MRI was undertaken in this international multicentre cohort study. Three hundred and five MRI scans belonging to 201 children with 34 different disorders were rated using a standard radiological scoring proforma. In addition, literature review on MRI patterns was undertaken in these 34 disorders and 59 additional disorders reported with bilateral basal ganglia MRI abnormalities. Cluster analysis on first MRI findings from the study cohort grouped them into four clusters: Cluster 1-T-weighted hyperintensities in the putamen; Cluster 2-T-weighted hyperintensities or increased MRI susceptibility in the globus pallidus; Cluster 3-T-weighted hyperintensities in the globus pallidus, brainstem and cerebellum with diffusion restriction; Cluster 4-T-weighted hyperintensities in the basal ganglia. The 34 diagnostic categories included in this study showed dominant clustering in one of the above four clusters. Inflammatory disorders grouped together in Cluster 1. Mitochondrial and other neurometabolic disorders were distributed across clusters 1, 2 and 3, according to lesions dominantly affecting the (Cluster 1: glutaric aciduria type 1, propionic acidaemia, 3-methylglutaconic aciduria with deafness, encephalopathy and Leigh-like syndrome and thiamine responsive basal ganglia disease associated with ), pallidum (Cluster 2: methylmalonic acidaemia, Kearns Sayre syndrome, pyruvate dehydrogenase complex deficiency and succinic semialdehyde dehydrogenase deficiency) or pallidum, brainstem and cerebellum (Cluster 3: vigabatrin toxicity, Krabbe disease). The Cluster 4 pattern was exemplified by distinct T-weighted hyperintensities in the basal ganglia and other brain regions in genetically determined hypermanganesemia due to and . Within the clusters, distinctive basal ganglia MRI patterns were noted in acquired disorders such as cerebral palsy due to hypoxic ischaemic encephalopathy in full-term babies, kernicterus and vigabatrin toxicity and in rare genetic disorders such as 3-methylglutaconic aciduria with deafness, encephalopathy and Leigh-like syndrome, thiamine responsive basal ganglia disease, pantothenate kinase-associated neurodegeneration, and hypermanganesemia. Integrated findings from the study cohort and literature review were used to propose a diagnostic algorithm to approach bilateral basal ganglia abnormalities on MRI. After integrating clinical summaries and MRI findings from the literature review, we developed a prototypic decision-making electronic tool to be tested using further cohorts and clinical practice.
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http://dx.doi.org/10.1093/braincomms/fcaa178DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7891249PMC
October 2020

Patient-Reported Outcomes from a Randomized, Active-Controlled, Open-Label, Phase 3 Trial of Burosumab Versus Conventional Therapy in Children with X-Linked Hypophosphatemia.

Calcif Tissue Int 2021 05 23;108(5):622-633. Epub 2021 Jan 23.

Department of Medicine and Department of Pediatrics, Indiana University School of Medicine, Indianapolis, IN, USA.

Changing to burosumab, a monoclonal antibody targeting fibroblast growth factor 23, significantly improved phosphorus homeostasis, rickets, lower-extremity deformities, mobility, and growth versus continuing oral phosphate and active vitamin D (conventional therapy) in a randomized, open-label, phase 3 trial involving children aged 1-12 years with X-linked hypophosphatemia. Patients were randomized (1:1) to subcutaneous burosumab or to continue conventional therapy. We present patient-reported outcomes (PROs) from this trial for children aged ≥ 5 years at screening (n = 35), using a Patient-Reported Outcomes Measurement Information System (PROMIS) questionnaire and SF-10 Health Survey for Children. PROMIS pain interference, physical function mobility, and fatigue scores improved from baseline with burosumab at weeks 40 and 64, but changed little with continued conventional therapy. Pain interference scores differed significantly between groups at week 40 (- 5.02, 95% CI - 9.29 to - 0.75; p = 0.0212) but not at week 64. Between-group differences were not significant at either week for physical function mobility or fatigue. Reductions in PROMIS pain interference and fatigue scores from baseline were clinically meaningful with burosumab at weeks 40 and 64 but not with conventional therapy. SF-10 physical health scores (PHS-10) improved significantly with burosumab at week 40 (least-squares mean [standard error] + 5.98 [1.79]; p = 0.0008) and week 64 (+ 5.93 [1.88]; p = 0.0016) but not with conventional therapy (between-treatment differences were nonsignificant). In conclusion, changing to burosumab improved PRO measures, with statistically significant differences in PROMIS pain interference at week 40 versus continuing with conventional therapy and in PHS-10 at weeks 40 and 64 versus baseline.Trial registration: ClinicalTrials.gov NCT02915705.
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http://dx.doi.org/10.1007/s00223-020-00797-xDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8064984PMC
May 2021

Quantitative estimates of average geomagnetic axial dipole dominance in deep geological time.

Nat Commun 2020 11 30;11(1):6100. Epub 2020 Nov 30.

Centre for Earth Evolution and Dynamics, University of Oslo, Sem Saelands vei 2A, 0315, Oslo, Norway.

A defining characteristic of the recent geomagnetic field is its dominant axial dipole which provides its navigational utility and dictates the shape of the magnetosphere. Going back through time, much less is known about the degree of axial dipole dominance. Here we use a substantial and diverse set of 3D numerical dynamo simulations and recent observation-based field models to derive a power law relationship between the angular dispersion of virtual geomagnetic poles at the equator and the median axial dipole dominance measured at Earth's surface. Applying this relation to published estimates of equatorial angular dispersion implies that geomagnetic axial dipole dominance averaged over 10-10 years has remained moderately high and stable through large parts of geological time. This provides an observational constraint to future studies of the geodynamo and palaeomagnetosphere. It also provides some reassurance as to the reliability of palaeogeographical reconstructions provided by palaeomagnetism.
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http://dx.doi.org/10.1038/s41467-020-19794-7DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7704635PMC
November 2020

High Bone Mineral Density Osteogenesis Imperfecta in a Family with a Novel Pathogenic Variant in COL1A2.

Horm Res Paediatr 2020 11;93(4):263-271. Epub 2020 Sep 11.

Institute of Endocrinology and Diabetes, The Children's Hospital at Westmead, Westmead, New South Wales, Australia.

Osteogenesis imperfecta (OI) is a heterogenous group of heritable bone dysplasias characterized by bone fragility, typically low bone mass, joint laxity, easy bruising, and variable short stature. Classical OI is caused by autosomal dominant pathogenic variants in COL1A1 or COL1A2 that result in either reduced production of normal type 1 collagen or structurally abnormal collagen molecules. Pathogenic variants in these genes generally result in low bone mass. Here, we report a family that had 2 affected individuals who presented with minimal trauma fractures and were found to have elevated bone mineral density (BMD) and a previously unreported variant in COL1A2 c.3356C>T p.(Ala1119Val). We report the change in BMD using dual-energy X-ray and peripheral quantitative computed tomography over a 2.3-year period in the proband. This case report highlights the importance of BMD studies and genetic testing in the diagnostic process for brittle bone disorders.
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http://dx.doi.org/10.1159/000510463DOI Listing
September 2020

Elevated paleomagnetic dispersion at Saint Helena suggests long-lived anomalous behavior in the South Atlantic.

Proc Natl Acad Sci U S A 2020 08 20;117(31):18258-18263. Epub 2020 Jul 20.

Geomagnetism Laboratory, Department of Earth, Ocean and Ecological Sciences, University of Liverpool, Liverpool L69 7ZE, United Kingdom.

Earth's magnetic field is presently characterized by a large and growing anomaly in the South Atlantic Ocean. The question of whether this region of Earth's surface is preferentially subject to enhanced geomagnetic variability on geological timescales has major implications for core dynamics, core-mantle interaction, and the possibility of an imminent magnetic polarity reversal. Here we present paleomagnetic data from Saint Helena, a volcanic island ideally suited for testing the hypothesis that geomagnetic field behavior is anomalous in the South Atlantic on timescales of millions of years. Our results, supported by positive baked contact and reversal tests, produce a mean direction approximating that expected from a geocentric axial dipole for the interval 8 to 11 million years ago, but with very large associated directional dispersion. These findings indicate that, on geological timescales, geomagnetic secular variation is persistently enhanced in the vicinity of Saint Helena. This, in turn, supports the South Atlantic as a locus of unusual geomagnetic behavior arising from core-mantle interaction, while also appearing to reduce the likelihood that the present-day regional anomaly is a precursor to a global polarity reversal.
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http://dx.doi.org/10.1073/pnas.2001217117DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7414061PMC
August 2020

Global consensus on nutritional rickets: Implications for Australia.

J Paediatr Child Health 2020 06;56(6):841-846

Institute of Endocrinology and Diabetes, Children's Hospital Westmead, Sydney, New South Wales, Australia.

In 2016, a global consensus on the prevention, diagnosis and management of nutritional rickets was published. The bone and mineral working group of the Australasian Paediatric Endocrine Group provides a summary and highlights differences to previous Australian and New Zealand (ANZ) guidelines on vitamin D deficiency and their implications for clinicians. Key points are: (i) The International Consensus document is focused on nutritional rickets, whereas the ANZ guidelines were focused on vitamin D deficiency. (ii) Definitions for the interpretation of 25-hydroxy vitamin D (25OHD) levels do not differ between statements. (iii) The global consensus recommends that routine 25OHD screening should not be performed in healthy children and recommendations for vitamin D supplementation are not based solely on 25OHD levels. The Australasian Paediatric Endocrine Group bone and mineral working group supports that screening for vitamin D deficiency should be restricted to populations at risk. (iv) Recommendations from the global consensus for vitamin D dosages for the therapy of nutritional rickets (diagnosed based on history, physical examination, biochemical testing and a confirmation by X-rays) are higher than in ANZ publications. (v) The global consensus recommends the implementation of public health strategies such as universal supplementation with vitamin D from birth to 1 year of age and food fortification. We conclude that updated global recommendations for therapy of nutritional rickets complement previously published position statements for Australia and New Zealand. Screening, management and the implementation of public health strategies need to be further explored for Australia.
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http://dx.doi.org/10.1111/jpc.14941DOI Listing
June 2020

Clinical Evidence for the Benefits of Burosumab Therapy for X-Linked Hypophosphatemia (XLH) and Other Conditions in Adults and Children.

Front Endocrinol (Lausanne) 2020 28;11:338. Epub 2020 May 28.

Discipline of Child and Adolescent Health, University of Sydney, Sydney, NSW, Australia.

Burosumab (KRN23) is an FGF23 neutralizing antibody that has been the subject of several recent clinical trials principally focused on the treatment of hypophosphatemic rickets in patients with X-linked hypophosphatemia (XLH). Since the first publications in 2014, these trials have demonstrated efficacy with minimal safety concerns in both adult and pediatric cohorts. These studies have used dose-escalation to establish a dosing regimen that is well-tolerated in clinical use. This review summarizes the clinical trial data with respect to burosumab treatment in adults and children as well as noting several clinical trials currently underway. While burosumab appears transformative for the treatment of XLH, long term follow-up studies would be required to allay concerns over the potential for nephrocalcinosis and cardiac calcification. While these do not appear to be problematic in current trials, the effects of chronic or lifelong treatment have yet to be established.
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http://dx.doi.org/10.3389/fendo.2020.00338DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7271822PMC
May 2021

Positive impacts of changes to a tertiary hospital after-hours endocrine and diabetes on-call service.

J Paediatr Child Health 2020 05 17;56(5):742-745. Epub 2019 Dec 17.

Institute of Endocrinology and Diabetes, The Children's Hospital Westmead, Sydney, New South Wales, Australia.

Aim: To examine the impact of changes to the endocrine/diabetes after-hours service model of care at a major tertiary children's hospital in Australia. The model aimed to enhance the independence of families and reduce dependency on after-hours calls to health professionals.

Methods: The after-hours activity was captured prospectively using an iPad with a customised FileMaker database. Data were collected for 9 months prior to and for 8 months after the implementation of a modified model of service. Questionnaires gathered information from endocrine junior medical officers (JMOs) and other hospital staff. Data on emergency department visits were analysed for presentations before and after the implementation of the service changes.

Results: Changes to the after-hours service resulted in a significant reduction in median calls from 9 (range 0-39) to 2 (range 0-7) per shift. The number of shifts with no calls increased from 2 to 24% and the number of shifts with <3 calls increased from 8 to 60%. Disturbed nights (calls between 10 pm and 6 am) decreased from 75 to 29%. Junior medical officer experience was positive and there was no perceivable increase in workload from in-hospital staff. The number of endocrine patients presenting to the emergency department did not change significantly following the implementation of the new after-hours service.

Conclusion: This is the only Australian study to prospectively gather accurate on-call data in order to elucidate the impact of changing a hospital's after-hours endocrine/diabetes service to a model that enhanced family empowerment and independence. Historical 24-h on-call service models are not indispensable, and changes can improve sustainability without compromising patient care.
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http://dx.doi.org/10.1111/jpc.14722DOI Listing
May 2020

FGF23, Hypophosphatemia, and Emerging Treatments.

JBMR Plus 2019 Aug 13;3(8):e10190. Epub 2019 May 13.

The University of Sydney Children's Hospital Westmead Clinical School, University of Sydney Sydney Australia.

FGF23 is an important hormonal regulator of phosphate homeostasis. Together with its co-receptor Klotho, it modulates phosphate reabsorption and both 1α-hydroxylation and 24-hydroxylation in the renal proximal tubules. The most common FGF23-mediated hypophosphatemia is X-linked hypophosphatemia (XLH), caused by mutations in the gene. FGF23-mediated forms of hypophosphatemia are characterized by phosphaturia and low or low-normal calcitriol concentrations, and unlike nutritional rickets, these cannot be cured with nutritional vitamin D supplementation. Autosomal dominant and autosomal recessive forms of FGF23-mediated hypophosphatemias show a similar pathophysiology, despite a variety of different underlying genetic causes. An excess of FGF23 activity has also been associated with a number of other conditions causing hypophosphatemia, including tumor-induced osteomalacia, fibrous dysplasia of the bone, and cutaneous skeletal hypophosphatemia syndrome. Historically phosphate supplementation and therapy using analogs of highly active vitamin D (eg, calcitriol, alfacalcidol, paricalcitol, eldecalcitol) have been used to manage conditions involving hypophosphatemia; however, recently a neutralizing antibody for FGF23 (burosumab) has emerged as a promising treatment agent for FGF23-mediated disorders. This review discusses the progression of clinical trials for burosumab for the treatment of XLH and its recent availability for clinical use. Burosumab may have potential for treating other conditions associated with FGF23 overactivity, but these are not yet supported by trial data. © 2019 The Authors. published by Wiley Periodicals, Inc. on behalf of American Society for Bone and Mineral Research.
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http://dx.doi.org/10.1002/jbm4.10190DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6715782PMC
August 2019

Glibenclamide treatment in a Cantú syndrome patient with a pathogenic ABCC9 gain-of-function variant: Initial experience.

Am J Med Genet A 2019 08 7;179(8):1585-1590. Epub 2019 Jun 7.

Center for the Investigation of Membrane Excitability Diseases, Washington University School of Medicine, St. Louis, Missouri.

Cantú syndrome (CS), characterized by hypertrichosis, distinctive facial features, and complex cardiovascular abnormalities, is caused by pathogenic variants in ABCC9 and KCNJ8 genes. These genes encode gain-of-function mutations in the regulatory (SUR2) and pore-forming (Kir6.1) subunits of K channels, respectively, suggesting that channel-blocking sulfonylureas could be a viable therapy. Here we report a neonate with CS, carrying a heterozygous ABCC9 variant (c.3347G>A, p.Arg1116His), born prematurely at 32 weeks gestation. Initial echocardiogram revealed a large patent ductus arteriosus (PDA), and high pulmonary pressures with enlarged right ventricle. He initially received surfactant and continuous positive airway pressure ventilation and was invasively ventilated for 4 weeks, until PDA ligation. After surgery, he still had ongoing bilevel positive airway pressure (BiPAP) requirement, but was subsequently weaned to nocturnal BiPAP. He was treated for pulmonary hypertension with Sildenafil, but failed to make further clinical improvement. A therapeutic glibenclamide trial was commenced in week 11 (initial dose of 0.05 mg kg day in two divided doses). After 1 week of treatment, he began to tolerate time off BiPAP when awake, and edema improved. Glibenclamide was well tolerated, and the dose was slowly increased to 0.15 mg kg day over the next 12 weeks. Mild transient hypoglycemia was observed, but there was no cardiovascular dysfunction. Confirmation of therapeutic benefit will require studies of more CS patients but, based on this limited experience, consideration should be given to glibenclamide as CS therapy, although problems associated with prematurity, and complications of hypoglycemia, might limit outcome in critically ill neonates with CS.
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http://dx.doi.org/10.1002/ajmg.a.61200DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6899598PMC
August 2019

Safety and effectiveness of stoss therapy in children with vitamin D deficiency.

J Paediatr Child Health 2020 Jan 28;56(1):81-89. Epub 2019 May 28.

Institute of Endocrinology and Diabetes, The Children's Hospital at Westmead, Children's Hospital Westmead Clinical School, University of Sydney, Sydney, New South Wales, Australia.

Aim: Paediatric vitamin D (25-hydroxyvitamin D (25OHD)) deficiency can lead to nutritional rickets and extra-skeletal complications. Compliance with daily therapy can be difficult, making high-dose, short-term vitamin D (stoss) therapy attractive to correct vitamin D deficiency. We compared the effectiveness and safety of standard versus stoss therapy in treating childhood 25OHD deficiency.

Methods: Children aged 2-16 years with 25OHD <50 nmol/L were randomised to either standard (5000 IU daily for 80 days) or stoss (100 000 IU weekly for 4 weeks) cholecalciferol. Participants underwent an evaluation of effectiveness and safety. The 25OHD level, random spot calcium: creatinine ratio (Ca:Cr) and compliance were measured at 12 weeks.

Results: A total of 151 children were enrolled in the study (68 standard and 83 stoss), median age 9 years (inter-quartile range (IQR): 6-12 years). Baseline 25OHD levels were 26 nmol/L (IQR: 19-35 nmol/L) and 32 nmol/L (IQR: 24-39 nmol/L) in the standard and stoss groups, respectively. At 12 weeks, the median 25OHD level was significantly greater in the standard versus stoss group (81 vs. 67 nmol/L; P = 0.005); however, >80% of participants in both groups achieved sufficiency (25OHD > 50 nmol/L) and had normal urinary Ca:Cr, with no significant difference seen between groups. Compliance was similar in the two groups.

Conclusions: Compared to stoss, standard therapy achieved higher 25OHD levels at 12 weeks; however, in both groups, there was a similar proportion of participants who achieved 25OHD sufficiency, with no evidence of toxicity. Unlike other studies, simplifying the treatment regimen did not improve compliance. These results support stoss therapy as an effective and safe alternative therapy for the treatment of paediatric vitamin D deficiency.
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http://dx.doi.org/10.1111/jpc.14497DOI Listing
January 2020

Burosumab versus conventional therapy in children with X-linked hypophosphataemia: a randomised, active-controlled, open-label, phase 3 trial.

Lancet 2019 06 16;393(10189):2416-2427. Epub 2019 May 16.

Department of Pediatrics, University of California, San Francisco, San Francisco, CA, USA.

Background: X-linked hypophosphataemia in children is characterised by elevated serum concentrations of fibroblast growth factor 23 (FGF23), hypophosphataemia, rickets, lower extremity bowing, and growth impairment. We compared the efficacy and safety of continuing conventional therapy, consisting of oral phosphate and active vitamin D, versus switching to burosumab, a fully human monoclonal antibody against FGF23, in paediatric X-linked hypophosphataemia.

Methods: In this randomised, active-controlled, open-label, phase 3 trial at 16 clinical sites, we enrolled children with X-linked hypophosphataemia aged 1-12 years. Key eligibility criteria were a total Thacher rickets severity score of at least 2·0, fasting serum phosphorus lower than 0·97 mmol/L (3·0 mg/dL), confirmed PHEX (phosphate-regulating endopeptidase homolog, X-linked) mutation or variant of unknown significance in the patient or a family member with appropriate X-linked dominant inheritance, and receipt of conventional therapy for at least 6 consecutive months for children younger than 3 years or at least 12 consecutive months for children older than 3 years. Eligible patients were randomly assigned (1:1) to receive either subcutaneous burosumab starting at 0·8 mg/kg every 2 weeks (burosumab group) or conventional therapy prescribed by investigators (conventional therapy group). Both interventions lasted 64 weeks. The primary endpoint was change in rickets severity at week 40, assessed by the Radiographic Global Impression of Change global score. All patients who received at least one dose of treatment were included in the primary and safety analyses. The trial is registered with ClinicalTrials.gov, number NCT02915705.

Findings: Recruitment took place between Aug 3, 2016, and May 8, 2017. Of 122 patients assessed, 61 were enrolled. Of these, 32 (18 girls, 14 boys) were randomly assigned to continue receiving conventional therapy and 29 (16 girls, 13 boys) to receive burosumab. For the primary endpoint at week 40, patients in the burosumab group had significantly greater improvement in Radiographic Global Impression of Change global score than did patients in the conventional therapy group (least squares mean +1·9 [SE 0·1] with burosumab vs +0·8 [0·1] with conventional therapy; difference 1·1, 95% CI 0·8-1·5; p<0·0001). Treatment-emergent adverse events considered possibly, probably, or definitely related to treatment by the investigator occurred more frequently with burosumab (17 [59%] of 29 patients in the burosumab group vs seven [22%] of 32 patients in the conventional therapy group). Three serious adverse events occurred in each group, all considered unrelated to treatment and resolved.

Interpretation: Significantly greater clinical improvements were shown in rickets severity, growth, and biochemistries among children with X-linked hypophosphataemia treated with burosumab compared with those continuing conventional therapy.

Funding: Ultragenyx Pharmaceutical and Kyowa Kirin International.
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http://dx.doi.org/10.1016/S0140-6736(19)30654-3DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7179969PMC
June 2019

Long-term Outcomes of Adolescent Anorexia Nervosa on Bone.

J Adolesc Health 2019 03 11;64(3):305-310. Epub 2018 Dec 11.

Department of Endocrinology, The Children's Hospital at Westmead, Westmead, New South Wales, Australia; Discipline of Paediatrics & Child Health, University of Sydney, Sydney, New South Wales, Australia. Electronic address:

Purpose: Anorexia nervosa (AN) is a chronic and life-threatening eating disorder that can have a considerable negative impact on the growing skeleton. We hypothesized that the long-term impact on bone health may persist even after normalization of body weight.

Methods: 41 females (mean age 21.2 ± 2.9 years) with a history of adolescent-onset AN attended a follow-up bone health assessment at 5 years (T5, n = 28) or 10 years (T10, n = 13) after their first AN-related hospital admission. Assessment included dual-energy x-ray absorptiometry measurements of the total body, lumbar spine, and proximal femur, peripheral quantitative computed tomography at the radius and tibia, anthropometric measurements, serum biochemistry, fracture history, and a patient questionnaire.

Results: A recovery in body weight and BMI was seen for both the T5 and T10 cohorts (BMI at intake 16.6, BMI at T5-T10 21.2-21.3). Dual-energy x-ray absorptiometry body composition indicated a recovery of fat mass and lean tissue mass. Total BMD was unaffected, but reductions were seen at the femoral neck and arms. Peripheral quantitative computed tomography showed reduced trabecular and cortical bone in the radius, and cortical thinning in the tibia. AN patients showed a statistically significant reduction in measures of radiographic bone health at follow up, although not to a degree that necessitated clinical intervention. Serum insulin-like growth factor 1 was also positively correlated with total BMD and BMC measures. While fracture risk was not increased, a subset of participants (8%) showed multiple (>4) fractures.

Conclusion: A longitudinal study of adolescent AN showed persisting negative effects on bone health.
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http://dx.doi.org/10.1016/j.jadohealth.2018.07.025DOI Listing
March 2019

A 21st century plague of biblical proportions.

Authors:
Andrew Biggin

J Paediatr Child Health 2018 12 9;54(12):1292-1293. Epub 2018 Sep 9.

Faculty of Medicine and Health, University of Sydney Children's Hospital Westmead Clinical School, Sydney, New South Wales, Australia.

Modern medicine has eradicated smallpox, contained polio and is making significant advances in personalised/genetic medicine. However, we are facing a pandemic of apocalyptic proportions, and there is currently no vaccine or United Nations Charter to help address this issue. Following its insidious spread in the 1980s, the full impact of this phenomenon on civilisation has not been fully appreciated. It has slipped under the radar of the International Classification of Diseases (ICD-10) and Diagnostic and Statistical Manual of Mental Disorders (DSM-5) classification systems. We all know someone who is affected by this condition, and society is struggling to cope with the acute and chronic morbidity that has ensued. I am, of course, referring to the problem of the workplace email. This article examines the problems associated with workplace email and aims to offer some strategies to help contain it.
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http://dx.doi.org/10.1111/jpc.14218DOI Listing
December 2018

Hemophagocytic Lymphohistiocytosis in Loeys-Dietz Syndrome.

J Clin Immunol 2018 04 9;38(3):234-236. Epub 2018 Mar 9.

Discipline of Child and Adolescent Health, University of Sydney, Westmead, NSW, 2145, Australia.

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http://dx.doi.org/10.1007/s10875-018-0484-0DOI Listing
April 2018

Consensus guidelines on the use of bisphosphonate therapy in children and adolescents.

J Paediatr Child Health 2018 Mar;54(3):223-233

Institute of Endocrinology and Diabetes, Children's Hospital at Westmead, Sydney, New South Wales, Australia.

Bisphosphonate therapy is the mainstay of pharmacological intervention in young people with skeletal fragility. The evidence of its use in a variety of conditions remains limited despite over three decades of clinical experience. On behalf of the Australasian Paediatric Endocrine Group, this evidence-based consensus guideline presents recommendations and discusses the graded evidence (using the GRADE system) for these recommendations. Primary bone fragility disorders such as osteogenesis imperfecta are considered separately from osteoporosis secondary to other clinical conditions (such as cerebral palsy, Duchenne muscular dystrophy). The use of bisphosphonates in non-fragility conditions, such as fibrous dysplasia, avascular necrosis, bone cysts and hypercalcaemia, is also discussed. While these guidelines provide an evidence-based approach where possible, further research is required in all clinical applications in order to strengthen the recommendations made.
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http://dx.doi.org/10.1111/jpc.13768DOI Listing
March 2018

Novel variant in Sp7/Osx associated with recessive osteogenesis imperfecta with bone fragility and hearing impairment.

Bone 2018 05 31;110:66-75. Epub 2018 Jan 31.

Institute of Endocrinology and Diabetes, The Children's Hospital at Westmead, Sydney, NSW, Australia; Discipline of Child & Adolescent Health, Sydney Medical School, University of Sydney, Sydney, NSW, Australia.

Osteogenesis imperfecta (OI) is a connective tissue disorder characterized by low bone density and recurrent fractures with a wide genotypic and phenotypic spectrum. Common features include short stature, opalescent teeth, blue sclerae and hearing impairment. The majority (>90%) of patients with OI have autosomal dominant variants in COL1A1/COL1A2, which lead to defects in type 1 collagen. More recently, numerous recessive variants involving other genes have also been identified. Sp7/Osx gene, is a protein coding gene that encodes a zinc finger transcription factor, osterix, which is a member of the Sp subfamily of sequence-specific DNA-binding proteins. Osterix is expressed primarily by osteoblasts and has been shown to be vital for bone formation and bone homeostasis by promoting osteoblast differentiation and maturation. In animal models, Sp7/Osx has also been shown to regulate biomineralization of otoliths, calcium carbonate structures found in the inner ear of vertebrates. Until recently, only one report of a boy with an Sp7/Osx pathogenic variant presenting with bone fragility, limb deformities and normal hearing has been described in the literature. We have identified a novel Sp7/Osx variant in another sibship that presented with osteoporosis, low-trauma fractures and short stature. Progressive moderate-to-severe and severe-to-profound hearing loss secondary to otospongiosis and poor mineralization of ossicles and petrous temporal bone was also noted in two of the siblings. A homozygous pathogenic variant in exon 2 of the Sp7/Osx gene was found in all affected relatives; c.946C>T (p.Arg316Cys). Bone biopsies in the proband and his male sibling revealed significant cortical porosity and high trabecular bone turnover. This is the second report to describe children with OI associated with an Sp7/Osx variant. However, it is the first to describe the bone histomorphometry associated with this disorder and identifies a significant hearing loss as a potential feature in this OI subtype. Early audiology screening in these children is therefore warranted.
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http://dx.doi.org/10.1016/j.bone.2018.01.031DOI Listing
May 2018

Advancing Precambrian palaeomagnetism with the PALEOMAGIA and PINT() databases.

Sci Data 2017 05 23;4:170068. Epub 2017 May 23.

Scripps Institution of Oceanography, University of California, San Diego, 8635 Kennel Way, La Jolla, California 92093-0220, USA.

State-of-the-art measurements of the direction and intensity of Earth's ancient magnetic field have made important contributions to our understanding of the geology and palaeogeography of Precambrian Earth. The PALEOMAGIA and PINT() databases provide thorough public collections of important palaeomagnetic data of this kind. They comprise more than 4,100 observations in total and have been essential in supporting our international collaborative efforts to understand Earth's magnetic history on a timescale far longer than that of the present Phanerozoic Eon. Here, we provide an overview of the technical structure and applications of both databases, paying particular attention to recent improvements and discoveries.
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http://dx.doi.org/10.1038/sdata.2017.68DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5441291PMC
May 2017

A Practical Approach to Children with Recurrent Fractures.

Endocr Dev 2015 12;28:210-25. Epub 2015 Jun 12.

Institute of Endocrinology and Diabetes, The Children's Hospital Westmead, Westmead, NSW, Australia.

As many as 50% of children will sustain a fracture before 18 years of age, and up to 20% will have two or more fractures. A small proportion of children who experience multiple fractures have osteoporosis, either from a genetic bone disorder (primary osteoporosis) or secondary to another underlying medical condition (secondary osteoporosis). Fracture history, together with bone mineral density assessment and vertebral radiographs, help clinicians to identify children with osteoporosis. Its aetiology can usually be determined through the combination of a detailed medical history and physical examination, laboratory investigations to assess mineral homeostasis, evaluation of secondary causes of osteoporosis and genetic studies to identify the underlying cause of the disorder. Transiliac bone biopsy with histology and histomorphometry should not be overlooked as valuable tools for the investigation of a child with osteoporosis of uncertain aetiology. Optimal management of osteoporosis requires a multidisciplinary team to address physical activity, nutrition, pubertal progression, the management of any underlying medical condition, pharmacotherapy (bisphosphonates) and orthopaedic surgery. This chapter outlines an approach to the evaluation and treatment of children with recurrent fractures and describes three common scenarios involving infants, children with chronic illness and children without chronic illness.
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http://dx.doi.org/10.1159/000381047DOI Listing
November 2016

Homozygosity for frameshift mutations in XYLT2 result in a spondylo-ocular syndrome with bone fragility, cataracts, and hearing defects.

Am J Hum Genet 2015 Jun 28;96(6):971-8. Epub 2015 May 28.

Department of Physiological Sciences, Oklahoma State University, Stillwater, OK 74078, USA; Department of Cell Biology, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73126, USA. Electronic address:

Heparan and chondroitin/dermatan sulfated proteoglycans have a wide range of roles in cellular and tissue homeostasis including growth factor function, morphogen gradient formation, and co-receptor activity. Proteoglycan assembly initiates with a xylose monosaccharide covalently attached by either xylosyltransferase I or II. Three individuals from two families were found that exhibited similar phenotypes. The index case subjects were two brothers, individuals 1 and 2, who presented with osteoporosis, cataracts, sensorineural hearing loss, and mild learning defects. Whole exome sequence analyses showed that both individuals had a homozygous c.692dup mutation (GenBank: NM_022167.3) in the xylosyltransferase II locus (XYLT2) (MIM: 608125), causing reduced XYLT2 mRNA and low circulating xylosyltransferase (XylT) activity. In an unrelated boy (individual 3) from the second family, we noted low serum XylT activity. Sanger sequencing of XYLT2 in this individual revealed a c.520del mutation in exon 2 that resulted in a frameshift and premature stop codon (p.Ala174Profs(∗)35). Fibroblasts from individuals 1 and 2 showed a range of defects including reduced XylT activity, GAG incorporation of (35)SO4, and heparan sulfate proteoglycan assembly. These studies demonstrate that human XylT2 deficiency results in vertebral compression fractures, sensorineural hearing loss, eye defects, and heart defects, a phenotype that is similar to the autosomal-recessive disorder spondylo-ocular syndrome of unknown cause. This phenotype is different from what has been reported in individuals with other linker enzyme deficiencies. These studies illustrate that the cells of the lens, retina, heart muscle, inner ear, and bone are dependent on XylT2 for proteoglycan assembly in humans.
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http://dx.doi.org/10.1016/j.ajhg.2015.04.017DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4457947PMC
June 2015

The long-term effects of switching from active intravenous bisphosphonate treatment to low-dose maintenance therapy in children with osteogenesis imperfecta.

Horm Res Paediatr 2015 10;83(3):183-9. Epub 2015 Feb 10.

Institute of Endocrinology and Diabetes, Children's Hospital Westmead, Westmead, N.S.W., Australia.

Background/aims: Intravenous bisphosphonate therapy is the first-line treatment in moderate-to-severe osteogenesis imperfecta (OI), but there are varied treatment protocols with little data on long-term efficacy. This study evaluates the clinical outcomes when transitioning from active bisphosphonate treatment to maintenance therapy.

Methods: A retrospective review was conducted on 17 patients before treatment, following active treatment (zoledronate 0.05 mg/kg 6-monthly or pamidronate 6-9 mg/kg/year) and after establishment on maintenance treatment for more than 2 years (zoledronate 0.025 mg/kg 6-monthly or pamidronate <4 mg/kg/year).

Results: There was a significant reduction in mean fracture rate from 1.5 ± 1.1 fractures/year at baseline to 0.7 ± 0.7 fractures/year on active treatment. Z-scores for lumbar spine bone mineral density, bone mineral content, volumetric bone mineral density and bone mineral content for lean tissue mass increased during active treatment. These improvements were maintained during the period of maintenance treatment. Vertebral height improved in fractured thoracic vertebrae from pre-treatment to active therapy and improved further during maintenance treatment. Metacarpal cortical thickness and relative cortical area also increased over the treatment periods.

Conclusion: Maintenance intravenous bisphosphonate therapy preserved the beneficial effects of active treatment at the doses stated above. Further studies are required to determine the optimal bisphosphonate treatment regimen in the management of children with OI.
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http://dx.doi.org/10.1159/000369582DOI Listing
January 2016

Mutations in SLC34A3/NPT2c are associated with kidney stones and nephrocalcinosis.

J Am Soc Nephrol 2014 Oct 3;25(10):2366-75. Epub 2014 Apr 3.

Endocrine Unit, and

Compound heterozygous and homozygous (comp/hom) mutations in solute carrier family 34, member 3 (SLC34A3), the gene encoding the sodium (Na(+))-dependent phosphate cotransporter 2c (NPT2c), cause hereditary hypophosphatemic rickets with hypercalciuria (HHRH), a disorder characterized by renal phosphate wasting resulting in hypophosphatemia, correspondingly elevated 1,25(OH)2 vitamin D levels, hypercalciuria, and rickets/osteomalacia. Similar, albeit less severe, biochemical changes are observed in heterozygous (het) carriers and indistinguishable from those changes encountered in idiopathic hypercalciuria (IH). Here, we report a review of clinical and laboratory records of 133 individuals from 27 kindreds, including 5 previously unreported HHRH kindreds and two cases with IH, in which known and novel SLC34A3 mutations (c.1357delTTC [p.F453del]; c.G1369A [p.G457S]; c.367delC) were identified. Individuals with mutations affecting both SLC34A3 alleles had a significantly increased risk of kidney stone formation or medullary nephrocalcinosis, namely 46% compared with 6% observed in healthy family members carrying only the wild-type SLC34A3 allele (P=0.005) or 5.64% in the general population (P<0.001). Renal calcifications were also more frequent in het carriers (16%; P=0.003 compared with the general population) and were more likely to occur in comp/hom and het individuals with decreased serum phosphate (odds ratio [OR], 0.75, 95% confidence interval [95% CI], 0.59 to 0.96; P=0.02), decreased tubular reabsorption of phosphate (OR, 0.41; 95% CI, 0.23 to 0.72; P=0.002), and increased serum 1,25(OH)2 vitamin D (OR, 1.22; 95% CI, 1.05 to 1.41; P=0.008). Additional studies are needed to determine whether these biochemical parameters are independent of genotype and can guide therapy to prevent nephrocalcinosis, nephrolithiasis, and potentially, CKD.
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http://dx.doi.org/10.1681/ASN.2013101085DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4178443PMC
October 2014

Fracture during intravenous bisphosphonate treatment in a child with osteogenesis imperfecta: an argument for a more frequent, low-dose treatment regimen.

Horm Res Paediatr 2014 19;81(3):204-10. Epub 2013 Dec 19.

Institute of Endocrinology and Diabetes, The Sydney Children's Hospitals Network, Westmead, N.S.W., Australia.

Background/aims: Intravenous bisphosphonate therapy is the mainstay of medical treatment in osteogenesis imperfecta (OI) and has been shown to increase bone mass, decrease bone pain, improve mobility, and reduce the incidence of fractures. Sclerotic metaphyseal lines parallel to the growth plate are seen on long bone radiographs following cyclical intravenous therapy. These areas create stress risers within the bone that may act as foci for subsequent fractures as exemplified in this clinical case.

Methods: An 8-year-old girl with OI sustained a distal radial fracture following 3 years of treatment with 6-monthly intravenous zoledronate. Her diagnosis, response to treatment, and subsequent fracture at a sclerotic metaphyseal line is described.

Results: Peripheral quantitative computer tomography was used to characterise the presence of multiple stress risers at the distal forearm. Trabecular bone mineral density fluctuated from 34 to 126% compared to neighbouring 2-mm regions.

Conclusion: There remain many unanswered questions about optimal bisphosphonate treatment regimens in children with OI. The formation of stress risers following intravenous bisphosphonate treatment raises the hypothesis that a more frequent and low-dose bisphosphonate regimen would provide more uniform dosing of bone in the growing child and reduce the likelihood of fractures compared to current treatment practices.
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http://dx.doi.org/10.1159/000355111DOI Listing
December 2014

Intravenous zoledronic Acid given every 6 months in childhood osteoporosis.

Horm Res Paediatr 2013 18;80(3):179-84. Epub 2013 Sep 18.

Institute of Endocrinology and Diabetes, The Children's Hospital at Westmead, Sydney, N.S.W., Australia.

Aim: To evaluate the safety and efficacy of 12 months of zoledronic acid (ZA) administered every 6 months to children with osteoporosis.

Methods: Retrospective cohort study of 27 patients (16 male, 11 female) treated with ZA (0.05 mg/kg/dose) every 6 months for 1 year. 20 were immobile, 4 steroid-induced osteoporosis, 2 idiopathic osteoporosis and 1 neurofibromatosis type 1. 16 had long bone fractures and 12 had vertebral wedging at baseline. Mineral homeostasis, bone mineral density (BMD) and vertebral morphometry were evaluated at baseline and 12 months. Results were compared to published data on 3-monthly ZA treatment.

Results: Median age at ZA start was 10.5 years (range 6.2-13.3). Following the first infusion, 2 developed asymptomatic hypocalcemic, 14 developed temperature > 38°C, 13 aches/pain and 6 nausea. At 12 months, there was reduction in bone turnover and improvement in BMD and vertebral shape. No patient fractured after starting ZA. Growth was normal. Outcomes were similar to 3-monthly ZA.

Conclusion: ZA administered 6-monthly was associated with acute phase reaction to the first dose and improvement in BMD, reduction in bone turnover and improved vertebral shape at 12 months.
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http://dx.doi.org/10.1159/000354303DOI Listing
April 2014

Evaluation of bone mineral density and morphology using pQCT in children after spinal cord injury.

Dev Neurorehabil 2013 Dec 11;16(6):391-7. Epub 2013 Mar 11.

Institute of Endocrinology and Diabetes, The Sydney Children's Hospitals Network , Westmead, Sydney , Australia.

Objective: To evaluate the effects of spinal cord injury (SCI) on bone density and morphology in children using peripheral quantitative computer tomography (pQCT).

Design: Retrospective cohort study of 19 paediatric patients with SCI (9 paraplegics and 10 tetraplegics).

Results: There was significant reduction in tibial metaphysial volumetric bone mineral density (vBMD), diaphysial cortical cross-sectional area (CSA), cortical thickness and polar strength-strain index. There was a significant loss of calf muscle CSA. Those who were able to stand had greater trabecular vBMD, tibial cortical thickness and tibial muscle CSA Z-scores. Lower limb fractures did not occur if tibial trabecular vBMD was greater than 100 mg/cm³. Tibial geometry following SCI was more circular compared to controls.

Conclusions: pQCT provides a valuable insight into the regional changes in bone and muscle development in children following SCI. Residual muscle function with the ability to weight bear provides a significant benefit to bone development.
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http://dx.doi.org/10.3109/17518423.2012.762590DOI Listing
December 2013

Scientific bodies must take own action on emissions.

Authors:
Andrew Biggin

Nature 2007 Aug;448(7155):749

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http://dx.doi.org/10.1038/448749aDOI Listing
August 2007

Mutation screening of the mitochondrial genome using denaturing high-performance liquid chromatography.

Mol Genet Metab 2005 Jan 11;84(1):61-74. Epub 2004 Nov 11.

Western Sydney Genetics Program, Children's Hospital at Westmead, Sydney, NSW, Australia.

Over 170 known mutations of the mitochondrial genome are responsible for disease. Due to the unique features of mitochondrial genetics, such patients are clinically diverse and difficult to diagnose. As pathogenic mitochondrial DNA (mtDNA) mutations are mostly heteroplasmic, denaturing high-performance liquid chromatography (DHPLC) could be used to detect these heteroplasmic species and therefore act as a rapid screening test for mtDNA mutations. The entire mitochondrial genome was amplified by PCR in 40 overlapping regions. In addition, known mtDNA mutants were constructed for each of these regions using a PCR-based site-directed mutagenesis approach. These mutants were used as positive controls and showed a detection limit of 3-10% heteroplasmy by DHPLC (depending on the specific mutation) compared to 40% for conventional sequencing. To further validate the screening test, mtDNA from 17 patients with seven different pathogenic mutations was used to compare mutation detection by DHPLC and conventional sequencing. DHPLC had a sensitivity of 88% compared to 82% for sequencing. This increased to 100% sensitivity for DHPLC when excluding the m.8993T>G mutation. DHPLC analysis is therefore a sensitive, rapid and cost-effective method to screen for mutations in the mitochondrial genome. The role of pyrosequencing in the quantitation of mutant load for known mtDNA mutations was highlighted using the m.3243A>G mutation as an illustrative example. Pyrosequencing analysis was able to discriminate samples containing as little as 5% heteroplasmy and proved to be an accurate and reproducible method for estimation of mutant load.
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http://dx.doi.org/10.1016/j.ymgme.2004.09.011DOI Listing
January 2005

Detection of thirty novel FBN1 mutations in patients with Marfan syndrome or a related fibrillinopathy.

Hum Mutat 2004 Jan;23(1):99

Marfan Research Group, The Children's Hospital at Westmead, NSW, Australia.

Marfan syndrome (MFS) is a disorder of the extracellular matrix caused by mutations in the gene encoding fibrillin-1 (FBN1). Recent studies have illustrated the variability in disease severity and clinical manifestations of MFS. Useful genotype-phenotype correlations have been slow to emerge. We screened 57 unrelated patients with MFS or a Marfan-like phenotype using a combination of SSCP and/or DHPLC. We detected 49 different FBN1 mutations, 30 (62%) of which were novel. The mutations comprised 38 substitutions (78%), 10 deletions (20%), and one duplication (2%). There were 28 missense (57%), nine frameshift (18%), eight splice site (16%), and four nonsense mutations (8 %). Genotype-phenotype analysis revealed that patients with an identified FBN1 mutation were more likely to have ectopia lentis and cardiovascular complications compared to those without an identifiable mutation (relative risks of 4.6 and 1.9, respectively). Ectopia lentis was also found to be more prevalent in patients whose mutations involved a cysteine substitution (relative risk 1.6) and less prevalent in those with premature termination mutations (relative risk 0.4). In our hands, we achieved 93% mutation detection for DHPLC analysis of patients who fulfilled the Ghent criteria. Further analysis of detailed clinical information and mutation data may help to anticipate the clinical consequences of specific FBN1 mutations.
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http://dx.doi.org/10.1002/humu.9207DOI Listing
January 2004
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