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Herrou J, Picaud AS, Lassalle L, Pacot L, Chaussain C, Merzoug V, Hervé A, Gadion M, Rothenbuhler A, Kamenický P, Roux C, Linglart A, Duplan MB, Briot K. Prevalence of Enthesopathies in Adults With X-linked Hypophosphatemia: Analysis of Risk Factors. J Clin Endocrinol Metab 2022; 107:e224-e235. [PMID: 34406383 DOI: 10.1210/clinem/dgab580] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/10/2021] [Indexed: 11/19/2022]
Abstract
CONTEXT Enthesopathies are the determinant of a poor quality of life in adults with X-linked hypophosphatemia (XLH). OBJECTIVE To describe the prevalence of patients with enthesopathies and to identify the risk factors of having enthesopathies. METHODS Retrospective study in the French Reference Center for Rare Diseases of the Calcium and Phosphate Metabolism between June 2011 and December 2020. Adult XLH patients with full body X-rays performed using the EOS® low-dose radiation system and clinical data collected from medical records. The main outcome measures were demographics, PHEX mutation, conventional treatment, and dental disease with the presence of enthesopathies. RESULTS Of the 114 patients included (68% women, mean age 42.2 ± 14.3 years), PHEX mutation was found in 105 patients (94.6%), 86 (77.5%) had been treated during childhood. Enthesopathies (spine and/or pelvis) were present in 67% of the patients (n = 76). Patients with enthesopathies were significantly older (P = .001) and more frequently reported dental disease collected from medical records (P = .03). There was no correlation between the PHEX mutations and the presence of enthesopathies. Sixty-two patients had a radiographic dental examination in a reference center. Severe dental disease (number of missing teeth, number of teeth endodontically treated, alveolar bone loss, and proportion of patients with 5 abscesses or more) was significantly higher in patients with enthesopathies. CONCLUSION Adult XLH patients have a high prevalence of enthesopathies in symptomatic adults patients with XLH seen in a reference center. Age and severe dental disease were significantly associated with the presence of enthesopathies.
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Affiliation(s)
- Julia Herrou
- INSERM UMR 1153, Université de Paris, APHP Centre, Paris, France
- APHP Centre, Department of Rheumatology, Cochin Hospital, Paris, France
| | - Axelle Salcion Picaud
- APHP Centre, Department of Rheumatology, Cochin Hospital, Paris, France
- Reference Center for Rare Diseases of the Calcium and Phosphate Metabolism, OSCAR Network for Rare Bone and Calcium Phosphate Disorders, Paris, France
| | - Louis Lassalle
- APHP, Department of Radiology, Cochin Hospital, Paris, France
| | - Laurence Pacot
- APHP, Department of Genetics, Cochin Hospital, Paris, France
| | - Catherine Chaussain
- Reference Center for Rare Diseases of the Calcium and Phosphate Metabolism, OSCAR Network for Rare Bone and Calcium Phosphate Disorders, Paris, France
- Université de Paris, Medical and Dental Schools, Paris, France
- APHP, Department of Odontology, Bretonneau Hospital, HUPNVS, Paris, France
| | - Valérie Merzoug
- APHP, Department of Pediatric Radiology, Bicêtre Paris Saclay Hospital, Le Kremlin Bicêtre, France
| | - Agathe Hervé
- APHP, Department of Odontology, Bretonneau Hospital, HUPNVS, Paris, France
| | - Margaux Gadion
- APHP, Department of Odontology, Bretonneau Hospital, HUPNVS, Paris, France
| | - Anya Rothenbuhler
- Reference Center for Rare Diseases of the Calcium and Phosphate Metabolism, OSCAR Network for Rare Bone and Calcium Phosphate Disorders, Paris, France
- APHP, Department of Endocrinology and Diabetes for Children, Bicêtre Paris Saclay Hospital, Le Kremlin Bicêtre, France
- APHP, Plateforme d'expertise Paris Saclay maladies rares, Bicêtre Paris Saclay Hospital, Le Kremlin Bicêtre, France
| | - Peter Kamenický
- Reference Center for Rare Diseases of the Calcium and Phosphate Metabolism, OSCAR Network for Rare Bone and Calcium Phosphate Disorders, Paris, France
- Université Paris-Saclay, Inserm, Physiologie et Physiopathologie Endocriniennes, Le Kremlin-Bicêtre,France
| | - Christian Roux
- INSERM UMR 1153, Université de Paris, APHP Centre, Paris, France
- APHP Centre, Department of Rheumatology, Cochin Hospital, Paris, France
- Reference Center for Rare Diseases of the Calcium and Phosphate Metabolism, OSCAR Network for Rare Bone and Calcium Phosphate Disorders, Paris, France
| | - Agnès Linglart
- Reference Center for Rare Diseases of the Calcium and Phosphate Metabolism, OSCAR Network for Rare Bone and Calcium Phosphate Disorders, Paris, France
- APHP, Department of Endocrinology and Diabetes for Children, Bicêtre Paris Saclay Hospital, Le Kremlin Bicêtre, France
- APHP, Plateforme d'expertise Paris Saclay maladies rares, Bicêtre Paris Saclay Hospital, Le Kremlin Bicêtre, France
| | - Martin Biosse Duplan
- Reference Center for Rare Diseases of the Calcium and Phosphate Metabolism, OSCAR Network for Rare Bone and Calcium Phosphate Disorders, Paris, France
- Université de Paris, Medical and Dental Schools, Paris, France
- APHP, Department of Odontology, Bretonneau Hospital, HUPNVS, Paris, France
| | - Karine Briot
- INSERM UMR 1153, Université de Paris, APHP Centre, Paris, France
- APHP Centre, Department of Rheumatology, Cochin Hospital, Paris, France
- Reference Center for Rare Diseases of the Calcium and Phosphate Metabolism, OSCAR Network for Rare Bone and Calcium Phosphate Disorders, Paris, France
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Mindler GT, Kranzl A, Stauffer A, Kocijan R, Ganger R, Radler C, Haeusler G, Raimann A. Lower Limb Deformity and Gait Deviations Among Adolescents and Adults With X-Linked Hypophosphatemia. Front Endocrinol (Lausanne) 2021; 12:754084. [PMID: 34646241 PMCID: PMC8503556 DOI: 10.3389/fendo.2021.754084] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/05/2021] [Accepted: 08/31/2021] [Indexed: 11/13/2022] Open
Abstract
BACKGROUND X-linked hypophosphatemia (XLH) is a rare genetic disorder characterized by lower limb deformity, gait and joint problems, and pain. Hence, quality of life is substantially impaired. This study aimed to assess lower limb deformity, specific radiographic changes, and gait deviations among adolescents and adults with XLH. DESIGN Data on laboratory examination and gait analysis results were analyzed retrospectively. Deformities, osteoarthritis, pseudofractures, and enthesopathies on lower limb radiographs were investigated. Gait analysis findings were compared between the XLH group and the control group comprising healthy adults. PATIENTS AND CONTROLS Radiographic outcomes were assessed retrospectively in 43 patients with XLH (28 female, 15 male). Gait analysis data was available in 29 patients with confirmed XLH and compared to a healthy reference cohort (n=76). RESULTS Patients with XLH had a lower gait quality compared to healthy controls (Gait deviation index GDI 65.9% +/- 16.2). About 48.3% of the study population presented with a greater lateral trunk lean, commonly referred to as waddling gait. A higher BMI and mechanical axis deviation of the lower limbs were associated with lower gait scores and greater lateral trunk lean. Patients with radiologic signs of enthesopathies had a lower GDI. CONCLUSIONS This study showed for the first time that lower limb deformity, BMI, and typical features of XLH such as enthesopathies negatively affected gait quality among adolescents and adults with XLH.
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Affiliation(s)
- Gabriel T. Mindler
- Department of Pediatric Orthopaedics, Orthopaedic Hospital Speising, Vienna, Austria
- Vienna Bone and Growth Center, Vienna, Austria
| | - Andreas Kranzl
- Vienna Bone and Growth Center, Vienna, Austria
- Laboratory for Gait and Movement Analysis, Orthopaedic Hospital Speising, Vienna, Austria
| | - Alexandra Stauffer
- Department of Pediatric Orthopaedics, Orthopaedic Hospital Speising, Vienna, Austria
- Vienna Bone and Growth Center, Vienna, Austria
| | - Roland Kocijan
- Vienna Bone and Growth Center, Vienna, Austria
- Ludwig Boltzmann Institute of Osteology at Hanusch Hospital of OEGK and AUVA Trauma Center Meidling, 1st Medical Department, Hanusch Hospital, Vienna, Austria
- Medical Faculty of Bone Diseases, Sigmund Freud University, Vienna, Austria
| | - Rudolf Ganger
- Department of Pediatric Orthopaedics, Orthopaedic Hospital Speising, Vienna, Austria
- Vienna Bone and Growth Center, Vienna, Austria
| | - Christof Radler
- Department of Pediatric Orthopaedics, Orthopaedic Hospital Speising, Vienna, Austria
- Vienna Bone and Growth Center, Vienna, Austria
| | - Gabriele Haeusler
- Vienna Bone and Growth Center, Vienna, Austria
- Department of Pediatrics and Adolescent Medicine, Division of Pediatric Pulmonology, Allergology and Endocrinology, Medical University of Vienna, Vienna, Austria
| | - Adalbert Raimann
- Vienna Bone and Growth Center, Vienna, Austria
- Department of Pediatrics and Adolescent Medicine, Division of Pediatric Pulmonology, Allergology and Endocrinology, Medical University of Vienna, Vienna, Austria
- *Correspondence: Adalbert Raimann,
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Mao M, Carpenter TO, Whyte MP, Skrinar A, Chen CY, San Martin J, Rogol AD. Growth Curves for Children with X-linked Hypophosphatemia. J Clin Endocrinol Metab 2020; 105:dgaa495. [PMID: 32721016 PMCID: PMC7448934 DOI: 10.1210/clinem/dgaa495] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/13/2020] [Accepted: 07/24/2020] [Indexed: 11/27/2022]
Abstract
CONTEXT We characterized linear growth in infants and children with X-linked hypophosphatemia (XLH). OBJECTIVE Provide linear growth curves for children with XLH from birth to early adolescence. DESIGN Data from 4 prior studies of XLH were pooled to construct growth curves. UX023-CL002 was an observational, retrospective chart review. Pretreatment data were collected from 3 interventional trials: two phase 2 trials (UX023-CL201, UX023-CL205) and a phase 3 trial (UX023-CL301). SETTING Medical centers with expertise in treating XLH. PATIENTS Children with XLH, 1-14 years of age. INTERVENTION None. MAIN OUTCOME MEASURE Height-for-age linear growth curves, including values for the 5th, 10th, 25th, 50th, 75th, 90th, and 95th percentiles for children with XLH compared to population norms. RESULTS A total of 228 patients (132 girls, 96 boys) with 2381 height measurements were included. Nearly all subjects (> 99%) reported prior management with supplementation therapy. Compared to the Center for Disease Control and Prevention growth curves, boys at age 3 months, 6 months, 9 months, 1 year, and 2 years had median height percentiles of 46%, 37%, 26%, 18%, and 5%, respectively; for girls the median height percentiles were 52%, 37%, 25%, 18%, and 7%, respectively. Annual growth in children with XLH fell below that of healthy children near 1 year of age and progressively declined during early childhood, with all median height percentiles < 8% between 2 and 12 years old. CONCLUSION Children with XLH show decreased height gain by 1 year of age and remain below population norms thereafter. These data will help evaluate therapeutic interventions on linear growth for pediatric XLH.
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Affiliation(s)
- Meng Mao
- UBiometrics, Ultragenyx Pharmaceutical Inc., Novato, California
| | - Thomas O Carpenter
- Department of Pediatrics, Department of Orthopaedics and Rehabilitation, Yale University School of Medicine, New Haven, Connecticut
| | - Michael P Whyte
- Division of Bone and Mineral Diseases, Department of Internal Medicine, Washington University School of Medicine, St. Louis, Missouri
- Center for Metabolic Bone Disease and Molecular Research, Shriners Hospitals for Children - St Louis, St Louis, Missouri
| | - Alison Skrinar
- Clinical Outcomes, Research and Evaluation, Ultragenyx Pharmaceutical Inc., Novato, California
| | - Chao-Yin Chen
- UBiometrics, Ultragenyx Pharmaceutical Inc., Novato, California
| | - Javier San Martin
- Clinical Development, Ultragenyx Pharmaceutical Inc., Novato, California
| | - Alan D Rogol
- Pediatrics, University of Virginia School of Medicine, Charlottesville, Virginia
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Abstract
PURPOSE OF REVIEW This review summarizes current understanding of generalized arterial calcification of infancy (GACI), emphasizing pathophysiology, clinical presentation, and approaches and controversies in management. RECENT FINDINGS Identification of causative ENPP1 mutations revealed that GACI arises from deficiencies in inorganic pyrophosphate (leading to calcifications) and adenosine monophosphate (leading to intimal proliferation). Identification of genotypic and phenotypic overlap with pseudoxanthoma elasticum and autosomal recessive hypophosphatemic rickets further advanced understanding of GACI as a complex, multisystemic disease. Clinical data is limited to small, retrospective samples; it is therefore unknown whether commonly used medications, such as bisphosphonates and hypophosphatemia treatment, are therapeutic or potentially harmful. ENPP1-Fc replacement represents a promising approach warranting further study. Knowledge gaps in natural history place clinicians at high risk of assigning causality to interventions that are correlated with changes in clinical status. There is thus a critical need for improved natural history studies to develop and test targeted therapies.
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Affiliation(s)
- Alison M Boyce
- Skeletal Diseases and Mineral Homeostasis Section, National Institute of Dental and Craniofacial Research, National Institutes of Health, 30 Convent Drive Room 218 MSC 4320, Bethesda, MD, 20892, USA.
| | - Rachel I Gafni
- Skeletal Diseases and Mineral Homeostasis Section, National Institute of Dental and Craniofacial Research, National Institutes of Health, 30 Convent Drive Room 218 MSC 4320, Bethesda, MD, 20892, USA
| | - Carlos R Ferreira
- Medical Genomics and Metabolic Genetics Branch, National Human Genome Research Institute, National Institutes of Health, Bethesda, MD, USA
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Abstract
X-linked hypophosphataemia (XLH) is the most prevalent form of hereditary rickets characterized by an alteration of phosphate metabolism which frequently leads to the appearance of fractures, bone deformities and growth delay. Although the mechanism of growth impairment in patients with XLH still needs to be clarified, it is known that this alteration is not due to genetic or endocrine factors. A potential explanation for the impairment of growth in this disease is the alteration of the growth plate, a structure responsible for longitudinal growth of bones. Some of the findings in the growth plate of patients with XLH include atypical organization of chondrocytes due to low rates of proliferation and apoptosis and disturbance of chondrocyte hypertrophy, overactivation of the mitogen-activated protein kinase (MAPK) signalling pathway and upregulation of phosphorylated extracellular signal-regulated kinase (pERK). Conventional treatment of XLH (consisting of oral phosphate supplements and active vitamin D analogues) is often insufficient for the longitudinal growth of bone, but other strategies based on recombinant growth hormone or therapies targeting fibroblast growth factor 23 (FGF23) or its receptor, such as burosumab, have shown promising results. This article briefly describes the relationship between XLH and growth retardation, and how to address this alteration in patients with XLH.
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Affiliation(s)
- Fernando Santos Rodríguez
- Unidad de Nefrología Pediátrica, Hospital Universitario Central de Asturias, Universidad de Oviedo, Oviedo, Spain.
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Raimann A, Mehany SN, Feil P, Weber M, Pietschmann P, Boni-Mikats A, Klepochova R, Krššák M, Häusler G, Schneider J, Patsch JM, Raum K. Decreased Compressional Sound Velocity Is an Indicator for Compromised Bone Stiffness in X-Linked Hypophosphatemic Rickets (XLH). Front Endocrinol (Lausanne) 2020; 11:355. [PMID: 32582030 PMCID: PMC7296046 DOI: 10.3389/fendo.2020.00355] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/01/2020] [Accepted: 05/06/2020] [Indexed: 12/02/2022] Open
Abstract
Objectives: To assess the diagnostic potential of bidirectional axial transmission (BDAT) ultrasound, and high-resolution peripheral quantitative computed tomography (HR-pQCT) in X-linked hypophosphatemia (XLH, OMIM #307800), a rare genetic disorder of phosphate metabolism caused by mutations in the PHEX gene. Methods: BDAT bone ultrasound was performed at the non-dominant distal radius (33% relative to distal head) and the central left tibia (50%) in eight XLH patients aged between 4.2 and 20.8 years and compared to twenty-nine healthy controls aged between 5.8 and 22.4 years. In eighteen controls, only radius measurements were performed. Four patients and four controls opted to participate in HR-pQCT scanning of the ultradistal radius and tibia. Results: Bone ultrasound was feasible in patients and controls as young as 4 years of age. The velocity of the first arriving signal (νFAS) in BDAT ultrasound was significantly lower in XLH patients compared to healthy controls: In the radius, mean νFAS of XLH patients and controls was 3599 ± 106 and 3866 ± 142 m/s, respectively (-6.9%; p < 0.001). In the tibia, it was 3578 ± 129 and 3762 ± 124 m/s, respectively (-4.9%; p = 0.006). HR-pQCT showed a higher trabecular thickness in the tibia of XLH patients (+16.7%; p = 0.021). Conclusions: Quantitative bone ultrasound revealed significant differences in cortical bone quality of young XLH patients as compared to controls. Regular monitoring of XLH patients by a radiation-free technology such as BDAT might provide valuable information on bone quality and contribute to the optimization of treatment. Further studies are needed to establish this affordable and time efficient method in the XLH patients.
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Affiliation(s)
- Adalbert Raimann
- Division of Pediatric Pulmonology, Allergology and Endocrinology, Department of Pediatrics and Adolescent Medicine, Comprehensive Center for Pediatrics, Medical University of Vienna, Vienna, Austria
| | - Sarah N. Mehany
- Division of General and Pediatric Radiology, Department of Biomedical Imaging and Image-guided Therapy, Medical University of Vienna, Vienna, Austria
| | - Patricia Feil
- Division of Pediatric Surgery, Department of Surgery, Medical University of Vienna, Vienna, Austria
| | - Michael Weber
- Division of General and Pediatric Radiology, Department of Biomedical Imaging and Image-guided Therapy, Medical University of Vienna, Vienna, Austria
| | - Peter Pietschmann
- Department of Pathophysiology and Allergy Research, Medical University of Vienna, Vienna, Austria
| | - Andrea Boni-Mikats
- Division of General and Pediatric Radiology, Department of Biomedical Imaging and Image-guided Therapy, Medical University of Vienna, Vienna, Austria
| | - Radka Klepochova
- Department of Biomedical Imaging and Image-guided Therapy, The High Field MR Centre, Vienna, Austria
| | - Martin Krššák
- Department of Biomedical Imaging and Image-guided Therapy, The High Field MR Centre, Vienna, Austria
- Division of Endocrinology and Metabolism, Department of Medicine III, Medical University of Vienna, Vienna, Austria
- Christian Doppler Laboratory for Clinical Molecular MR Imaging—MOLIMA, Vienna, Austria
| | - Gabriele Häusler
- Division of Pediatric Pulmonology, Allergology and Endocrinology, Department of Pediatrics and Adolescent Medicine, Comprehensive Center for Pediatrics, Medical University of Vienna, Vienna, Austria
| | - Johannes Schneider
- Charité—Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, BCRT - Berlin Institute of Health Center for Regenerative Therapies, Berlin, Germany
| | - Janina M. Patsch
- Division of Pediatric Pulmonology, Allergology and Endocrinology, Department of Pediatrics and Adolescent Medicine, Comprehensive Center for Pediatrics, Medical University of Vienna, Vienna, Austria
- Division of General and Pediatric Radiology, Department of Biomedical Imaging and Image-guided Therapy, Medical University of Vienna, Vienna, Austria
- *Correspondence: Janina M. Patsch
| | - Kay Raum
- Charité—Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, BCRT - Berlin Institute of Health Center for Regenerative Therapies, Berlin, Germany
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Abstract
Fibroblast growth factor 23 (FGF23), one of the endocrine fibroblast growth factors, is a principal regulator in the maintenance of serum phosphorus concentration. Binding to its cofactor αKlotho and a fibroblast growth factor receptor is essential for its activity. Its regulation and interaction with other factors in the bone-parathyroid-kidney axis is complex. FGF23 reduces serum phosphorus concentration through decreased reabsorption of phosphorus in the kidney and by decreasing 1,25 dihydroxyvitamin D (1,25(OH)2D) concentrations. Various FGF23-mediated disorders of renal phosphate wasting share similar clinical and biochemical features. The most common of these is X-linked hypophosphatemia (XLH). Additional disorders of FGF23 excess include autosomal dominant hypophosphatemic rickets, autosomal recessive hypophosphatemic rickets, fibrous dysplasia, and tumor-induced osteomalacia. Treatment is challenging, requiring careful monitoring and titration of dosages to optimize effectiveness and to balance side effects. Conventional therapy for XLH and other disorders of FGF23-mediated hypophosphatemia involves multiple daily doses of oral phosphate salts and active vitamin D analogs, such as calcitriol or alfacalcidol. Additional treatments may be used to help address side effects of conventional therapy such as thiazides to address hypercalciuria or nephrocalcinosis, and calcimimetics to manage hyperparathyroidism. The recent development and approval of an anti-FGF23 antibody, burosumab, for use in XLH provides a novel treatment option.
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Affiliation(s)
- Anisha Gohil
- Indiana University School of Medicine, Riley Hospital for Children, Fellow, Endocrinology and Diabetes, 705 Riley Hospital Drive, Room 5960, Indianapolis, IN 46202, USA, E-mail:
| | - Erik A Imel
- Indiana University School of Medicine, Riley Hospital for Children, Associate Professor of Medicine and Pediatrics, 1120 West Michigan Street, CL 459, Indianapolis, IN 46202, USA
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Hansen S, Shanbhogue VV, Jørgensen NR, Beck-Nielsen SS. Elevated Bone Remodeling Markers of CTX and P1NP in Addition to Sclerostin in Patients with X-linked Hypophosphatemia: A Cross-Sectional Controlled Study. Calcif Tissue Int 2019; 104:591-598. [PMID: 30710161 DOI: 10.1007/s00223-019-00526-z] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/28/2018] [Accepted: 01/16/2019] [Indexed: 02/06/2023]
Abstract
Aspects of bone remodeling have only been scarcely studied in X-linked hypophosphatemia (XLH). In this cross-sectional controlled study, we assessed biochemical indices of bone remodeling and sclerostin in 27 adult patients (median age 47 [range 24-79] years, 19 women, 8 men) with XLH matched with 81 healthy control subjects (1:3) with respect to age-, sex-, and menopausal status. Markers of bone resorption (carboxyterminal cross-linked telopeptide of type 1 collagen, CTX) and formation (N-terminal propeptide of type 1 procollagen, P1NP) were higher in XLH patients compared to controls (median [IQR] 810 [500-1340] vs 485 [265-715] ng/l and 90 [57-136] vs 49 [39-65] ug/l, respectively, both p < 0.001) as well as sclerostin (0.81 [0.60-1.18] vs 0.54 [0.45-0.69] ng/ml, p < 0.001). Similar differences were found when comparing currently treated (with phosphate and alfacalcidol) (n = 11) and untreated (n = 16) XLH patients with their respective controls. We found no significant associations with treatment status and indices of bone remodeling or sclerostin although sclerostin tended to be increased in untreated versus treated (p = 0.06). In contrast to previous histomorphometric studies suggesting a low remodeling activity in XLH, these biochemical indices suggest high osteoblast and osteoclast activity. Further studies are needed to ascertain if the higher sclerostin level in XLH is related to osteocyte dysfunction or represents a secondary phenomenon.
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Affiliation(s)
- Stinus Hansen
- Department of Endocrinology, Hospital South West Jutland, Esbjerg, Denmark.
| | | | - Niklas Rye Jørgensen
- Department of Clinical Biochemistry, Rigshospitalet, Glostrup, Denmark
- OPEN, Odense Patient Data Explorative Network, Odense University Hospital/Institute of Clinical Research, University of Southern Denmark, Odense, Denmark
| | - Signe Sparre Beck-Nielsen
- Department of Pediatrics, Kolding Hospital at Lillebaelt Hospital, Kolding, Denmark
- Department of Regional Health Research, University of Southern Denmark, Odense, Denmark
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Chesher D, Oddy M, Darbar U, Sayal P, Casey A, Ryan A, Sechi A, Simister C, Waters A, Wedatilake Y, Lachmann RH, Murphy E. Outcome of adult patients with X-linked hypophosphatemia caused by PHEX gene mutations. J Inherit Metab Dis 2018; 41:865-876. [PMID: 29460029 PMCID: PMC6133187 DOI: 10.1007/s10545-018-0147-6] [Citation(s) in RCA: 82] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/01/2017] [Revised: 01/07/2018] [Accepted: 01/24/2018] [Indexed: 01/09/2023]
Abstract
X-linked hypophosphatemia (XLH) is the most common monogenic disorder causing hypophosphatemia. This case-note review documents the clinical features and the complications of treatment in 59 adults (19 male, 40 female) with XLH. XLH is associated with a large number of private mutations; 37 different mutations in the PHEX gene were identified in this cohort, 14 of which have not been previously reported. Orthopaedic involvement requiring surgical intervention (osteotomy) was frequent. Joint replacement and decompressive laminectomy were observed in those older than 40 years. Dental disease (63%), nephrocalcinosis (42%), and hearing impairment (14%) were also common. The rarity of the disease and the large number of variants make it difficult to discern specific genotype-phenotype relationships. A new treatment, an anti-FGF23 antibody, that may affect the natural history of the disease is currently being investigated in clinical trials.
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Affiliation(s)
- Douglas Chesher
- Charles Dent Metabolic Unit, National Hospital for Neurology and Neurosurgery, Queen Square, London, WC1N 3BG, UK
- New South Wales Health Pathology, Royal North Shore Hospital, St Leonards, NSW, Australia
| | - Michael Oddy
- Department of Trauma and Orthopaedics, University College London Hospitals NHS Foundation Trust, London, UK
| | - Ulpee Darbar
- Department of Periodontology, Eastman Dental Hospital, London, UK
| | - Parag Sayal
- Department of Neurosurgery, National Hospital for Neurology and Neurosurgery, Queen Square, London, UK
| | - Adrian Casey
- Department of Neurosurgery, National Hospital for Neurology and Neurosurgery, Queen Square, London, UK
| | - Aidan Ryan
- Charles Dent Metabolic Unit, National Hospital for Neurology and Neurosurgery, Queen Square, London, WC1N 3BG, UK
- Chemical Pathology and Metabolic Medicine, University Hospital Southampton NHS Foundation Trust, Southampton, UK
| | - Annalisa Sechi
- Charles Dent Metabolic Unit, National Hospital for Neurology and Neurosurgery, Queen Square, London, WC1N 3BG, UK
- Centre for Rare Disease, Academic Hospital of Udine, Udine, Italy
| | - Charlotte Simister
- Charles Dent Metabolic Unit, National Hospital for Neurology and Neurosurgery, Queen Square, London, WC1N 3BG, UK
| | - Aoife Waters
- Institute of Child Health, Great Ormond Street Hospital for Children NHS Foundation Trust, London, UK
| | - Yehani Wedatilake
- Charles Dent Metabolic Unit, National Hospital for Neurology and Neurosurgery, Queen Square, London, WC1N 3BG, UK
- Imperial College London NHS Foundation Trust, London, UK
| | - Robin H Lachmann
- Charles Dent Metabolic Unit, National Hospital for Neurology and Neurosurgery, Queen Square, London, WC1N 3BG, UK
| | - Elaine Murphy
- Charles Dent Metabolic Unit, National Hospital for Neurology and Neurosurgery, Queen Square, London, WC1N 3BG, UK.
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10
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Carpenter TO, Whyte MP, Imel EA, Boot AM, Högler W, Linglart A, Padidela R, Van't Hoff W, Mao M, Chen CY, Skrinar A, Kakkis E, San Martin J, Portale AA. Burosumab Therapy in Children with X-Linked Hypophosphatemia. N Engl J Med 2018; 378:1987-1998. [PMID: 29791829 DOI: 10.1056/nejmoa1714641] [Citation(s) in RCA: 265] [Impact Index Per Article: 44.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
BACKGROUND X-linked hypophosphatemia is characterized by increased secretion of fibroblast growth factor 23 (FGF-23), which leads to hypophosphatemia and consequently rickets, osteomalacia, and skeletal deformities. We investigated burosumab, a monoclonal antibody that targets FGF-23, in patients with X-linked hypophosphatemia. METHODS In an open-label, phase 2 trial, we randomly assigned 52 children with X-linked hypophosphatemia, in a 1:1 ratio, to receive subcutaneous burosumab either every 2 weeks or every 4 weeks; the dose was adjusted to achieve a serum phosphorus level at the low end of the normal range. The primary end point was the change from baseline to weeks 40 and 64 in the Thacher rickets severity total score (ranging from 0 to 10, with higher scores indicating greater disease severity). In addition, the Radiographic Global Impression of Change was used to evaluate rachitic changes from baseline to week 40 and to week 64. Additional end points were changes in pharmacodynamic markers, linear growth, physical ability, and patient-reported outcomes and the incidence of adverse events. RESULTS The mean Thacher rickets severity total score decreased from 1.9 at baseline to 0.8 at week 40 with every-2-week dosing and from 1.7 at baseline to 1.1 at week 40 with every-4-week dosing (P<0.001 for both comparisons); these improvements persisted at week 64. The mean serum phosphorus level increased after the first dose in both groups, and more than half the patients in both groups had levels within the normal range (3.2 to 6.1 mg per deciliter [1.0 to 2.0 mmol per liter]) by week 6. Stable serum phosphorus levels were maintained through week 64 with every-2-week dosing. Renal tubular phosphate reabsorption increased from baseline in both groups, with an overall mean increase of 0.98 mg per deciliter (0.32 mmol per liter). The mean dose of burosumab at week 40 was 0.98 mg per kilogram of body weight with every-2-week dosing and 1.50 mg per kilogram with every-4-week dosing. Across both groups, the mean serum alkaline phosphatase level decreased from 459 U per liter at baseline to 369 U per liter at week 64. The mean standing-height z score increased in both groups, with greater improvement seen at all time points with every-2-week dosing (an increase from baseline of 0.19 at week 64) than with every-4-week dosing (an increase from baseline of 0.12 at week 64). Physical ability improved and pain decreased. Nearly all the adverse events were mild or moderate in severity. CONCLUSIONS In children with X-linked hypophosphatemia, treatment with burosumab improved renal tubular phosphate reabsorption, serum phosphorus levels, linear growth, and physical function and reduced pain and the severity of rickets. (Funded by Ultragenyx Pharmaceutical and Kyowa Hakko Kirin; ClinicalTrials.gov number, NCT02163577 ; EudraCT number, 2014-000406-35 ).
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Affiliation(s)
- Thomas O Carpenter
- From Yale University School of Medicine, New Haven, CT (T.O.C.); Shriners Hospital for Children and Division of Bone and Mineral Diseases, Department of Internal Medicine, Washington University School of Medicine, St. Louis (M.P.W.); Indiana University School of Medicine, Indianapolis (E.A.I.); University of Groningen, Groningen, the Netherlands (A.M.B.); Birmingham Children's Hospital, Birmingham (W. Högler), Royal Manchester Children's Hospital, Manchester (R.P.), and Great Ormond Street Hospital, London (W. van't Hoff) - all in the United Kingdom; Assistance Publique-Hôpitaux de Paris Hôpital Bicêtre, Paris (A.L.); and Ultragenyx Pharmaceutical, Novato (M.M., C.-Y.C., A.S., E.K., J.S.M.), and University of California at San Francisco, San Francisco (A.A.P.) - both in California
| | - Michael P Whyte
- From Yale University School of Medicine, New Haven, CT (T.O.C.); Shriners Hospital for Children and Division of Bone and Mineral Diseases, Department of Internal Medicine, Washington University School of Medicine, St. Louis (M.P.W.); Indiana University School of Medicine, Indianapolis (E.A.I.); University of Groningen, Groningen, the Netherlands (A.M.B.); Birmingham Children's Hospital, Birmingham (W. Högler), Royal Manchester Children's Hospital, Manchester (R.P.), and Great Ormond Street Hospital, London (W. van't Hoff) - all in the United Kingdom; Assistance Publique-Hôpitaux de Paris Hôpital Bicêtre, Paris (A.L.); and Ultragenyx Pharmaceutical, Novato (M.M., C.-Y.C., A.S., E.K., J.S.M.), and University of California at San Francisco, San Francisco (A.A.P.) - both in California
| | - Erik A Imel
- From Yale University School of Medicine, New Haven, CT (T.O.C.); Shriners Hospital for Children and Division of Bone and Mineral Diseases, Department of Internal Medicine, Washington University School of Medicine, St. Louis (M.P.W.); Indiana University School of Medicine, Indianapolis (E.A.I.); University of Groningen, Groningen, the Netherlands (A.M.B.); Birmingham Children's Hospital, Birmingham (W. Högler), Royal Manchester Children's Hospital, Manchester (R.P.), and Great Ormond Street Hospital, London (W. van't Hoff) - all in the United Kingdom; Assistance Publique-Hôpitaux de Paris Hôpital Bicêtre, Paris (A.L.); and Ultragenyx Pharmaceutical, Novato (M.M., C.-Y.C., A.S., E.K., J.S.M.), and University of California at San Francisco, San Francisco (A.A.P.) - both in California
| | - Annemieke M Boot
- From Yale University School of Medicine, New Haven, CT (T.O.C.); Shriners Hospital for Children and Division of Bone and Mineral Diseases, Department of Internal Medicine, Washington University School of Medicine, St. Louis (M.P.W.); Indiana University School of Medicine, Indianapolis (E.A.I.); University of Groningen, Groningen, the Netherlands (A.M.B.); Birmingham Children's Hospital, Birmingham (W. Högler), Royal Manchester Children's Hospital, Manchester (R.P.), and Great Ormond Street Hospital, London (W. van't Hoff) - all in the United Kingdom; Assistance Publique-Hôpitaux de Paris Hôpital Bicêtre, Paris (A.L.); and Ultragenyx Pharmaceutical, Novato (M.M., C.-Y.C., A.S., E.K., J.S.M.), and University of California at San Francisco, San Francisco (A.A.P.) - both in California
| | - Wolfgang Högler
- From Yale University School of Medicine, New Haven, CT (T.O.C.); Shriners Hospital for Children and Division of Bone and Mineral Diseases, Department of Internal Medicine, Washington University School of Medicine, St. Louis (M.P.W.); Indiana University School of Medicine, Indianapolis (E.A.I.); University of Groningen, Groningen, the Netherlands (A.M.B.); Birmingham Children's Hospital, Birmingham (W. Högler), Royal Manchester Children's Hospital, Manchester (R.P.), and Great Ormond Street Hospital, London (W. van't Hoff) - all in the United Kingdom; Assistance Publique-Hôpitaux de Paris Hôpital Bicêtre, Paris (A.L.); and Ultragenyx Pharmaceutical, Novato (M.M., C.-Y.C., A.S., E.K., J.S.M.), and University of California at San Francisco, San Francisco (A.A.P.) - both in California
| | - Agnès Linglart
- From Yale University School of Medicine, New Haven, CT (T.O.C.); Shriners Hospital for Children and Division of Bone and Mineral Diseases, Department of Internal Medicine, Washington University School of Medicine, St. Louis (M.P.W.); Indiana University School of Medicine, Indianapolis (E.A.I.); University of Groningen, Groningen, the Netherlands (A.M.B.); Birmingham Children's Hospital, Birmingham (W. Högler), Royal Manchester Children's Hospital, Manchester (R.P.), and Great Ormond Street Hospital, London (W. van't Hoff) - all in the United Kingdom; Assistance Publique-Hôpitaux de Paris Hôpital Bicêtre, Paris (A.L.); and Ultragenyx Pharmaceutical, Novato (M.M., C.-Y.C., A.S., E.K., J.S.M.), and University of California at San Francisco, San Francisco (A.A.P.) - both in California
| | - Raja Padidela
- From Yale University School of Medicine, New Haven, CT (T.O.C.); Shriners Hospital for Children and Division of Bone and Mineral Diseases, Department of Internal Medicine, Washington University School of Medicine, St. Louis (M.P.W.); Indiana University School of Medicine, Indianapolis (E.A.I.); University of Groningen, Groningen, the Netherlands (A.M.B.); Birmingham Children's Hospital, Birmingham (W. Högler), Royal Manchester Children's Hospital, Manchester (R.P.), and Great Ormond Street Hospital, London (W. van't Hoff) - all in the United Kingdom; Assistance Publique-Hôpitaux de Paris Hôpital Bicêtre, Paris (A.L.); and Ultragenyx Pharmaceutical, Novato (M.M., C.-Y.C., A.S., E.K., J.S.M.), and University of California at San Francisco, San Francisco (A.A.P.) - both in California
| | - William Van't Hoff
- From Yale University School of Medicine, New Haven, CT (T.O.C.); Shriners Hospital for Children and Division of Bone and Mineral Diseases, Department of Internal Medicine, Washington University School of Medicine, St. Louis (M.P.W.); Indiana University School of Medicine, Indianapolis (E.A.I.); University of Groningen, Groningen, the Netherlands (A.M.B.); Birmingham Children's Hospital, Birmingham (W. Högler), Royal Manchester Children's Hospital, Manchester (R.P.), and Great Ormond Street Hospital, London (W. van't Hoff) - all in the United Kingdom; Assistance Publique-Hôpitaux de Paris Hôpital Bicêtre, Paris (A.L.); and Ultragenyx Pharmaceutical, Novato (M.M., C.-Y.C., A.S., E.K., J.S.M.), and University of California at San Francisco, San Francisco (A.A.P.) - both in California
| | - Meng Mao
- From Yale University School of Medicine, New Haven, CT (T.O.C.); Shriners Hospital for Children and Division of Bone and Mineral Diseases, Department of Internal Medicine, Washington University School of Medicine, St. Louis (M.P.W.); Indiana University School of Medicine, Indianapolis (E.A.I.); University of Groningen, Groningen, the Netherlands (A.M.B.); Birmingham Children's Hospital, Birmingham (W. Högler), Royal Manchester Children's Hospital, Manchester (R.P.), and Great Ormond Street Hospital, London (W. van't Hoff) - all in the United Kingdom; Assistance Publique-Hôpitaux de Paris Hôpital Bicêtre, Paris (A.L.); and Ultragenyx Pharmaceutical, Novato (M.M., C.-Y.C., A.S., E.K., J.S.M.), and University of California at San Francisco, San Francisco (A.A.P.) - both in California
| | - Chao-Yin Chen
- From Yale University School of Medicine, New Haven, CT (T.O.C.); Shriners Hospital for Children and Division of Bone and Mineral Diseases, Department of Internal Medicine, Washington University School of Medicine, St. Louis (M.P.W.); Indiana University School of Medicine, Indianapolis (E.A.I.); University of Groningen, Groningen, the Netherlands (A.M.B.); Birmingham Children's Hospital, Birmingham (W. Högler), Royal Manchester Children's Hospital, Manchester (R.P.), and Great Ormond Street Hospital, London (W. van't Hoff) - all in the United Kingdom; Assistance Publique-Hôpitaux de Paris Hôpital Bicêtre, Paris (A.L.); and Ultragenyx Pharmaceutical, Novato (M.M., C.-Y.C., A.S., E.K., J.S.M.), and University of California at San Francisco, San Francisco (A.A.P.) - both in California
| | - Alison Skrinar
- From Yale University School of Medicine, New Haven, CT (T.O.C.); Shriners Hospital for Children and Division of Bone and Mineral Diseases, Department of Internal Medicine, Washington University School of Medicine, St. Louis (M.P.W.); Indiana University School of Medicine, Indianapolis (E.A.I.); University of Groningen, Groningen, the Netherlands (A.M.B.); Birmingham Children's Hospital, Birmingham (W. Högler), Royal Manchester Children's Hospital, Manchester (R.P.), and Great Ormond Street Hospital, London (W. van't Hoff) - all in the United Kingdom; Assistance Publique-Hôpitaux de Paris Hôpital Bicêtre, Paris (A.L.); and Ultragenyx Pharmaceutical, Novato (M.M., C.-Y.C., A.S., E.K., J.S.M.), and University of California at San Francisco, San Francisco (A.A.P.) - both in California
| | - Emil Kakkis
- From Yale University School of Medicine, New Haven, CT (T.O.C.); Shriners Hospital for Children and Division of Bone and Mineral Diseases, Department of Internal Medicine, Washington University School of Medicine, St. Louis (M.P.W.); Indiana University School of Medicine, Indianapolis (E.A.I.); University of Groningen, Groningen, the Netherlands (A.M.B.); Birmingham Children's Hospital, Birmingham (W. Högler), Royal Manchester Children's Hospital, Manchester (R.P.), and Great Ormond Street Hospital, London (W. van't Hoff) - all in the United Kingdom; Assistance Publique-Hôpitaux de Paris Hôpital Bicêtre, Paris (A.L.); and Ultragenyx Pharmaceutical, Novato (M.M., C.-Y.C., A.S., E.K., J.S.M.), and University of California at San Francisco, San Francisco (A.A.P.) - both in California
| | - Javier San Martin
- From Yale University School of Medicine, New Haven, CT (T.O.C.); Shriners Hospital for Children and Division of Bone and Mineral Diseases, Department of Internal Medicine, Washington University School of Medicine, St. Louis (M.P.W.); Indiana University School of Medicine, Indianapolis (E.A.I.); University of Groningen, Groningen, the Netherlands (A.M.B.); Birmingham Children's Hospital, Birmingham (W. Högler), Royal Manchester Children's Hospital, Manchester (R.P.), and Great Ormond Street Hospital, London (W. van't Hoff) - all in the United Kingdom; Assistance Publique-Hôpitaux de Paris Hôpital Bicêtre, Paris (A.L.); and Ultragenyx Pharmaceutical, Novato (M.M., C.-Y.C., A.S., E.K., J.S.M.), and University of California at San Francisco, San Francisco (A.A.P.) - both in California
| | - Anthony A Portale
- From Yale University School of Medicine, New Haven, CT (T.O.C.); Shriners Hospital for Children and Division of Bone and Mineral Diseases, Department of Internal Medicine, Washington University School of Medicine, St. Louis (M.P.W.); Indiana University School of Medicine, Indianapolis (E.A.I.); University of Groningen, Groningen, the Netherlands (A.M.B.); Birmingham Children's Hospital, Birmingham (W. Högler), Royal Manchester Children's Hospital, Manchester (R.P.), and Great Ormond Street Hospital, London (W. van't Hoff) - all in the United Kingdom; Assistance Publique-Hôpitaux de Paris Hôpital Bicêtre, Paris (A.L.); and Ultragenyx Pharmaceutical, Novato (M.M., C.-Y.C., A.S., E.K., J.S.M.), and University of California at San Francisco, San Francisco (A.A.P.) - both in California
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11
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Tokarz D, Martins JS, Petit ET, Lin CP, Demay MB, Liu ES. Hormonal Regulation of Osteocyte Perilacunar and Canalicular Remodeling in the Hyp Mouse Model of X-Linked Hypophosphatemia. J Bone Miner Res 2018; 33:499-509. [PMID: 29083055 PMCID: PMC6005377 DOI: 10.1002/jbmr.3327] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/03/2017] [Revised: 10/14/2017] [Accepted: 10/27/2017] [Indexed: 01/07/2023]
Abstract
Osteocytes remodel their surrounding perilacunar matrix and canalicular network to maintain skeletal homeostasis. Perilacunar/canalicular remodeling is also thought to play a role in determining bone quality. X-linked hypophosphatemia (XLH) is characterized by elevated serum fibroblast growth factor 23 (FGF23) levels, resulting in hypophosphatemia and decreased production of 1,25 dihydroxyvitamin D (1,25D). In addition to rickets and osteomalacia, long bones from mice with XLH (Hyp) have impaired whole-bone biomechanical integrity accompanied by increased osteocyte apoptosis. To address whether perilacunar/canalicular remodeling is altered in Hyp mice, histomorphometric analyses of tibia and 3D intravital microscopic analyses of calvaria were performed. These studies demonstrate that Hyp mice have larger osteocyte lacunae in both the tibia and calvaria, accompanied by enhanced osteocyte mRNA and protein expression of matrix metalloproteinase 13 (MMP13) and genes classically used by osteoclasts to resorb bone, such as cathepsin K (CTSK). Hyp mice also exhibit impaired canalicular organization, with a decrease in number and branching of canaliculi extending from tibial and calvarial lacunae. To determine whether improving mineral ion and hormone homeostasis attenuates the lacunocanalicular phenotype, Hyp mice were treated with 1,25D or FGF23 blocking antibody (FGF23Ab). Both therapies were shown to decrease osteocyte lacunar size and to improve canalicular organization in tibia and calvaria. 1,25D treatment of Hyp mice normalizes osteocyte expression of MMP13 and classic osteoclast markers, while FGF23Ab decreases expression of MMP13 and selected osteoclast markers. Taken together, these studies point to regulation of perilacunar/canalicular remodeling by physiologic stimuli including hypophosphatemia and 1,25D. © 2017 American Society for Bone and Mineral Research.
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Affiliation(s)
- Danielle Tokarz
- Advanced Microscopy Program, Center for Systems Biology and Wellman Center for Photomedicine, Massachusetts General Hospital, Boston, MA, USA
- Harvard Medical School, Boston, MA, USA
| | - Janaina S Martins
- Harvard Medical School, Boston, MA, USA
- Endocrine Unit, Massachusetts General Hospital, Boston, MA, USA
| | | | - Charles P Lin
- Advanced Microscopy Program, Center for Systems Biology and Wellman Center for Photomedicine, Massachusetts General Hospital, Boston, MA, USA
- Harvard Medical School, Boston, MA, USA
| | - Marie B Demay
- Harvard Medical School, Boston, MA, USA
- Endocrine Unit, Massachusetts General Hospital, Boston, MA, USA
| | - Eva S Liu
- Harvard Medical School, Boston, MA, USA
- Endocrine Unit, Massachusetts General Hospital, Boston, MA, USA
- Division of Endocrinology, Diabetes, and Hypertension, Brigham and Women's Hospital, Boston, MA, USA
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12
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Abstract
Hereditary vitamin D-resistant rickets (HVDRR) is a rare genetic disorder caused by mutations at the level of the vitamin D receptor ( VDR) gene. The disease is characterized by refractory hypocalcemia, elevated serum levels of 1,25-dihydroxy-vitamin D, retarded growth, sparse body hair (sometimes alopecia), premature tooth loss, enlarged pulp chambers, thin dentine, and hypoplastic enamel. The aims of this study were 1) to document the dental development of children with HVDRR in association with the mutation type within the VDR and 2) to evaluate the association between dental development and the timing of and response to HVDRR treatment. Genome analysis was performed for 4 affected children (2 y 2 mo to 6 y 8 mo) under treatment with high doses of vitamin D and calcium. Longitudinal records of clinical and radiographic data on their dental development were assessed in relation to genetic profile and response to treatment. Treatment success depended on the position of the mutation within the VDR protein: children with the p.R391S mutation had a favorable outcome but maintained alopecia totalis, while 1 child with the p.H397P mutation and normal hair had no response to very high doses of vitamin D. The primary incisors, formed prenatally and first to emerge, were missing in 3 children and mobile in 1 child; parents reported loss within months posteruption. Posterior teeth were present, having erupted after treatment initiation. Hypoplastic enamel in emerging teeth was associated with late treatment onset. Mutation type in the VDR gene appears to be related to differences in the disease phenotype and response to treatment. Dental development represents an indicator of the disease process, initially protected by maternal blood levels of calcium and later restored by therapeutic supplies that normalize these levels. Knowledge Transfer Statement: Two novel mutations were associated with different HVDRR phenotypes, one of which responded positively to treatment. Early detection of the mutation should help pediatricians forecast treatment protocol and response. The results also highlight the direct relationship between dental development and blood calcium levels, underscoring the importance of early diagnosis and treatment of HVDRR to minimize the loss of primary teeth and reduce structural abnormalities of permanent teeth.
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Affiliation(s)
- A E Hanna
- 1 Division of Orthodontics and Dentofacial Orthopedics, Department of Otolaryngology and Head and Neck Surgery, American University of Beirut Medical Center, Beirut, Lebanon
| | - S Sanjad
- 2 Department of Pediatrics and Adolescent Medicine, American University of Beirut Medical Center, Beirut, Lebanon
| | - R Andary
- 3 Private practice, Aley Mount, Lebanon
| | - G Nemer
- 4 Department of Biochemistry and Molecular Genetics, American University of Beirut Medical Center, Beirut, Lebanon
| | - J G Ghafari
- 1 Division of Orthodontics and Dentofacial Orthopedics, Department of Otolaryngology and Head and Neck Surgery, American University of Beirut Medical Center, Beirut, Lebanon
- 5 School of Dentistry, Lebanese University, Beirut, Lebanon
- 6 Department of Orthodontics, School of Dental Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
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13
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Abstract
PURPOSE Here, we review the skeletal effects of pediatric muscle disorders as well as muscle impairment in pediatric bone disorders. RECENT FINDINGS When starting in utero, muscle disorders can lead to congenital multiple contractures. Pediatric-onset muscle weakness such as cerebral palsy, Duchenne muscular dystrophy, spinal muscular atrophy, or spina bifida typically are associated with small diameter of long-bone shafts, low density of metaphyseal bone, and increased fracture incidence in the lower extremities, in particular, the distal femur. Primary bone diseases can affect muscles through generic mechanisms, such as decreased physical activity or in disease-specific ways. For example, the collagen defect underlying the bone fragility of osteogenesis imperfecta may also affect muscle force generation or transmission. Transforming growth factor beta released from bone in Camurati Engelman disease may decrease muscle function. FUTURE DIRECTIONS Considering muscle-bone interactions does not only contribute to the understanding of musculoskeletal disorders but also can identify new targets for therapeutic interventions.
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Affiliation(s)
| | - Frank Rauch
- Shriners Hospital for Children, 1003 Boulevard Decarie, Montreal, QC, H4A 0A9, Canada
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14
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Kinoshita Y, Ito N, Makita N, Nangaku M, Fukumoto S. Changes in bone metabolic parameters following oral calcium supplementation in an adult patient with vitamin D-dependent rickets type 2A. Endocr J 2017; 64:589-596. [PMID: 28367941 DOI: 10.1507/endocrj.ej16-0583] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Vitamin D-dependent rickets type 2A (VDDR2A) is a rare inherited disorder with decreased tissue responsiveness to 1,25-dihydroxyvitamin D [1,25(OH)2D], caused by loss of function mutations in the vitamin D receptor (VDR) gene. Approximately 50 types of mutations have been identified so far that change amino acids in either the N-terminal DNA binding domain (DBD) or the C-terminal ligand binding domain (LBD) of the VDR protein. The degree of responsiveness to 1,25(OH)2D varies between patients with VDDR2A, which may depend on their residual VDR function. In this report, we describe a female patient with VDDR2A caused by an early stop codon (R30X) in the VDR gene that resulted in a severely truncated VDR protein. She developed alopecia and bowed legs within a year after birth and was diagnosed with rickets at the age of 2. She had been treated with active vitamin D and oral calcium supplementation until 22 years of age, when she developed secondary hyperparathyroidism and high bone turnover. The genetic diagnosis of VDDR2A promoted the discontinuation of active vitamin D treatment in favor of monotherapy with oral calcium supplementation. We observed amelioration of the secondary hyperparathyroidism and normalization of bone metabolic parameters within 6 years.
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Affiliation(s)
- Yuka Kinoshita
- Division of Nephrology & Endocrinology, Department of Medicine, the University of Tokyo Hospital, Tokyo, Japan
| | - Nobuaki Ito
- Division of Nephrology & Endocrinology, Department of Medicine, the University of Tokyo Hospital, Tokyo, Japan
| | - Noriko Makita
- Division of Nephrology & Endocrinology, Department of Medicine, the University of Tokyo Hospital, Tokyo, Japan
| | - Masaomi Nangaku
- Division of Nephrology & Endocrinology, Department of Medicine, the University of Tokyo Hospital, Tokyo, Japan
| | - Seiji Fukumoto
- Fujii Memorial Institute of Medical Sciences, Tokushima University, Tokushima, Japan
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15
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Colares Neto GP, Pereira RMR, Alvarenga JC, Takayama L, Funari MFA, Martin RM. Evaluation of bone mineral density and microarchitectural parameters by DXA and HR-pQCT in 37 children and adults with X-linked hypophosphatemic rickets. Osteoporos Int 2017; 28:1685-1692. [PMID: 28194480 DOI: 10.1007/s00198-017-3949-8] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/16/2016] [Accepted: 01/26/2017] [Indexed: 02/07/2023]
Abstract
UNLABELLED In X-linked hypophosphatemic (XLH) rickets, dual-energy X-ray absorptiometry (DXA) measurements must be analyzed with caution. High-resolution peripheral quantitative computed tomography (HR-pQCT) analysis suggested that XLH primarily affects the cancellous compartment, with the tibia more affected than the radius. Effective treatment of XLH appears to positively affect bone mineralization, mainly in the bone cortex. INTRODUCTION The purpose of this study is to evaluate bone mineral density (BMD) and microarchitecture in 37 patients (13 children and 24 adults) with XLH confirmed by PHEX mutations from a tertiary center compared to healthy controls. METHODS Areal BMD (aBMD) was evaluated by DXA, whereas volumetric BMD (vBMD) and microarchitectural parameters were analyzed by HR-pQCT. RESULTS Adult XLH patients had higher lumbar aBMD (p < 0.01) than the controls. At the radius, the vBMD was similar between XLH patients and controls. At the tibia, XLH patients had lower total vBMD (p = 0.04), likely resulting from decreased trabecular vBMD (p < 0.01), and this difference was observed in the children and adult groups. Analysis based on metabolic status showed that the adult XLH patients with non-compensated disease had lower cortical vBMD at the tibia than the compensated XLH patients (p = 0.03). The microarchitectural differences at the radius and tibia included lower trabecular number (p < 0.01), greater trabecular separation (p < 0.01), and higher trabecular network inhomogeneity (p < 0.01) in XLH patients compared to their controls. At the radius, adults exhibited greater trabecular deficits than were seen in children. CONCLUSIONS In XLH patients, DXA measurements must be analyzed with caution due to the interference of anatomic and anthropometric factors. HR-pQCT analysis suggested that XLH primarily affects the cancellous compartment, with the tibia more affected than the radius. Effective treatment of XLH appears to positively affect bone mineralization, mainly in the bone cortex.
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Affiliation(s)
- G P Colares Neto
- Osteometabolic Disorders Unit, Endocrinology Division, Hospital das Clínicas da Universidade de São Paulo, Av. Dr. Enéas de Carvalho Aguiar, 155 - PAMB, 8° andar, Bloco 3, São Paulo, SP, 05403-900, Brazil
- Hormone and Molecular Genetics Laboratory (LIM/42), Endocrinology Division, Hospital das Clínicas da Universidade de São Paulo, Av. Dr. Enéas de Carvalho Aguiar, 155 - PAMB, 2° andar, Bloco 6, São Paulo, SP, 05403-900, Brazil
| | - R M R Pereira
- Bone Metabolism Laboratory (LIM/17), Rheumatology Division, Faculdade de Medicina da Universidade de São Paulo, Av. Dr. Arnaldo, 455, 3° andar, Sala 3193, São Paulo, SP, 01246-903, Brazil
| | - J C Alvarenga
- Bone Metabolism Laboratory (LIM/17), Rheumatology Division, Faculdade de Medicina da Universidade de São Paulo, Av. Dr. Arnaldo, 455, 3° andar, Sala 3193, São Paulo, SP, 01246-903, Brazil
| | - L Takayama
- Bone Metabolism Laboratory (LIM/17), Rheumatology Division, Faculdade de Medicina da Universidade de São Paulo, Av. Dr. Arnaldo, 455, 3° andar, Sala 3193, São Paulo, SP, 01246-903, Brazil
| | - M F A Funari
- Hormone and Molecular Genetics Laboratory (LIM/42), Endocrinology Division, Hospital das Clínicas da Universidade de São Paulo, Av. Dr. Enéas de Carvalho Aguiar, 155 - PAMB, 2° andar, Bloco 6, São Paulo, SP, 05403-900, Brazil
| | - R M Martin
- Osteometabolic Disorders Unit, Endocrinology Division, Hospital das Clínicas da Universidade de São Paulo, Av. Dr. Enéas de Carvalho Aguiar, 155 - PAMB, 8° andar, Bloco 3, São Paulo, SP, 05403-900, Brazil.
- Hormone and Molecular Genetics Laboratory (LIM/42), Endocrinology Division, Hospital das Clínicas da Universidade de São Paulo, Av. Dr. Enéas de Carvalho Aguiar, 155 - PAMB, 2° andar, Bloco 6, São Paulo, SP, 05403-900, Brazil.
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16
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Abstract
X-linked hypophosphatemia (XLH) is a group of rare disorders caused by defective proximal tubular reabsorption of phosphate. Mutations in the PHEX gene are responsible for the majority of cases. There are very few reports of long-term complications of XLH other than skeletal and dental diseases. The aim of this study was to identify the phenotypic presentation of XLH during adulthood including complications other than skeletal and dental diseases. The clinical and biochemical phenotype of 22 adult patients with a PHEX gene mutation were examined retrospectively from their medical records. 6 patients had hypertension. The average age of hypertension onset was 29.0 years. Secondary hyperparathyroidism preceded the development of hypertension in 5 patients. 1 patient developed tertiary hyperparathyroidism. 15 patients had nephrocalcinosis. 2 patients had chronic renal dysfunction. Patients with hypertension had a significantly lower eGFR (p=0.010) compared to patients without hypertension. No significant difference was found in any other parameters. To examine the genotype-phenotype correlation, 10 adult males were chosen for analysis. No significant genotype-phenotype correlation analysis was revealed in any of the complications. However, there was a possibility that the age at nephrocalcinosis onset was younger in the non-missense mutation group than in the missense mutation group (p=0.063). This study corroborated the view that early-onset hypertension could be one of the characteristic complications seen in XLH patients. Considering the limited number of our patients, further study is necessary to address a potential cause of hypertension. XLH patients require careful lifelong treatment.
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Affiliation(s)
- Yoshie Nakamura
- Division of Genetic Research, Tokyo Metropolitan Children's Medical Center, Tokyo 183-8561, Japan
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Che H, Roux C, Etcheto A, Rothenbuhler A, Kamenicky P, Linglart A, Briot K. Impaired quality of life in adults with X-linked hypophosphatemia and skeletal symptoms. Eur J Endocrinol 2016; 174:325-33. [PMID: 26783348 DOI: 10.1530/eje-15-0661] [Citation(s) in RCA: 96] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
OBJECTIVE Adults with X-linked hypophosphatemia (XLH) may suffer from skeletal symptoms leading to functional disability. No data on their quality of life (QoL) have been reported so far. Our objectives were to evaluate the QoL and its determinants in XLH adults. PATIENTS AND METHODS We conducted a prospective study in XLH adults, who consulted for musculoskeletal symptoms between 2013 and 2014. We assessed their QoL using HAQ, RAPID3 and SF36, and analysed the variables associated with low QoL. We compared their QoL to that of patients affected with axial spondyloarthritis (ax-SpA) (paired on age and gender), a rheumatologic disorder with a known low QoL. RESULTS Fifty-two XLH adults (37 women (71.1%); mean age 41.8±13.3 years) were included; 44 (84.6%) patients had an altered QoL. Increased age and presence of structural lesions were significantly associated with worse QoL (HAQ, RAPID3) (P<0.05). Presence of enthesopathies was significantly associated with worse RAPID3 (OR=4.45 (1.09-18.29), P=0.038). Treatment with phosphate supplements and vitamin D in XLH adults were significantly associated with a better SF36-mental component score (OR=0.14 (0.03-0.57), P=0.007 and OR=0.26 (0.07-0.98), P=0.047 respectively). QoL was significantly worse in XLH than in ax-SpA adults (VAS pain, SF36-PCS, RAPID3) (P<0.05). CONCLUSION Our study showed i) QoL of XLH adults is altered and significantly worse than that of ax-SpA patients (VAS pain, SF36-PCS and RAPID3), ii) structural lesions and especially enthesopathies are associated with a worse QoL and iii) treatment using phosphate supplements and/or vitamin D is associated with a better mental health score.
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MESH Headings
- Adult
- Case-Control Studies
- Cohort Studies
- Familial Hypophosphatemic Rickets/diagnostic imaging
- Familial Hypophosphatemic Rickets/epidemiology
- Familial Hypophosphatemic Rickets/physiopathology
- Female
- Fractures, Bone/diagnostic imaging
- Fractures, Bone/epidemiology
- Fractures, Bone/physiopathology
- Genetic Diseases, X-Linked/diagnostic imaging
- Genetic Diseases, X-Linked/epidemiology
- Genetic Diseases, X-Linked/physiopathology
- Humans
- Male
- Middle Aged
- Osteoarthritis/diagnostic imaging
- Osteoarthritis/epidemiology
- Osteoarthritis/physiopathology
- Osteoarthritis, Hip/diagnostic imaging
- Osteoarthritis, Hip/epidemiology
- Osteoarthritis, Hip/physiopathology
- Osteoarthritis, Knee/diagnostic imaging
- Osteoarthritis, Knee/epidemiology
- Osteoarthritis, Knee/physiopathology
- Osteoarthritis, Spine/diagnostic imaging
- Osteoarthritis, Spine/epidemiology
- Osteoarthritis, Spine/physiopathology
- Prospective Studies
- Quality of Life
- Radiography
- Rheumatic Diseases/diagnostic imaging
- Rheumatic Diseases/epidemiology
- Spondylarthritis/diagnostic imaging
- Spondylarthritis/epidemiology
- Spondylarthritis/physiopathology
- Spondylarthropathies/diagnostic imaging
- Spondylarthropathies/epidemiology
- Spondylarthropathies/physiopathology
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Affiliation(s)
- Hélène Che
- Department of RheumatologyFrench Reference Center for Genetic Bone Diseases, Cochin Hospital, Assistance Publique- Hôpitaux de Paris, 27 rue du Faubourg Saint Jacques, 75014 Paris, FranceINSERM U1153Paris, FranceParis-Descartes UniversityParis, FranceINSERM U1169Paris Sud University, Assistance Publique- Hôpitaux de Paris, French Reference Center for Rare Disorders of the Mineral Metabolism, Department of Endocrinology and Diabetology for Children, Bicêtre Hospital, 78 rue du Général Leclerc, 94270 Le Kremlin Bicêtre, France
| | - Christian Roux
- Department of RheumatologyFrench Reference Center for Genetic Bone Diseases, Cochin Hospital, Assistance Publique- Hôpitaux de Paris, 27 rue du Faubourg Saint Jacques, 75014 Paris, FranceINSERM U1153Paris, FranceParis-Descartes UniversityParis, FranceINSERM U1169Paris Sud University, Assistance Publique- Hôpitaux de Paris, French Reference Center for Rare Disorders of the Mineral Metabolism, Department of Endocrinology and Diabetology for Children, Bicêtre Hospital, 78 rue du Général Leclerc, 94270 Le Kremlin Bicêtre, France Department of RheumatologyFrench Reference Center for Genetic Bone Diseases, Cochin Hospital, Assistance Publique- Hôpitaux de Paris, 27 rue du Faubourg Saint Jacques, 75014 Paris, FranceINSERM U1153Paris, FranceParis-Descartes UniversityParis, FranceINSERM U1169Paris Sud University, Assistance Publique- Hôpitaux de Paris, French Reference Center for Rare Disorders of the Mineral Metabolism, Department of Endocrinology and Diabetology for Children, Bicêtre Hospital, 78 rue du Général Leclerc, 94270 Le Kremlin Bicêtre, France Department of RheumatologyFrench Reference Center for Genetic Bone Diseases, Cochin Hospital, Assistance Publique- Hôpitaux de Paris, 27 rue du Faubourg Saint Jacques, 75014 Paris, FranceINSERM U1153Paris, FranceParis-Descartes UniversityParis, FranceINSERM U1169Paris Sud University, Assistance Publique- Hôpitaux de Paris, French Reference Center for Rare Disorders of the Mineral Metabolism, Department of Endocrinology and Diabetology for Children, Bicêtre Hospital, 78 rue du Général Leclerc, 94270 Le Kremlin Bicêtre, France
| | - Adrien Etcheto
- Department of RheumatologyFrench Reference Center for Genetic Bone Diseases, Cochin Hospital, Assistance Publique- Hôpitaux de Paris, 27 rue du Faubourg Saint Jacques, 75014 Paris, FranceINSERM U1153Paris, FranceParis-Descartes UniversityParis, FranceINSERM U1169Paris Sud University, Assistance Publique- Hôpitaux de Paris, French Reference Center for Rare Disorders of the Mineral Metabolism, Department of Endocrinology and Diabetology for Children, Bicêtre Hospital, 78 rue du Général Leclerc, 94270 Le Kremlin Bicêtre, France
| | - Anya Rothenbuhler
- Department of RheumatologyFrench Reference Center for Genetic Bone Diseases, Cochin Hospital, Assistance Publique- Hôpitaux de Paris, 27 rue du Faubourg Saint Jacques, 75014 Paris, FranceINSERM U1153Paris, FranceParis-Descartes UniversityParis, FranceINSERM U1169Paris Sud University, Assistance Publique- Hôpitaux de Paris, French Reference Center for Rare Disorders of the Mineral Metabolism, Department of Endocrinology and Diabetology for Children, Bicêtre Hospital, 78 rue du Général Leclerc, 94270 Le Kremlin Bicêtre, France
| | - Peter Kamenicky
- Department of RheumatologyFrench Reference Center for Genetic Bone Diseases, Cochin Hospital, Assistance Publique- Hôpitaux de Paris, 27 rue du Faubourg Saint Jacques, 75014 Paris, FranceINSERM U1153Paris, FranceParis-Descartes UniversityParis, FranceINSERM U1169Paris Sud University, Assistance Publique- Hôpitaux de Paris, French Reference Center for Rare Disorders of the Mineral Metabolism, Department of Endocrinology and Diabetology for Children, Bicêtre Hospital, 78 rue du Général Leclerc, 94270 Le Kremlin Bicêtre, France
| | - Agnès Linglart
- Department of RheumatologyFrench Reference Center for Genetic Bone Diseases, Cochin Hospital, Assistance Publique- Hôpitaux de Paris, 27 rue du Faubourg Saint Jacques, 75014 Paris, FranceINSERM U1153Paris, FranceParis-Descartes UniversityParis, FranceINSERM U1169Paris Sud University, Assistance Publique- Hôpitaux de Paris, French Reference Center for Rare Disorders of the Mineral Metabolism, Department of Endocrinology and Diabetology for Children, Bicêtre Hospital, 78 rue du Général Leclerc, 94270 Le Kremlin Bicêtre, France
| | - Karine Briot
- Department of RheumatologyFrench Reference Center for Genetic Bone Diseases, Cochin Hospital, Assistance Publique- Hôpitaux de Paris, 27 rue du Faubourg Saint Jacques, 75014 Paris, FranceINSERM U1153Paris, FranceParis-Descartes UniversityParis, FranceINSERM U1169Paris Sud University, Assistance Publique- Hôpitaux de Paris, French Reference Center for Rare Disorders of the Mineral Metabolism, Department of Endocrinology and Diabetology for Children, Bicêtre Hospital, 78 rue du Général Leclerc, 94270 Le Kremlin Bicêtre, France Department of RheumatologyFrench Reference Center for Genetic Bone Diseases, Cochin Hospital, Assistance Publique- Hôpitaux de Paris, 27 rue du Faubourg Saint Jacques, 75014 Paris, FranceINSERM U1153Paris, FranceParis-Descartes UniversityParis, FranceINSERM U1169Paris Sud University, Assistance Publique- Hôpitaux de Paris, French Reference Center for Rare Disorders of the Mineral Metabolism, Department of Endocrinology and Diabetology for Children, Bicêtre Hospital, 78 rue du Général Leclerc, 94270 Le Kremlin Bicêtre, France
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18
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Abstract
CONTEXT ASARM-peptides are substrates and ligands for PHEX, the gene responsible for X-linked hypophosphatemic rickets (HYP). PHEX binds to the DMP1-ASARM-motif to form a trimeric-complex with α5β3-integrin on the osteocyte surface and this suppresses FGF23 expression. ASARM-peptide disruption of this complex increases FGF23 expression. We used a 4.2kDa peptide (SPR4) that binds to ASARM-peptide and ASARM-motif to study DMP1-PHEX interactions and to assess SPR4 for treating inherited hypophosphatemic rickets. DESIGN Subcutaneously transplanted osmotic pumps were used to infuse SPR4-peptide or vehicle into wild-type mice (WT) and HYP-mice for 4 weeks. RESULTS Asymmetrically distributed mineralization defects occurred with WT-SPR4 femurs. Specifically, SPR4 induced negative effects on trabecular bone and increased bone volume and mineralization in cortical-bone. Markedly increased sclerostin and reduced active β-catenin occurred with HYP mice. SPR4-infusion suppressed sclerostin and increased active β-catenin in WT and HYP mice and improved HYP-mice trabecular mineralization defects but not cortical mineralization defects. CONCLUSIONS SPR4-peptide has bimodal activity and acts by: (1) preventing DMP1 binding to PHEX and (2) sequestering an inhibitor of DMP1-PHEX binding, ASARM-peptide. In PHEX defective HYP-mice the second pathway predominates. Although SPR4-peptide improved trabecular calcification defects, decreased sclerostin and increased active β-catenin it did not correct HYP-mice cortical mineralization defects on a normal phosphate diet. Thus, for inherited hypophosphatemic rickets patients on a normal phosphate diet, SPR4-peptide is not a useful therapeutic.
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Affiliation(s)
- Lesya V Zelenchuk
- The Kidney Institute, Kansas University Medical Center, Kansas City, KS, USA
| | - Anne-Marie Hedge
- The Kidney Institute, Kansas University Medical Center, Kansas City, KS, USA
| | - Peter S N Rowe
- The Kidney Institute, Kansas University Medical Center, Kansas City, KS, USA.
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Japaridze NV, Margvelashvili VV, Shengelia MI, Chigladze TT, Kalandadze MN. Periodontal diseases in patients with vitamin D-resistant rickets. Georgian Med News 2015:23-26. [PMID: 25802443] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
OBJECTIVE To define the risk of development of periodontal diseases at vitamin D-resistant rickets. The material for the study was based on the data from 13 children of 0-18 years with vitamin D-resistant rickets (I group), 68 children with vitamin D-dependent rickets (II group), and the control group included 61 children of the same ages. The patients were divided into 3 age groups: I group of 0-5 years (deciduous/milk teeth occlusion), II group of 6-12 of years (mixed bite), III group of 13-18 years (permanent occlusion). For the qualitative data the differences between the groups were detected by using F criteria but for the quantitative data the differences between the groups were detected by Student's t test for independent selection. Mathematical processing was performed using statistical software SPSS-22. In all three groups the gingivitis of mild and moderate forms were fixed, among them acute course was revealed only in the group of vitamin D-resistant rickets. The rate of chronic, local, catarrhal and generalized gingivitis in the group of vitamin D-resistant rickets was reliably higher in comparison with both vitamin D-dependant rickets and control groups. In addition, a mild form of periodontitis with chronic course was revealed in all three groups the rate of which was reliably higher in the group of vitamin D-resistant rickets comparing with the ones of vitamin D-dependant rickets and control groups. CONCLUSION the rate of inflammatory periodontal diseases in children with vitamin D-resistant rickets is higher than in children with vitamin D-dependent rickets and the control groups.
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20
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Miyai K, Onishi T, Kashimada K, Hasegawa Y. Urinary calcium to creatinine ratio: a potential marker of secondary hyperparathyroidism in patients with vitamin D-dependent rickets type 1A. Endocr J 2015; 62:61-8. [PMID: 25284246 DOI: 10.1507/endocrj.ej14-0085] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Patients with vitamin D-dependent rickets type 1A (VDDR1A) are usually treated with alfacalcidol, an analog of vitamin D. Around puberty, an increased dose of alfacalcidol is recommended for these patients to avoid hypocalcemia and secondary hyperparathyroidism. However, no indicators of secondary hyperparathyroidism except for PTH are presently known. The aim of this study is to evaluate whether urinary calcium to creatinine ratio (U-Ca/Cr) is useful as a biomarker of secondary hyperparathyroidism in VDDR1A patients in order to determine the proper dose of alfacalcidol. Two brothers with VDDR1A were recruited who had null mutations of CYP27B1 which encodes 1-alpha-hydroxylase of vitamin D. We investigated the relationship between U-Ca/Cr and intact-PTH around puberty when the brothers showed hypocalcemia with secondary hyperparathyroidism. The results were compared to those of five patients with vitamin D deficiency (VDD). As a result, high intact-PTH levels were observed when U-Ca/Cr decreased to less than 0.1 (mg/mg) in both VDDR1A brothers. This relationship was also observed in the VDD patients. However, it is necessary to take into account body calcium status, either in depletion or in excess, to accurately evaluate the relationship between U-Ca/Cr and secondary hyperparathyroidism. First, low U-Ca/Cr was detected in situations with calcium depletion without hyperparathyroidism in the VDDR1A patients. Second, high U-Ca/Cr with hyperparathyroidism could be detected theoretically in a condition of excess calcium supply. In conclusion, a U-Ca/Cr ratio of less than 0.1 (mg/mg) in VDDR1A patients is useful to accurately evaluate calcium depletion and secondary hyperparathyroidism.
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Affiliation(s)
- Kentaro Miyai
- Division of Endocrinology and Metabolism, Tokyo Metropolitan Children's Medical Center, Tokyo 183-8561, Japan; Department of Pediatrics and Developmental Biology, Tokyo Medical and Dental University, Tokyo 113-8510, Japan
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Carpenter TO, Imel EA, Ruppe MD, Weber TJ, Klausner MA, Wooddell MM, Kawakami T, Ito T, Zhang X, Humphrey J, Insogna KL, Peacock M. Randomized trial of the anti-FGF23 antibody KRN23 in X-linked hypophosphatemia. J Clin Invest 2014; 124:1587-97. [PMID: 24569459 DOI: 10.1172/jci72829] [Citation(s) in RCA: 206] [Impact Index Per Article: 20.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2013] [Accepted: 12/17/2013] [Indexed: 12/25/2022] Open
Abstract
BACKGROUND X-linked hypophosphatemia (XLH) is the most common heritable form of rickets and osteomalacia. XLH-associated mutations in phosphate-regulating endopeptidase (PHEX) result in elevated serum FGF23, decreased renal phosphate reabsorption, and low serum concentrations of phosphate (inorganic phosphorus, Pi) and 1,25-dihydroxyvitamin D [1,25(OH)2D]. KRN23 is a human anti-FGF23 antibody developed as a potential treatment for XLH. Here, we have assessed the safety, tolerability, pharmacokinetics (PK), pharmacodynamics (PD), and immunogenicity of KRN23 following a single i.v. or s.c. dose of KRN23 in adults with XLH. METHODS Thirty-eight XLH patients were randomized to receive a single dose of KRN23 (0.003-0.3 mg/kg i.v. or 0.1-1 mg/kg s.c.) or placebo. PK, PD, immunogenicity, safety, and tolerability were assessed for up to 50 days. RESULTS KRN23 significantly increased the maximum renal tubular threshold for phosphate reabsorption (TmP/GFR), serum Pi, and 1,25(OH)2D compared with that of placebo (P<0.01). The maximum serum Pi concentration occurred later following s.c. dosing (8-15 days) compared with that seen with i.v. dosing (0.5-4 days). The effect duration was dose related and persisted longer in patients who received s.c. administration. Changes from baseline in TmP/GFR, serum Pi, and serum 1,25(OH)2D correlated with serum KRN23 concentrations. The mean t1/2 of KRN23 was 8-12 days after i.v. administration and 13-19 days after s.c. administration. Patients did not exhibit increased nephrocalcinosis or develop hypercalciuria, hypercalcemia, anti-KRN23 antibodies, or elevated serum parathyroid hormone (PTH) or creatinine. CONCLUSION KRN23 increased TmP/GFR, serum Pi, and serum 1,25(OH)2D. The positive effect of KR23 on serum Pi and its favorable safety profile suggest utility for KRN23 in XLH patients. Trial registration. Clinicaltrials.gov NCT00830674. Funding. Kyowa Hakko Kirin Pharma, Inc.
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Abstract
PURPOSE OF REVIEW The purpose of this study is to review the regulation of phosphate and recent progress in fibroblast growth factor-23 (FGF-23), a key phosphate regulatory hormone. RECENT FINDINGS Phosphate is required for mineralization of bone, muscle strength and a host of biologic functions. Phosphate is sensed by bone that responds with secretion of FGF-23. The major action of FGF-23 is to stimulate phosphaturia. Feedback loops between FGF-23, 1,25-dihydroxyvitamin D3 and parathyroid hormone maintain phosphate homeostasis. Information about FGF-23 has accumulated from studies in patients with oncogenic osteomalacia and inherited disorders of phosphate wasting rickets that explains the pathophysiology. Exciting new discoveries have highlighted FGF-23 as an independent risk factor for cardiovascular disease in patients with chronic kidney disease. The phosphate sensor triggering FGF-23 production remains to be identified. SUMMARY Derangements in FGF-23 production, half-life or downstream response are responsible for several disorders of phosphate wasting, rickets and oncogenic osteomalacia. Very high levels of FGF-23 in renal failure are an independent risk for cardiovascular disease.
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Affiliation(s)
- Mark S Nanes
- Department of Medicine, Atlanta VA Medical Center and Division of Endocrinology, Lipids, and Metabolism, Emory University School of Medicine, Atlanta, Georgia, USA
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23
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McKee MD, Hoac B, Addison WN, Barros NM, Millán JL, Chaussain C. Extracellular matrix mineralization in periodontal tissues: Noncollagenous matrix proteins, enzymes, and relationship to hypophosphatasia and X-linked hypophosphatemia. Periodontol 2000 2013; 63:102-22. [PMID: 23931057 PMCID: PMC3766584 DOI: 10.1111/prd.12029] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/15/2012] [Indexed: 12/26/2022]
Abstract
As broadly demonstrated for the formation of a functional skeleton, proper mineralization of periodontal alveolar bone and teeth - where calcium phosphate crystals are deposited and grow within an extracellular matrix - is essential for dental function. Mineralization defects in tooth dentin and cementum of the periodontium invariably lead to a weak (soft or brittle) dentition in which teeth become loose and prone to infection and are lost prematurely. Mineralization of the extremities of periodontal ligament fibers (Sharpey's fibers) where they insert into tooth cementum and alveolar bone is also essential for the function of the tooth-suspensory apparatus in occlusion and mastication. Molecular determinants of mineralization in these tissues include mineral ion concentrations (phosphate and calcium), pyrophosphate, small integrin-binding ligand N-linked glycoproteins and matrix vesicles. Amongst the enzymes important in regulating these mineralization determinants, two are discussed at length here, with clinical examples given, namely tissue-nonspecific alkaline phosphatase and phosphate-regulating gene with homologies to endopeptidases on the X chromosome. Inactivating mutations in these enzymes in humans and in mouse models lead to the soft bones and teeth characteristic of hypophosphatasia and X-linked hypophosphatemia, respectively, where the levels of local and systemic circulating mineralization determinants are perturbed. In X-linked hypophosphatemia, in addition to renal phosphate wasting causing low circulating phosphate levels, phosphorylated mineralization-regulating small integrin-binding ligand N-linked glycoproteins, such as matrix extracellular phosphoglycoprotein and osteopontin, and the phosphorylated peptides proteolytically released from them, such as the acidic serine- and aspartate-rich-motif peptide, may accumulate locally to impair mineralization in this disease.
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Affiliation(s)
- Marc D. McKee
- Faculty of Dentistry, McGill University, Montreal, QC, Canada
- Department of Anatomy and Cell Biology, Faculty of Dentistry, McGill University, Montreal, QC, Canada
| | - Betty Hoac
- Faculty of Dentistry, McGill University, Montreal, QC, Canada
| | - William N. Addison
- Department of Oral Medicine, Infection and Immunity, Harvard University School of Dental Medicine, Boston, MA, USA
| | - Nilana M.T. Barros
- Departamento de Biofísica, Universidade Federal de São Paulo, São Paulo, SP, Brasil, and Departamento de Ciências Exatas e da Terra, Universidade Federal de São Paulo, Diadema, SP, Brasil
| | - José Luis Millán
- Sanford Children's Health Research Center, Sanford-Burnham Medical Research Institute, La Jolla, CA, USA
| | - Catherine Chaussain
- EA 2496, UFR Odontologie, University Paris Descartes PRES Sorbonne Paris Cité; AP-HP: Odontology Department Bretonneau, Paris and Centre de Référence des Maladies Rares du Métabolisme du Phosphore et du Calcium, Kremlin Bicêtre, France
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Tournis S, Koromila T, Chatzistamatas N, Droggaris M, Zafeiris C, Makris K, Marketou H, Papaioannou N, Kollia P, Gazi S. Hip fracture leading to the diagnosis of autosomal dominant hypophosphatemic rickets. A case report. J Musculoskelet Neuronal Interact 2013; 13:391-394. [PMID: 23989261] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Affiliation(s)
- S Tournis
- Laboratory for Research of Musculoskeletal System Theodoros Garofalidis, University of Athens, KAT Hospital, 10 Athinas Str., Athens, Greece.
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Beck-Nielsen SS, Brixen K, Gram J, Mølgaard C. High bone mineral apparent density in children with X-linked hypophosphatemia. Osteoporos Int 2013; 24:2215-21. [PMID: 23389694 DOI: 10.1007/s00198-013-2286-9] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/06/2012] [Accepted: 01/07/2013] [Indexed: 10/27/2022]
Abstract
UNLABELLED Bone mineral apparent density (BMAD) in children with X-linked hypophosphatemia (XLH) was evaluated, as they are unlikely to have extra-skeletal ossifications contributing to the elevated bone mineral density of the spine in adult patients. Children with XLH also had significantly higher BMAD of the spine compared to femoral neck. INTRODUCTION BMAD obtained by dual-energy X-ray absorptiometry scans in children with XLH was evaluated, as they are unlikely to have the extra-skeletal ossifications contributing to the elevated bone mineral density of the spine in adult patients. METHODS A total of 15 children with biochemically and genetically verified XLH were recruited. Anthropometric measurements were performed, and to correct for the short stature (small bones), the BMAD of the spine and the femoral neck was evaluated. RESULTS Z-scores of BMAD of the spine (mean (95 % CI); 2.0 (1.3-2.7); p < 0.001) were significantly elevated compared to reference children. Z-scores of the femoral neck (1.0 (-0.0 to 2.1); p = 0.059) tended to be elevated. Spine Z-scores were significantly higher than the Z-scores of the femoral neck, (paired t test, p = 0.02). BMAD of the spine was evaluated according to the Molgaard's approach; XLH children had normal bone size of the spine for age due to a normal sitting height Z-score of -0.4 (-1.0 to 0.1); p = 0.1. Z-scores of bone mineral content (BMC) of the spine for bone area were elevated (1.4 (0.8-2.1); p < 0.001). No reference data were available to allow evaluation of the BMAD of the femoral neck by the Molgaard's approach. CONCLUSIONS Children with XLH have an increased BMAD and a high BMC for bone area at the lumbar spine, and this was due to causes other than extra-skeletal ossifications and corrected for bone size. The BMAD of the spine was significantly higher compared to the femoral neck.
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Affiliation(s)
- S S Beck-Nielsen
- Institute of Clinical Research, University of Southern Denmark, Winsløwparken 19.3, 5000, Odense C, Denmark.
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Abstract
CONTEXT We recently found that patients with X-linked hypophosphatemic rickets (XLH) have a muscle function deficit in the lower extremities. As muscle force and bone mass are usually closely related, we hypothesized that patients with XLH could also have a bone mass deficit in the lower extremities. OBJECTIVE The study objective was to assess the muscle-bone relationship in the lower extremities of patients with XLH. SETTING The study was carried out in the outpatients department of a pediatric orthopedic hospital. PATIENTS AND OTHER PARTICIPANTS Thirty individuals with XLH (6 to 60 y; 9 male patients) and 30 age- and gender-matched controls participated. MAIN OUTCOME MEASURES Calf muscle size and density as well as tibia bone mass and geometry were assessed by peripheral quantitative computed tomography. Muscle function was evaluated as peak force in the multiple 2-legged hopping test. RESULTS Muscle force was significantly lower in XLH patients than in controls but muscle cross-sectional area did not differ (after adjustment for tibia length). External bone size, expressed as total bone cross-sectional area, was higher in the XLH group than in controls. The XLH cohort also had statistically significantly higher bone mineral content. CONCLUSIONS Patients with XLH have increased bone mass and size at the distal tibia despite muscle function deficits.
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Affiliation(s)
- Louis-Nicolas Veilleux
- Shriners Hospital for Children and Department of Pediatrics, McGill University, Montréal, Québec, Canada.
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Cheung M, Roschger P, Klaushofer K, Veilleux LN, Roughley P, Glorieux FH, Rauch F. Cortical and trabecular bone density in X-linked hypophosphatemic rickets. J Clin Endocrinol Metab 2013; 98:E954-61. [PMID: 23533226 DOI: 10.1210/jc.2012-4133] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
CONTEXT X-linked hypophosphatemic rickets is caused by mutations in PHEX. Even though the disease is characterized by disordered skeletal mineralization, detailed bone densitometric studies are lacking. OBJECTIVE The aim of the study was to assess volumetric bone mineral density (vBMD) in X-linked hypophosphatemic rickets using forearm peripheral quantitative computed tomography. SETTING The study was conducted in the metabolic bone clinic of a pediatric orthopedic hospital. PATIENTS Thirty-four patients (age, 6 to 60 years; 24 female) with PHEX mutations were studied, of whom 7 children (age, 6 to 11 years) were actively being treated with calcitriol and phosphate supplementation. Twenty-one patients (age, 16 to 40 years) had received the same therapy before but had discontinued the treatment; 6 patients (age, 12 to 60 years) had never received this treatment. MAIN OUTCOME MEASURES Trabecular and cortical vBMD of the radius. RESULTS Trabecular vBMD was elevated (mean age-specific and sex-specific z-score: +1.0) when all patients were analyzed together, due to very high results in currently treated patients (mean z-score: +2.4) and slightly above-average mean values in the other patients. Cortical vBMD was low when the entire cohort was analyzed together (mean z-score: -3.3), but was higher in currently treated patients (mean z-score: -1.3) than in patients who had discontinued therapy (mean z-score: -3.8) or who had never been treated (mean z-score: -4.1). CONCLUSIONS Patients with PHEX mutations have elevated trabecular vBMD at the distal radius while receiving calcitriol and phosphate supplementation, but low cortical vBMD at the radius diaphysis. Low cortical vBMD presumably reflects the underlying mineralization defect that is not entirely corrected by current treatment approaches.
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Affiliation(s)
- Moira Cheung
- Shriners Hospital for Children and Department of Pediatrics, McGill University, Montreal, Quebec, Canada H3G 1A6
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Seitz S, Rendenbach C, Barvencik F, Streichert T, Jeschke A, Schulze J, Amling M, Schinke T. Retinol deprivation partially rescues the skeletal mineralization defects of Phex-deficient Hyp mice. Bone 2013; 53:231-8. [PMID: 23266491 DOI: 10.1016/j.bone.2012.12.009] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/09/2012] [Revised: 12/10/2012] [Accepted: 12/12/2012] [Indexed: 12/24/2022]
Abstract
X-linked hypophosphatemic rickets (XLH) is a genetic disorder caused by mutational inactivation of the PHEX gene, encoding a transmembrane endopeptidase expressed in osteoblasts. Since several experiments involving Phex-deficient Hyp mice have demonstrated that an increased expression of Fgf23 in osteoblasts is causative for the renal phosphate loss characteristic of XLH, we performed genome-wide expression analysis to compare differentiated osteoblasts from wildtype and Hyp mice. Here we did not only observe the expected increase of Fgf23 expression in the latter ones, but also a differential expression of genes that are either induced by or involved in retinoic acid signaling, which led us to analyze whether dietary retinol deprivation would influence the phenotype of Hyp mice. Unexpectedly, feeding a retinol-free diet resulted in a partial rescue of the growth plate and bone mineralization defects in 6 weeks old Hyp mice. When we fed the same diet for 24 weeks the amount of non-mineralized bone matrix (osteoid) was reduced by more than 70%, although phosphate homeostasis was unaffected. In contrast, a dietary normalization of serum phosphate levels in Hyp mice reduced the osteoid amount by less than 30%, thereby demonstrating a previously unknown impact of retinol on the cell-autonomous mineralization defect of Phex-deficient osteoblasts.
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Affiliation(s)
- Sebastian Seitz
- Department of Osteology and Biomechanics, University Medical Center Hamburg Eppendorf, Hamburg 20246, Germany
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29
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de Morais OO, Costa LO, Shinzato DH, Wiziack NDC, Hans-Filho G. Phacomatosis pigmentokeratotica--a patient with hypophosphatemic rickets. Skinmed 2013; 11:125-128. [PMID: 23745233] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
The epidermal naevus syndrome (ENS) is a sporadic condition characterized by congenital epidermal naevi associated with anomalies in other organ systems, most commonly the central nervous system and skeleton. We report a case of ENS presenting hypophosphataemic rickets resistant to traditional therapeutic agents.
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Sarkar S, Mondal R, Banerjee I, Sabui T. Type II vitamin D-dependent rickets with diabetic ketoacidosis. J Pediatr Endocrinol Metab 2013; 26:941-3. [PMID: 23729614 DOI: 10.1515/jpem-2013-0137] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/07/2013] [Accepted: 04/22/2013] [Indexed: 11/15/2022]
Abstract
The high prevalence of vitamin D deficiency in relation to diabetes mellitus is well reported in the literature. However, type I diabetes mellitus (T1DM) in association with resistant rickets is extremely rare and reported in only one previous case. The authors describe here a case of type II vitamin D-dependent rickets (VDDR type II) in a 10-year-old Indian girl who presented with diabetic ketoacidosis (DKA). DKA as a presenting manifestation of T1DM in a patient with VDDR type II has never been reported before in worldwide literature.
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Abstract
PURPOSE OF REVIEW Hereditary 1,25-dihydroxyvitamin-D [1,25(OH)(2)D(3)]-resistant rickets (HVDRR) is a rare genetic disease caused by generalized resistance to 1,25(OH)(2)D(3). Less than 100 cases are reported in the literature. These patients provide an experiment by nature enabling us to understand the role of vitamin D, especially in light of the ongoing debate concerning normal vitamin D levels and the supplement dosage that should be recommended. This article summarizes the role of vitamin D in calcium absorption, rennin-angiotensin system (RAS), and cardiac state in HVDRR patients. RECENT FINDINGS The precise spectrum of vitamin D activities can now be better evaluated by critical analysis of mouse models with targeted deletion of the gene encoding the vitamin D receptor (VDR). Of special interest is the unraveling of the role of VDR in calcium absorption and cardiac status in VDR-knockout mice. The facts that VDR-knockout mice up-regulate intestinal calcium absorption and skeletal mineralization independently of the VDR during pregnancy and lactation point to the existence of VDR-independent mechanisms that are involved in calcium absorption. The observation that mice with genetic disruption of the 1α-hydroxylase gene or of the VDR gene have an overstimulated RAS and consequently develop high blood pressure and cardiac hypertrophy raised concern about potential risks to the cardiovascular system in HVDRR patients. SUMMARY The current review summarizes the new understanding of the effects of vitamin D on calcium absorption, the RAS, and heart hypertrophy derived from studying HVDRR patients from infancy to their mid-30s.
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Affiliation(s)
- Dov Tiosano
- Pediatric Endocrinology, Meyer Children's Hospital, Rambam Healthcare Campus, Haifa, Israel.
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Abstract
CONTEXT Animal studies suggest that hypophosphatemic rickets (HPR) is associated with muscle function deficits, but it is unknown whether humans with HPR have a muscle disorder. OBJECTIVE Our objective was to assess calf muscle size and density (an indicator of muscle quality) and lower extremity muscle function in patients with HPR. SETTING The study was carried out in the outpatient department of a pediatric orthopedic hospital. PATIENTS AND OTHER PARTICIPANTS Participants included 34 individuals with HPR (6-60 yr; nine males) and 34 age- and gender-matched controls. MAIN OUTCOME MEASURES Calf muscle parameters (muscle cross-sectional area and density) were measured by peripheral quantitative computed tomography. Lower extremity muscle function (peak force per body weight and peak power per body mass) was measured by jumping mechanography through five tests with different levels of difficulty: multiple two-legged hopping, multiple one-legged hopping, single two-legged jump, chair-rise test, and heel-rise test. RESULTS Compared with age- and gender-matched controls, patients with HPR had normal muscle size (P = 0.58) but lower muscle density (P = 0.008) and lower peak muscle force and power (P < 0.001 in each test). Muscle function tests were also lower in the subgroup of patients with straight legs (n = 13) than in controls, even though patients with straight legs had higher muscle function test results than patients with severe leg deformities. CONCLUSIONS The present study suggests that muscle weakness is a clinical feature of HPR. Lower muscle quality and limb deformities contribute to this functional deficit.
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Beck-Nielsen SS. Rickets in Denmark. Dan Med J 2012; 59:B4384. [PMID: 22293055] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Rickets is a heterogeneous group of diseases of the growing child caused by defect mineralization of bone. Nutritional rickets is caused by deficiency of vitamin D, calcium or both. Several hereditary forms of rickets exist where the disease proceeds into adulthood. Nutritional rickets was common in the past, but by introduction of preventative administration of cod liver oil and vitamin D supplementation, nutritional rickets became a rarity. During the last decades, case reports of nutritional rickets reappear in the industrialized countries. It is the general conception that in the industrialized countries, hereditary rickets is the most prevalent cause of rickets today. However, the incidence of nutritional rickets and the incidence and prevalence of hereditary rickets in Scandinavia are unknown. The most common form of hereditary rickets is hypophosphatemic rickets (HR). The geno- and phenotype among Scandinavian patients have not been characterized. Especially, the disease in adult patients is not well described. Moreover, there are conflicting reports of the benefits of medical treatment throughout childhood, and in addition on gender differences in disease severity.
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Tiosano D, Hadad S, Chen Z, Nemirovsky A, Gepstein V, Militianu D, Weisman Y, Abrams SA. Calcium absorption, kinetics, bone density, and bone structure in patients with hereditary vitamin D-resistant rickets. J Clin Endocrinol Metab 2011; 96:3701-9. [PMID: 21917877 DOI: 10.1210/jc.2011-1432] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/12/2023]
Abstract
BACKGROUND Hereditary 1,25-dihydroxyvitamin D-resistant rickets (HVDRR) is caused by mutations in the vitamin D receptor gene. Children with HVDRR suffer from severe hypocalcemia and rickets that are treatable with extremely high-dose calcium supplements. Surprisingly, spontaneous recovery of calcium metabolism occurs after the end of puberty without the need for further calcium supplementation. OBJECTIVES To evaluate the role of vitamin D receptor in intestinal calcium absorption and bone, we investigated intestinal fractional calcium absorption (FCA), bone calcium accretion (Vo+), bone mineral density (BMD), and bone structure parameters in HVDRR patients from infancy into adulthood. PATIENTS AND METHODS Seventeen HVDRR patients aged 1.5-37 yr were investigated. FCA and Vo+ were determined by stable-calcium isotopes. BMD was determined by dual-energy x-ray absorptiometry and bone structure by high-resolution magnetic resonance imaging. RESULTS FCA in patients aged 1.5-17 yr was 34.9 ± 11.2% compared with 57.3 ± 2.0% in age-matched controls (P < 0.00004), whereas in patients aged 18-26 yr, it was 82.0 ± 7.8 and 53.6 ± 1.2% in controls (P < 0.001). FCA of patients older than 29 yr was comparable to controls. Patients aged 18-26 yr had higher Vo+ than controls (P < 0.02). Patients under 18 and over 29 yr of age had Vo+ comparable to controls. Femoral-neck BMD Z-score was -2.38 ± 0.3 in patients under 18 yr and 0.28 ± 0.87 in postpubertal patients (P < 0.0001). Bone structure by high-resolution magnetic resonance imaging and bone parameters of HVDRR patients and controls were similar. CONCLUSIONS Evidence from HVDRR patients reveals that calcium absorption is highly vitamin D dependent during infancy until the end of puberty, after which there is a period of about 10 yr in which mechanisms other than vitamin D-dependent ones are substantially involved in calcium absorption.
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Affiliation(s)
- Dov Tiosano
- Division of Pediatric Endocrinology, Meyer Children's Hospital, Rambam Health Care Campus, Haifa 31096, Israel.
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Carpenter TO, Imel EA, Holm IA, Jan de Beur SM, Insogna KL. A clinician's guide to X-linked hypophosphatemia. J Bone Miner Res 2011; 26:1381-8. [PMID: 21538511 PMCID: PMC3157040 DOI: 10.1002/jbmr.340] [Citation(s) in RCA: 373] [Impact Index Per Article: 28.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/31/2010] [Revised: 12/28/2010] [Accepted: 01/13/2011] [Indexed: 11/10/2022]
Abstract
X-linked hypophosphatemia (XLH) is the prototypic disorder of renal phosphate wasting, and the most common form of heritable rickets. Physicians, patients, and support groups have all expressed concerns about the dearth of information about this disease and the lack of treatment guidelines, which frequently lead to missed diagnoses or mismanagement. This perspective addresses the recommendation by conferees for the dissemination of concise and accessible treatment guidelines for clinicians arising from the Advances in Rare Bone Diseases Scientific Conference held at the NIH in October 2008. We briefly review the clinical and pathophysiologic features of the disorder and offer this guide in response to the conference recommendation, based on our collective accumulated experience in the management of this complex disorder.
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Affiliation(s)
| | - Erik A. Imel
- Indiana University School of Medicine, Indianapolis IN
| | - Ingrid A. Holm
- Division of Genetics, Program in Genomics, and the Manton Center for Orphan Disease Research, Children's Hospital Boston and Harvard Medical School, Boston, MA
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Moreira AI, Ferreira G, Santos M, Baptista A, Ferreira EO. Epidermal nevus syndrome associated with hypophosphatemic rickets. Dermatol Online J 2010; 16:14. [PMID: 20875335] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/29/2023] Open
Abstract
Epidermal Nevus Syndrome (ENS) is characterized by epidermal nevi associated with abnormalities involving the nervous, skeletal, and other systems. Rarely, hypophosphatemic rickets has been observed in association with epidermal nevi. A patient with ENS with right-sided serpiginous skin lesions, generalized weakness, and diffuse osteopenia associated with hypophosphatemic rickets is described. Medical management was enough to correct the clinical picture. The pathogenic mechanism involved in the onset of hypophosphatemic rickets in ENS is not fully clarified. Different studies suggest that phosphaturia, caused by circulating factor(s), called "phosphatonin(s)," may be secreted by an epidermal nevus. The nature of the phosphaturic factor(s) is not well understood, but elevated levels of circulating FGF-23 were recently reported in one patient with hypophosphatemic rickets. The authors suggest that serum FGF-23 measurement be included in the workup of this kind of rickets because there is growing evidence that in these situations the epidermal nevi produce a phosphaturic factor.
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37
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Kitanaka S. [Genetic basis for skeletal disease. Hereditary rickets]. Clin Calcium 2010; 20:1238-1244. [PMID: 20675935] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
Hereditary rickets is caused by inborn error of vitamin D activation, vitamin D receptor (VDR) function or increased urinary phosphate excretion. Loss-of-function mutation of 1alpha-hydroxylase gene and loss-of-function mutation of VDR gene result in vitamin D-dependent rickets type I and type II, respectively. X-linked hypophosphatemic rickets (XLH) is the most common type of hypophosphatemic rickets, and autosomal dominant (ADHR) and negative (ARHR) types are rare. The diagnosis may be sometimes difficult and increasing cases of vitamin D deficiency must be distinguished.
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Affiliation(s)
- Sachiko Kitanaka
- Department of Pediatrics, Graduate School of Medicine, The University of Tokyo
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38
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Beck-Nielsen SS, Brusgaard K, Rasmussen LM, Brixen K, Brock-Jacobsen B, Poulsen MR, Vestergaard P, Ralston SH, Albagha OME, Poulsen S, Haubek D, Gjørup H, Hintze H, Andersen MG, Heickendorff L, Hjelmborg J, Gram J. Phenotype presentation of hypophosphatemic rickets in adults. Calcif Tissue Int 2010; 87:108-19. [PMID: 20524110 DOI: 10.1007/s00223-010-9373-0] [Citation(s) in RCA: 98] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/08/2009] [Accepted: 04/25/2010] [Indexed: 02/02/2023]
Abstract
Hypophosphatemic rickets (HR) is a group of rare disorders caused by excessive renal phosphate wasting. The purpose of this cross-sectional study of 38 HR patients was to characterize the phenotype of adult HR patients. Moreover, skeletal and endodontic severity scores were defined to assess possible gender differences in disease severity in patients with genetically verified X-linked HR. Compared to normal reference data, i.e., z = 0, HR patients had significantly lower final height, with a mean difference in z-score of -1.9 (95% CI -2.4 to -1.4, P < 0.001). Compared to paired z-scores of final height, z-scores of leg length were significantly lower and those of sitting height were significantly higher (P < 0.001), resulting in disproportion as indicated by the significantly elevated sitting height ratio, mean difference in z-score of 2.6 (95% CI 2.1-3.1, P < 0.001). Z-scores of head circumference (median 1.4, range -0.4 to 5.5, P < 0.001) and z-scores of bone mineral density (BMD) of the lumbar spine (median 1.9, range -1.5 to 8.6, P < 0.001) were significantly elevated compared to normal reference data. The relative risk (RR) of fracture was reduced (RR = 0.34, 95% CI 0.20-0.57, P < 0.001). The skeletal severity score tended to be higher in males compared to females (P = 0.07), and no gender difference in endodontic severity was found. In conclusion, adult HR patients were characterized by short stature and were disproportioned. They had elevated BMD of the lumbar spine and a reduced risk of fractures. We found a tendency for males to be more severely affected than females.
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Affiliation(s)
- Signe S Beck-Nielsen
- Department of Pediatrics, H. C. Andersen Children's Hospital, Odense University Hospital, Sdr. Boulevard 29, 5000 Odense, Denmark.
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Tanaka H. [Bone and joint diseases in children. Rickets]. Clin Calcium 2010; 20:833-839. [PMID: 20513940] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
Rickets is a disorder of growth plate chondrocytes. Its basic pathophysiology has been revealed as a defect in apoptosis of hypertrophic chondrocytes induced by low phosphate concentration in the body fluid. This review summarized recent topics in two major forms of rickets, vitamin D deficient rickets and hereditary hypophosphatemic rickets. Vitamin D deficient rickets reappeared all over the world due to environmental change. The knowledge in basic pathophysiology of the hereditary hypophosphatemic rickets is increasing rapidly after the discovery of fibroblast growth factor 23 and the responsible genes have been revealed. The finding may support to uncover the whole truth of phosphate metabolism.
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Affiliation(s)
- Hiroyuki Tanaka
- Department of Pediatrics, Okayama Saiseikai General Hospital
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40
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Seitz S, Barvencik F, Gebauer M, Albers J, Schulze J, Streichert T, Amling M, Schinke T. Preproenkephalin (Penk) is expressed in differentiated osteoblasts, and its deletion in Hyp mice partially rescues their bone mineralization defect. Calcif Tissue Int 2010; 86:282-93. [PMID: 20204609 DOI: 10.1007/s00223-010-9344-5] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/26/2009] [Accepted: 02/15/2010] [Indexed: 10/19/2022]
Abstract
Although our understanding of the molecular mechanisms controlling osteoblast differentiation and function is steadily increasing, there are still many open questions, especially regarding the regulation of bone matrix mineralization. For instance, while there is hallmark evidence for the importance of the endopeptidase Phex, whose inactivation in Hyp mice or human patients causes X-linked hypophosphatemic rickets, it is still largely unknown how Phex controls bone mineralization since a physiological substrate for its endopeptidase activity has not been identified yet. Using a genome-wide expression analysis comparing primary calvarial osteoblasts, we have identified preproenkephalin (Penk) as a gene that is selectively expressed in mineralized cultures. Since a role of enkephalin in the regulation of bone remodeling has been suggested previously and since Leu-enkephalin is known to be cleaved by Phex, we analyzed whether Penk expression in osteoblasts is physiologically relevant. Through skeletal analysis of a Penk-deficient mouse model, we found that Penk expression is dispensable for bone development and remodeling since we could not detect any defect following nondecalcified bone histology and histomorphometry compared to wild-type littermates. When Penk was deleted in Phex-deficient Hyp mice, however, we observed a significant reduction of the osteoid enrichment at 24 weeks of age, whereas their disturbance of mineral homeostasis was not affected by the additional absence of the Penk gene. Taken together, our data provide the first in vivo analysis concerning the role of Penk in osteoblasts.
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Affiliation(s)
- S Seitz
- Department of Osteology and Biomechanics, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
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Clausmeyer S, Hesse V, Clemens PC, Engelbach M, Kreuzer M, Becker-Rose P, Spital H, Schulze E, Raue F. Mutational analysis of the PHEX gene: novel point mutations and detection of large deletions by MLPA in patients with X-linked hypophosphatemic rickets. Calcif Tissue Int 2009; 85:211-20. [PMID: 19513579 DOI: 10.1007/s00223-009-9260-8] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/27/2008] [Accepted: 04/30/2009] [Indexed: 12/22/2022]
Abstract
X-Linked hypophosphatemic rickets (HYP, XLH) is a disorder of phosphate homeostasis, characterized by renal phosphate wasting and hypophosphatemia, with normal to low 1,25-dihydroxy vitamin D3 serum levels. The purpose of our study was the detection of inactivating mutations in the PHEX gene, the key enzyme in the pathogenesis of XLH. The 16 patients, representing eight families, presented with suspected XLH from biochemical and clinical evidence. All 16 were referred for mutational analysis of the PHEX gene. We detected three novel disease-causing mutations, C59S, Q394X, and W602, for which a loss of function can be predicted. A G28S variation, found in two healthy probands, may be a rare polymorphism. Another mutation, A363 V, is localized on the same allele as the C59S mutation, thus its functional consequences cannot be proven. Furthermore, we detected a deletion of three nucleotides in exon 15 which resulted in the loss of amino acid threonine 535. Heterozygosity of this mutation in a male patient without any chromosomal aberrations suggests its presence as a mosaic. Novel large deletions were detected using multiplex ligation-dependent probe amplification (MLPA) analysis. Two of these deletions, loss of exon 22 alone or exons 21 and 22 together, may result in the translation of a C-terminal truncated protein. Two large deletions comprise exons 1-9 and exons 4-20, respectively, and presumably result in a nonfunctional protein. We conclude that molecular genetic analysis confirms the clinical diagnosis of XLH and should include sequence analysis as well as the search for large deletions, which is facilitated by MLPA.
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Affiliation(s)
- S Clausmeyer
- Endocrine Practice Prof. Raue, Heidelberg, Germany.
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42
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Liang G, Katz LD, Insogna KL, Carpenter TO, Macica CM. Survey of the enthesopathy of X-linked hypophosphatemia and its characterization in Hyp mice. Calcif Tissue Int 2009; 85:235-46. [PMID: 19609735 PMCID: PMC2988401 DOI: 10.1007/s00223-009-9270-6] [Citation(s) in RCA: 84] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/13/2009] [Accepted: 06/09/2009] [Indexed: 12/22/2022]
Abstract
X-linked hypophosphatemia (XLH) is characterized by rickets and osteomalacia as a result of an inactivating mutation of the PHEX (phosphate-regulating gene with homology to endopeptidases on the X chromosome) gene. PHEX encodes an endopeptidase that, when inactivated, results in elevated circulating levels of FGF-23, a novel phosphate-regulating hormone (a phosphatonin), thereby resulting in increased phosphate excretion and impaired bone mineralization. A generalized and severe mineralizing enthesopathy in patients with XLH was first reported in 1985; we likewise report a survey in which we found evidence of enthesopathy in fibrocartilaginous insertion sites, as well as osteophyte formation, in the majority of patients. Nonetheless, there has been very little focus on the progression and pathogenesis underlying the paradoxical heterotopic calcification of tendon and ligament insertion sites. Such studies have been hampered by lack of a model of mineralizing enthesopathy. We therefore characterized the involvement of the most frequently targeted fibrocartilaginous tendon insertion sites in Hyp mice, a murine model of the XLH mutation that phenocopies the human syndrome in every detail including hypophosphatemia and elevated FGF-23. Histological examination of the affected entheses revealed that mineralizing insertion sites, while thought to involve bone spur formation, were not due to bone-forming osteoblasts but instead to a significant expansion of mineralizing fibrocartilage. Our finding that enthesis fibrocartilage cells specifically express fibroblast growth factor receptor 3 (FGFR3)/Klotho suggests that the high circulating levels of FGF-23, characteristic of XLH and Hyp mice, may be part of the biochemical milieu that underlies the expansion of mineralizing enthesis fibrocartilage.
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Affiliation(s)
- Guoying Liang
- Department of Internal Medicine/Endocrinology, Yale University, P.O. Box 208020, New Haven, CT 06520-8020, USA
| | - Lee D. Katz
- Department of Diagnostic Radiology, Yale University, New Haven, CT, USA
| | - Karl L. Insogna
- Department of Internal Medicine/Endocrinology, Yale University, P.O. Box 208020, New Haven, CT 06520-8020, USA
| | | | - Carolyn M. Macica
- Department of Internal Medicine/Endocrinology, Yale University, P.O. Box 208020, New Haven, CT 06520-8020, USA
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Yasuda T. [Rickets]. Clin Calcium 2009; 19:109-116. [PMID: 19122271] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
This review mainly describes on childhood vitamin D deficiency and x-linked hypophosphatemic rickets. Though nutritional state has improved dramatically, 25 (OH) D level, which is a good indicator of vitamin D status, is marginal especially in winter, and vitamin D deficiency is not rare in Japan. The PTH/Vitamin D axis does not account for the entire picture of x-linked hypophosphatemic rickets, and a new bone (osteocyte) -renal metabolic milieu has emerged and loss of PHEX, mostly expressed in osteocytes, is proposed to result in inappropriate processing of MEPE and consequent reduction in bone mineralization and an increase in circulating FGF23 to give rise to phosphaturia and hypophosphatemia.
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Abstract
Fibroblast growth factor (FGF) 23 has been identified as the last member of FGF family. FGF23 reduces serum phosphate level by suppressing proximal tubular phosphate reabsorption and intestinal phosphate absorption. FGF23 is produced by bone and acts on the kidney through a specific receptor system which is composed of Klotho and certain subtypes of FGF receptors. Excess actions of FGF23 cause several hypophosphatemic diseases characterized by impaired renal phosphate reabsorption and rickets/osteomalacia. In contrast, deficient actions of FGF23 result in hyperphosphatemic tumoral calcinosis with enhanced renal phosphate reabsorption. These results indicate that FGF23 works as a hormone to regulate the serum phosphate level.
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Affiliation(s)
- Seiji Fukumoto
- Division of Nephrology and Endocrinology, Department of Internal Medicine, University of Tokyo Hospital.
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45
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Farrow EG, Davis SI, Ward LM, White KE. The role of DMP1 in autosomal recessive hypophosphatemic rickets. J Musculoskelet Neuronal Interact 2007; 7:310-312. [PMID: 18094488] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Grants] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Affiliation(s)
- E G Farrow
- Department of Medical and Molecular Genetics, Indiana University School of Medicine, Indianapolis, IN 46202, USA
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46
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Harris SE, Gluhak-Heinrich J, Harris MA, Yang W, Bonewald LF, Riha D, Rowe PSN, Robling AG, Turner CH, Feng JQ, McKee MD, Nicollela D. DMP1 and MEPE expression are elevated in osteocytes after mechanical loading in vivo: theoretical role in controlling mineral quality in the perilacunar matrix. J Musculoskelet Neuronal Interact 2007; 7:313-315. [PMID: 18094489 PMCID: PMC3357082] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Key Words] [MESH Headings] [Grants] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Affiliation(s)
- S E Harris
- University of Texas Health Science Center at San Antonio, TX 78229, USA.
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47
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Abstract
The hypophosphatemic conditions that interfere in bone mineralization comprise many hereditary or acquired diseases, all of them sharing the same pathophysiologic mechanism: reduction in the phosphate reabsorption by the renal tubuli. This process leads to chronic hyperphosphaturia and hypophosphatemia, associated with inappropriately normal or low levels of calcitriol, causing osteomalacia or rickets in children and osteomalacia in adults. X-linked hypophosphatemic rickets, autosomal-dominant hypophosphatemic rickets, and tumor-induced osteomalacia are the main syndromes involved in the hypophosphatemic rickets. Although these conditions exhibit different etiologies, there is a common link among them: increased activity of a phosphaturic factor, being the fibroblast growth factor 23 (FGF-23) the most studied one and to which is attributed a central role in the pathophysiology of the hyperphosphaturic disturbances. Activating mutations of FGF-23 and inactivating mutations in the PHEX gene (a gene on the X chromosome that codes for a Zn-metaloendopeptidase proteolytic enzyme which regulates the phosphate) involved in the regulation of FGF-23 have been identified and have been implicated in the pathogenesis of these disturbances. Genetic studies tend to show that the phosphorus homeostasis depends on a complex osteo-renal metabolic axis, whose mechanisms of interaction have been poorly understood so far. This paper reviews the current knowledge status concerning the pathophysiology of phosphate metabolism regulation and the pathophysiologic basis of hypophosphatemic rickets. It also analyzes the clinical picture and the therapeutic aspects of these conditions as well.
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Affiliation(s)
- Hamilton de Menezes Filho
- Instituto da Criança, Hospital das Clínicas, Medical School, São Paulo University, São Paulo, SP, Brazil
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48
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Michigami T. [X-linked hypophosphatemic rickets]. Nihon Naika Gakkai Zasshi 2007; 96:725-30. [PMID: 17506311 DOI: 10.2169/naika.96.725] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
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49
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Abstract
Inorganic phosphate (Pi) is fundamental to cellular metabolism and skeletal mineralization. Ingested Pi is absorbed by the small intestine, deposited in bone, and filtered by the kidney where it is reabsorbed and excreted in amounts determined by the specific needs of the organism. Two distinct renal Na-dependent Pi transporters, type IIa (NPT2a, SLC34A1) and type IIc (NPT2c, SLC34A3), are expressed in brush border membrane of proximal tubular cells where the bulk of filtered Pi is reabsorbed. Both are regulated by dietary Pi intake and parathyroid hormone. Regulation is achieved by changes in transporter protein abundance in the brush border membrane and requires the interaction of the transporter with scaffolding and signaling proteins. The demonstration of hypophosphatemia secondary to decreased renal Pi reabsorption in mice homozygous for the disrupted type IIa gene underscores its crucial role in the maintenance of Pi homeostasis. Moreover, the recent identification of mutations in the type IIc gene in patients with hereditary hypophosphatemic rickets with hypercalciuria attests to the importance of this transporter in Pi conservation and subsequent skeletal mineralization. Two novel Pi regulating genes, PHEX and FGF23, play a role in the pathophysiology of inherited and acquired hypophosphatemic skeletal disorders and studies are underway to define their mechanism of action on renal Pi handling in health and disease.
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50
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Abstract
The objective of these investigations was to determine if the receptor-dependent effects of 1,25-dihydroxyvitamin D were essential for normal skeletal growth. Mice with targeted ablation of the vitamin D receptor were engineered, and the skeletal consequences of vitamin D receptor ablation were studied in the presence of normal and abnormal mineral ion homeostasis. Prevention of abnormal mineral ion homeostasis resulted in the development of a normal skeleton in the absence of a functional vitamin D receptor. The metabolic cause of rickets was found to be hypophosphatemia. The major receptor-dependent actions of 1,25-dihydroxyvitamin D on skeletal development are indirect and are a reflection of the role of this hormone on intestinal calcium absorption.
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Affiliation(s)
- Marie B Demay
- Endocrine Unit, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts, USA.
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