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Baroncelli GI, Comberiati P, Aversa T, Baronio F, Cassio A, Chiarito M, Cosci o di Coscio M, De Sanctis L, Di Iorgi N, Faienza MF, Fintini D, Franceschi R, Kalapurackal M, Longhi S, Mariani M, Pitea M, Secco A, Tessaris D, Vierucci F, Wasniewska M, Weber G, Mora S. Diagnosis, treatment, and management of rickets: a position statement from the Bone and Mineral Metabolism Group of the Italian Society of Pediatric Endocrinology and Diabetology. Front Endocrinol (Lausanne) 2024; 15:1383681. [PMID: 38706696 PMCID: PMC11066174 DOI: 10.3389/fendo.2024.1383681] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/07/2024] [Accepted: 04/03/2024] [Indexed: 05/07/2024] Open
Abstract
Rickets results from impaired mineralization of growing bone due to alterations in calcium and phosphate homeostasis. Clinical signs of rickets are related to the age of the patient, the duration of the disease, and the underlying disorder. The most common signs of rickets are swelling of the wrists, knees or ankles, bowing of the legs (knock-knees, outward bowing, or both) and inability to walk. However, clinical features alone cannot differentiate between the various forms of rickets. Rickets includes a heterogeneous group of acquired and inherited diseases. Nutritional rickets is due to a deficiency of vitamin D, dietary calcium or phosphate. Mutations in genes responsible for vitamin D metabolism or function, the production or breakdown of fibroblast growth factor 23, renal phosphate regulation, or bone mineralization can lead to the hereditary form of rickets. This position paper reviews the relevant literature and presents the expertise of the Bone and Mineral Metabolism Group of the Italian Society of Pediatric Endocrinology and Diabetology (SIEDP). The aim of this document is to provide practical guidance to specialists and healthcare professionals on the main criteria for diagnosis, treatment, and management of patients with rickets. The various forms of rickets are discussed, and detailed references for the discussion of each form are provided. Algorithms to guide the diagnostic approach and recommendations to manage patients with rare forms of hereditary rickets are proposed.
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Affiliation(s)
- Giampiero I. Baroncelli
- Pediatric and Adolescent Endocrinology, Division of Pediatrics, Department of Obstetrics, Gynecology and Pediatrics, University Hospital, Pisa, Italy
| | - Pasquale Comberiati
- Pediatric and Adolescent Endocrinology, Division of Pediatrics, Department of Obstetrics, Gynecology and Pediatrics, University Hospital, Pisa, Italy
- Department of Clinical and Experimental Medicine, Section of Paediatrics, University of Pisa, Pisa, Italy
| | - Tommaso Aversa
- Department of Human Pathology of Adulthood and Childhood, University of Messina, Messina, Italy
- Pediatric Unit, University Hospital “G. Martino”, Messina, Italy
| | - Federico Baronio
- Pediatric Unit, IRCCS Azienda Ospedaliero-Universitaria di Bologna, Bologna, Italy
| | - Alessandra Cassio
- Pediatric Unit, IRCCS Azienda Ospedaliero-Universitaria di Bologna, Bologna, Italy
- Department of Medical and Surgical Sciences, University of Bologna, Bologna, Italy
| | - Mariangela Chiarito
- Pediatric Unit, Department of Precision and Regenerative Medicine and Ionian Area, University “A. Moro” of Bari, Bari, Italy
| | - Mirna Cosci o di Coscio
- Pediatric and Adolescent Endocrinology, Division of Pediatrics, Department of Obstetrics, Gynecology and Pediatrics, University Hospital, Pisa, Italy
| | - Luisa De Sanctis
- Division of Pediatric Endocrinology, Department of Public Health and Pediatrics, University of Turin, Regina Margherita Children’s Hospital, Turin, Italy
| | - Natascia Di Iorgi
- Department of Pediatrics, IRCCS Istituto Giannina Gaslini, Genova, Italy
- Department of Neuroscience, Rehabilitation, Ophthalmology, Genetics, Maternal and Child Health, University of Genova, Genova, Italy
| | - Maria Felicia Faienza
- Pediatric Unit, Department of Precision and Regenerative Medicine and Ionian Area, University “A. Moro” of Bari, Bari, Italy
| | - Danilo Fintini
- Endocrinology and Diabetology Unit, Bambino Gesù Children Hospital, IRCCS, Rome, Italy
| | - Roberto Franceschi
- Department of Pediatrics, Santa Chiara Hospital of Trento, APSS, Trento, Italy
| | - Mila Kalapurackal
- Department of Pediatrics, Hospital of Bolzano (SABES-ASDAA), Teaching Hospital of Paracelsus Medical University (PMU), Bolzano, Italy
| | - Silvia Longhi
- Department of Pediatrics, Hospital of Bolzano (SABES-ASDAA), Teaching Hospital of Paracelsus Medical University (PMU), Bolzano, Italy
| | - Michela Mariani
- Endocrinology and Diabetology Unit, Bambino Gesù Children Hospital, IRCCS, Rome, Italy
| | - Marco Pitea
- Pediatric Endocrinology Unit, Department of Pediatrics, IRCCS Ospedale San Raffaele, Milan, Italy
| | - Andrea Secco
- Pediatric and Pediatric Emergency Unit, Children Hospital, Azienda Ospedaliera SS Antonio e Biagio e C. Arrigo, Alessandria, Italy
| | - Daniele Tessaris
- Division of Pediatric Endocrinology, Department of Public Health and Pediatrics, University of Turin, Regina Margherita Children’s Hospital, Turin, Italy
| | | | - Malgorzata Wasniewska
- Department of Human Pathology of Adulthood and Childhood, University of Messina, Messina, Italy
| | - Giovanna Weber
- Pediatric Endocrinology Unit, Department of Pediatrics, IRCCS Ospedale San Raffaele, Milan, Italy
| | - Stefano Mora
- Laboratory of Pediatric Endocrinology, Department of Pediatrics, IRCCS Ospedale San Raffaele, Milan, Italy
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Perumal NL, Padidela R. Phosphate Homeostasis and Disorders of Phosphate Metabolism. Curr Pediatr Rev 2024; 20:412-425. [PMID: 36545737 DOI: 10.2174/1573396319666221221121350] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/23/2022] [Revised: 11/25/2022] [Accepted: 11/28/2022] [Indexed: 12/24/2022]
Abstract
Phosphate is indispensable for human life and evolutionary changes over several millions of years have established tightly regulated mechanisms to ensure phosphate homeostasis. In this process, calcium and phosphate metabolism have come to be intricately linked together. Three hormones (PTH, FGF23 and Calcitriol) maintain the fine balance of calcium and phosphate metabolism through their actions at three sites (the gut, the kidneys and the skeleton). Disorders that disrupt this balance can have serious clinical consequences. Acute changes in serum phosphate levels can result in life threatening complications like respiratory failure and cardiac arrythmias. Chronic hypophosphataemia predominantly affects the musculoskeletal system and presents as impaired linear growth, rickets, osteomalacia and dental problems. Hyperphosphataemia is very common in the setting of chronic kidney disease and can be difficult to manage. A thorough understanding of calcium and phosphate homeostasis is essential to diagnose and treat conditions associated with hypo and hyperphosphataemia. In this review, we will discuss the calcium and phosphate metabolism, aetiologies and management of hypo and hyperphosphataemia.
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Affiliation(s)
| | - Raja Padidela
- Department of Endocrinology, Royal Manchester Children's Hospital, Manchester, United Kingdom
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AlSubaihin A, Harrington J. Hereditary Rickets: A Quick Guide for the Pediatrician. Curr Pediatr Rev 2024; 20:380-394. [PMID: 36475338 DOI: 10.2174/1573396319666221205123402] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/12/2022] [Revised: 09/10/2022] [Accepted: 11/01/2022] [Indexed: 12/12/2022]
Abstract
With the increased discovery of genes implicated in vitamin D metabolism and the regulation of calcium and phosphate homeostasis, a growing number of genetic forms of rickets are now recognized. These are categorized into calciopenic and phosphopenic rickets. Calciopenic forms of hereditary rickets are caused by genetic mutations that alter the enzymatic activity in the vitamin D activation pathway or impair the vitamin D receptor action. Hereditary forms of phosphopenic rickets, on the other hand, are caused by genetic mutations that lead to increased expression of FGF23 hormone or that impair the absorptive capacity of phosphate at the proximal renal tubule. Due to the clinical overlap between acquired and genetic forms of rickets, identifying children with hereditary rickets can be challenging. A clear understanding of the molecular basis of hereditary forms of rickets and their associated biochemical patterns allow the health care provider to assign the correct diagnosis, avoid non-effective interventions and shorten the duration of the diagnostic journey in these children. In this mini-review, known forms of hereditary rickets listed on the Online Mendelian Inheritance in Man database are discussed. Further, a clinical approach to identify and diagnose children with hereditary forms of rickets is suggested.
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Affiliation(s)
- Abdulmajeed AlSubaihin
- Department of Pediatrics, College of Medicine, King Saud University, Riyadh, Saudi Arabia
- King Saud University Medical City, Riyadh, Saudi Arabia
| | - Jennifer Harrington
- Division of Endocrinology, Women's and Children's Health Network, North Adelaide, Australia
- Faculty of Health and Medical Sciences, University of Adelaide, Adelaide, Australia
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Liu P, Li J, Tang L, Cong W, Jin H, Zhang H, Cui B, Yang S, Xiao J, Liu C, Saiyin W. Mutations of family with sequence similarity 20-member C gene causing lethal and nonlethal Raine syndrome causes hypophosphatemia rickets. J Cell Physiol 2023; 238:2556-2569. [PMID: 37698039 DOI: 10.1002/jcp.31105] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2023] [Revised: 08/01/2023] [Accepted: 08/07/2023] [Indexed: 09/13/2023]
Abstract
Family with sequence similarity 20-member C (FAM20C) is a kinase specific to most of the secreted phosphoproteome. FAM20C has been identified as the causative gene of Raine syndrome, initially characterized by lethal osteosclerosis bone dysplasia. However, since the identification of the cases of nonlethal Raine syndrome characterized by hypophosphatemia rickets, the previous definition of Raine syndrome has become debatable and raised a question about the role of mutations of FAM20C in controversial skeletal manifestation in the two forms of the disease. In this study, we aimed to investigate the influence of FAM20C mutations on skeletogenesis. We developed transgenic mice expressing Fam20c mutations mimicking those associated with human lethal and nonlethal Raine syndrome. The results revealed that transgenic mice expressing the mutant Fam20c found in the lethal (KO;G374R) and nonlethal (KO;D446N) Raine syndrome exhibited osteomalacia without osteosclerotic features. Additionally, both mutants significantly increased the expression of the Fgf23, indicating that Fam20c deficiency in skeletal compartments causes hypophosphatemia rickets. Furthermore, as FAM20C kinase activity catalyzes the phosphorylation of secreted proteomes other than those in the skeletal system, global FAM20C deficiency may trigger alterations in other systems resulting in osteosclerosis secondary to hypophosphatemia rickets. Together, the findings of this study suggest that FAM20C deficiency primarily causes hypophosphatemia rickets or osteomalacia; however, the heterogeneous skeletal manifestation in Raine syndrome was not determined solely by specific mutations of FAM20C. The findings also implicated that rickets or osteomalacia caused by FAM20C deficiency would deteriorate into osteosclerosis by the defects from other systems or environmental impacts.
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Affiliation(s)
- Peihong Liu
- Department of Stomatology, The First Affiliated Hospital of Harbin Medical University, Harbin, China
- Laboratory of Longjiang Scholar, The First Affifiliated Hospital of Harbin Medical University, Harbin, China
| | - Jiaxuan Li
- Department of Stomatology, The First Affiliated Hospital of Harbin Medical University, Harbin, China
| | - Linghao Tang
- Department of Otorhinolaryngology, The First Affiliated Hospital of Dalian Medical University, Dalian, China
| | - Wei Cong
- Department of Oral Pathology, School of Stomatology, Dalian Medical University, Dalian, China
| | - Han Jin
- Heilongjiang Provincial Key Laboratory of Hard Tissue Development and Regeneration, The Second Affiliated Hospital of Harbin Medical University, Harbin, China
| | - Hong Zhang
- Department of Stomatology, The First Affiliated Hospital of Harbin Medical University, Harbin, China
| | - Bing Cui
- Department of Stomatology, The First Affiliated Hospital of Harbin Medical University, Harbin, China
| | - Shan Yang
- Department of Stomatology, The First Affiliated Hospital of Harbin Medical University, Harbin, China
| | - Jing Xiao
- Department of Oral Pathology, School of Stomatology, Dalian Medical University, Dalian, China
| | - Chao Liu
- Department of Oral Pathology, School of Stomatology, Dalian Medical University, Dalian, China
| | - Wuliji Saiyin
- Department of Stomatology, The First Affiliated Hospital of Harbin Medical University, Harbin, China
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Zhang H, Xiang G, Li J, He S, Wang Y, Deng A, Wang Y, Guo C. Promotion effect of FGF23 on osteopenia in congenital scoliosis through FGFr3/TNAP/OPN pathway. Chin Med J (Engl) 2023; 136:1468-1477. [PMID: 37192015 PMCID: PMC10278695 DOI: 10.1097/cm9.0000000000002690] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2022] [Indexed: 05/18/2023] Open
Abstract
BACKGROUND Congenital scoliosis (CS) is a complex spinal malformation of unknown etiology with abnormal bone metabolism. Fibroblast growth factor 23 (FGF23), secreted by osteoblasts and osteocytes, can inhibit bone formation and mineralization. This research aims to investigate the relationship between CS and FGF23. METHODS We collected peripheral blood from two pairs of identical twins for methylation sequencing of the target region. FGF23 mRNA levels in the peripheral blood of CS patients and age-matched controls were measured. Receiver operator characteristic (ROC) curve analyses were conducted to evaluate the specificity and sensitivity of FGF23. The expression levels of FGF23 and its downstream factors fibroblast growth factor receptor 3 (FGFr3)/tissue non-specific alkaline phosphatase (TNAP)/osteopontin (OPN) in primary osteoblasts from CS patients (CS-Ob) and controls (CT-Ob) were detected. In addition, the osteogenic abilities of FGF23-knockdown or FGF23-overexpressing Ob were examined. RESULTS DNA methylation of the FGF23 gene in CS patients was decreased compared to that of their identical twins, accompanied by increased mRNA levels. CS patients had increased peripheral blood FGF23 mRNA levels and decreased computed tomography (CT) values compared with controls. The FGF23 mRNA levels were negatively correlated with the CT value of the spine, and ROCs of FGF23 mRNA levels showed high sensitivity and specificity for CS. Additionally, significantly increased levels of FGF23, FGFr3, OPN, impaired osteogenic mineralization and lower TNAP levels were observed in CS-Ob. Moreover, FGF23 overexpression in CT-Ob increased FGFr3 and OPN levels and decreased TNAP levels, while FGF23 knockdown induced downregulation of FGFr3 and OPN but upregulation of TNAP in CS-Ob. Mineralization of CS-Ob was rescued after FGF23 knockdown. CONCLUSIONS Our results suggested increased peripheral blood FGF23 levels, decreased bone mineral density in CS patients, and a good predictive ability of CS by peripheral blood FGF23 levels. FGF23 may contribute to osteopenia in CS patients through FGFr3/TNAP / OPN pathway.
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Affiliation(s)
- Hongqi Zhang
- Department of Spine Surgery and Orthopaedics, Xiangya Hospital, Central South University, Changsha, Hunan 410000, China
- National Clinical Research Center for Geriatric Disorder, Xiangya Hospital, Central South University, Changsha, Hunan 410000, China
| | - Gang Xiang
- Department of Spine Surgery and Orthopaedics, Xiangya Hospital, Central South University, Changsha, Hunan 410000, China
- National Clinical Research Center for Geriatric Disorder, Xiangya Hospital, Central South University, Changsha, Hunan 410000, China
| | - Jiong Li
- Department of Spine Surgery and Orthopaedics, Xiangya Hospital, Central South University, Changsha, Hunan 410000, China
- National Clinical Research Center for Geriatric Disorder, Xiangya Hospital, Central South University, Changsha, Hunan 410000, China
| | - Sihan He
- Department of Spine Surgery and Orthopaedics, Xiangya Hospital, Central South University, Changsha, Hunan 410000, China
- National Clinical Research Center for Geriatric Disorder, Xiangya Hospital, Central South University, Changsha, Hunan 410000, China
| | - Yunjia Wang
- Department of Spine Surgery and Orthopaedics, Xiangya Hospital, Central South University, Changsha, Hunan 410000, China
- National Clinical Research Center for Geriatric Disorder, Xiangya Hospital, Central South University, Changsha, Hunan 410000, China
| | - Ang Deng
- Department of Spine Surgery and Orthopaedics, Xiangya Hospital, Central South University, Changsha, Hunan 410000, China
- National Clinical Research Center for Geriatric Disorder, Xiangya Hospital, Central South University, Changsha, Hunan 410000, China
| | - Yuxiang Wang
- Department of Spine Surgery and Orthopaedics, Xiangya Hospital, Central South University, Changsha, Hunan 410000, China
- National Clinical Research Center for Geriatric Disorder, Xiangya Hospital, Central South University, Changsha, Hunan 410000, China
| | - Chaofeng Guo
- Department of Spine Surgery and Orthopaedics, Xiangya Hospital, Central South University, Changsha, Hunan 410000, China
- National Clinical Research Center for Geriatric Disorder, Xiangya Hospital, Central South University, Changsha, Hunan 410000, China
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Palma-Lara I, García Alonso-Themann P, Pérez-Durán J, Godínez-Aguilar R, Bonilla-Delgado J, Gómez-Archila D, Espinosa-García AM, Nolasco-Quiroga M, Victoria-Acosta G, López-Ornelas A, Serrano-Bello JC, Olguín-García MG, Palacios-Reyes C. Potential Role of Protein Kinase FAM20C on the Brain in Raine Syndrome, an In Silico Analysis. Int J Mol Sci 2023; 24:ijms24108904. [PMID: 37240249 DOI: 10.3390/ijms24108904] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2023] [Revised: 05/04/2023] [Accepted: 05/05/2023] [Indexed: 05/28/2023] Open
Abstract
FAM20C (family with sequence similarity 20, member C) is a serine/threonine-specific protein kinase that is ubiquitously expressed and mainly associated with biomineralization and phosphatemia regulation. It is mostly known due to pathogenic variants causing its deficiency, which results in Raine syndrome (RNS), a sclerosing bone dysplasia with hypophosphatemia. The phenotype is recognized by the skeletal features, which are related to hypophosphorylation of different FAM20C bone-target proteins. However, FAM20C has many targets, including brain proteins and the cerebrospinal fluid phosphoproteome. Individuals with RNS can have developmental delay, intellectual disability, seizures, and structural brain defects, but little is known about FAM20C brain-target-protein dysregulation or about a potential pathogenesis associated with neurologic features. In order to identify the potential FAM20C actions on the brain, an in silico analysis was conducted. Structural and functional defects reported in RNS were described; FAM20C targets and interactors were identified, including their brain expression. Gene ontology of molecular processes, function, and components was completed for these targets, as well as for potential involved signaling pathways and diseases. The BioGRID and Human Protein Atlas databases, the Gorilla tool, and the PANTHER and DisGeNET databases were used. Results show that genes with high expression in the brain are involved in cholesterol and lipoprotein processes, plus axo-dendritic transport and the neuron part. These results could highlight some proteins involved in the neurologic pathogenesis of RNS.
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Affiliation(s)
- Icela Palma-Lara
- Laboratorio de Morfología Celular y Molecular, Escuela Superior de Medicina, Instituto Politécnico Nacional, Ciudad de México 11340, Mexico
| | | | - Javier Pérez-Durán
- Instituto Nacional de Perinatología Isidro Espinosa de los Reyes, Ciudad de México 11000, Mexico
| | | | - José Bonilla-Delgado
- Unidad de Investigación, Hospital Regional de Ixtapaluca, Ixtapaluca 56530, Mexico
- Departamento de Biotecnología, Escuela de Ingeniería y Ciencias, Instituto Tecnológico de Monterrey, Toluca de Lerdo 50110, Mexico
| | - Damián Gómez-Archila
- Departamento de Oncología Quirúrgica, Hospital de Gineco-Obstetricia 3, Centro Médico Nacional "La Raza", Ciudad de México 02990, Mexico
| | | | - Manuel Nolasco-Quiroga
- Coordinación de Enseñanza e Investigación, Clínica Hospital Instituto de Seguridad y Servicios Sociales de los Trabajadores del Estado, Huauchinango 73177, Mexico
| | | | - Adolfo López-Ornelas
- División de Investigación, Hospital Juárez de México, Ciudad de México 11340, Mexico
| | - Juan Carlos Serrano-Bello
- Departamento de Patología Clínica y Experimental, Hospital Infantil de México Federico Gómez, Ciudad de México 06720, Mexico
| | | | - Carmen Palacios-Reyes
- División de Investigación, Hospital Juárez de México, Ciudad de México 11340, Mexico
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Zhang H, Lu Y, Kramer PR, Benson MD, Cheng YSL, Qin C. Intracranial calcification in Fam20c-deficient mice recapitulates human Raine syndrome. Neurosci Lett 2023; 802:137176. [PMID: 36914045 DOI: 10.1016/j.neulet.2023.137176] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2022] [Revised: 02/26/2023] [Accepted: 03/08/2023] [Indexed: 03/15/2023]
Abstract
FAM20C (family with sequence similarity 20-member C) is a protein kinase that phosphorylates secretory proteins, including the proteins that are essential to the formation and mineralization of calcified tissues. FAM20C loss-of-function mutations cause Raine syndrome in humans, characterized by generalized osteosclerosis, distinctive craniofacial dysmorphism, along with extensive intracranial calcification. Our previous studies revealed that inactivation of Fam20c in mice led to hypophosphatemic rickets. In this study, we examined the expression of Fam20c in the mouse brain and investigated brain calcification in Fam20c-deficient mice. Reverse transcription polymerase chain reaction (RT-PCR), Western-blotting and in situ hybridization analyses demonstrated the broad expression of Fam20c in the mouse brain tissue. X-ray and histological analyses showed that the global deletion of Fam20c (mediated by Sox2-cre) resulted in brain calcification in mice after postnatal 3 months and that the calcifications were bilaterally distributed within the brain. There was mild perifocal microgliosis as well as astrogliosis around calcospherites. The calcifications were first observed in the thalamus, and later in the forebrain and hindbrain. Furthermore, brain-specific deletion (mediated by Nestin-cre) of Fam20c in mice also led to cerebral calcification at an older age (postnatal 6 months), but no obvious skeletal or dental defects. Our results suggest that the local loss of FAM20C function in the brain may directly account for intracranial calcification. We propose that FAM20C plays an essential role in maintaining normal brain homeostasis and preventing ectopic brain calcification.
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Affiliation(s)
- Hua Zhang
- Department of Biomedical Sciences, Texas A&M University School of Dentistry, Dallas, TX 75246, USA.
| | - Yongbo Lu
- Department of Biomedical Sciences, Texas A&M University School of Dentistry, Dallas, TX 75246, USA
| | - Phillip R Kramer
- Department of Biomedical Sciences, Texas A&M University School of Dentistry, Dallas, TX 75246, USA
| | - M Douglas Benson
- Department of Biomedical Sciences, Texas A&M University School of Dentistry, Dallas, TX 75246, USA
| | - Yi-Shing L Cheng
- Department of Biomedical Sciences, Texas A&M University School of Dentistry, Dallas, TX 75246, USA
| | - Chunlin Qin
- Department of Biomedical Sciences, Texas A&M University School of Dentistry, Dallas, TX 75246, USA
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Dental manifestations and treatment of hypophosphatemic rickets: A case report and review of literature. BDJ Open 2023; 9:2. [PMID: 36717535 PMCID: PMC9886973 DOI: 10.1038/s41405-023-00129-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2022] [Revised: 12/29/2022] [Accepted: 01/02/2023] [Indexed: 01/31/2023] Open
Abstract
BACKGROUND The treatment and management of patients suffering from hypophosphatemic rickets (HR) remain a major challenge for dental practitioners and affected patients. OBJECTIVES To report a case of HR presenting with specific dental findings and to review the dental manifestations and treatment of HR patients. METHODS Case: A 32-year-old male presented with multiple dental abscesses and short stature. A thorough history was taken followed by clinical oral examination, and relevant radiological investigation was done. Literature research: In 2020, electronic literature searches were carried out in PubMed and complemented by a careful assessment of the reference lists of the identified relevant papers. Articles and reports fulfilled the inclusion criteria: indexed reviews, case series and case reports in English and restricted to human studies were considered. RESULTS The intraoral examination revealed multiple dental abscesses and general periodontal disease; the radiographic examination showed poorly defined lamina dura, large pulp chambers and periapical lesions. Based on the contents of the 43 articles identified in the search, the current knowledge of dental manifestations, treatment and management of HR was summarized. CONCLUSIONS As HR is a multisystem disease, multidisciplinary care is needed. By summarizing current evidences, we proposed an evidence-based dental management and provided recommendations on diagnosis and treatment of the disease. It is of profound clinical significance to acquire knowledge of the dental manifestations and provide optimal treatment options for patients.
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Hanai A, Kawabata A, Nakajima K, Masuda K, Urakawa I, Abe M, Yamazaki Y, Fukumoto S. Single-cell RNA sequencing identifies Fgf23-expressing osteocytes in response to 1,25-dihydroxyvitamin D 3 treatment. Front Physiol 2023; 14:1102751. [PMID: 36776964 PMCID: PMC9911654 DOI: 10.3389/fphys.2023.1102751] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2022] [Accepted: 01/16/2023] [Indexed: 01/28/2023] Open
Abstract
Fibroblast growth factor 23 (FGF23), a hormone, mainly produced by osteocytes, regulates phosphate and vitamin D metabolism. By contrast, 1,25-dihydroxyvitamin D3, the active form of vitamin D, has been shown to enhance FGF23 production. While it is likely that osteocytes are heterogenous in terms of gene expression profiles, specific subpopulations of Fgf23-expressing osteocytes have not been identified. Single-cell RNA sequencing (scRNA-seq) technology can characterize the transcriptome of an individual cell. Recently, scRNA-seq has been used for bone tissue analysis. However, owing to technical difficulties associated with isolation of osteocytes, studies using scRNA-seq analysis to characterize FGF23-producing osteocytes are lacking. In this study, we characterized osteocytes secreting FGF23 from murine femurs in response to calcitriol (1,25-dihydroxyvitamin D3) using scRNA-seq. We first detected Dmp1, Mepe, and Phex expression in murine osteocytes by in situ hybridization and used these as marker genes of osteocytes. After decalcification, enzyme digestion, and removal of CD45+ cells, femoral bone cells were subjected to scRNA-seq. We identified cell clusters containing osteocytes using marker gene expression. While Fgf23 expression was observed in some osteocytes isolated from femurs of calcitriol-injected mice, no Fgf23 expression was detected in untreated mice. In addition, the expression of several genes which are known to be changed after 1,25-dihydroxyvitamin D3 treatment such as Ccnd2, Fn1, Igfbp7, Pdgfa, and Timp1 was also affected by calcitriol treatment in Fgf23-expressing osteocytes, but not in those lacking Fgf23 expression, even after calcitriol administration. Furthermore, box-and-whisker plots indicated that Fgf23 expression was observed in osteocytes with higher expression levels of the Fam20c, Dmp1, and Phex genes, whose inactivating mutations have been shown to cause FGF23-related hypophosphatemic diseases. These results indicate that osteocytes are heterogeneous with respect to their responsiveness to 1,25-dihydroxyvitamin D3, and sensitivity to 1,25-dihydroxyvitamin D3 is one of the characteristics of osteocytes with Fgf23 expression. It is likely that there is a subpopulation of osteocytes expressing several genes, including Fgf23, involved in phosphate metabolism.
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Affiliation(s)
- Ayako Hanai
- R&D Division, Kyowa Kirin Co., Ltd., Tokyo, Japan,Department of Endocrinology, Metabolism and Hematology, Tokushima University Graduate School of Medical Sciences, Tokushima, Japan,*Correspondence: Ayako Hanai,
| | | | | | | | | | - Masahiro Abe
- Department of Endocrinology, Metabolism and Hematology, Tokushima University Graduate School of Medical Sciences, Tokushima, Japan
| | | | - Seiji Fukumoto
- Department of Molecular Endocrinology, Fujii Memorial Institute of Medical Sciences, Institute of Advanced Medical Sciences, Tokushima University, Tokushima, Japan
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Michigami T. Paracrine and endocrine functions of osteocytes. Clin Pediatr Endocrinol 2023; 32:1-10. [PMID: 36761497 PMCID: PMC9887291 DOI: 10.1297/cpe.2022-0053] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/19/2022] [Accepted: 08/30/2022] [Indexed: 11/04/2022] Open
Abstract
Osteocytes are dendritic-shaped cells embedded in the bone matrix and are terminally differentiated from osteoblasts. Inaccessibility due to their location has hindered the understanding of the molecular functions of osteocytes. However, scientific advances in the past few decades have revealed that osteocytes play critical roles in bone and mineral metabolism through their paracrine and endocrine functions. Sclerostin produced by osteocytes regulates bone formation and resorption by inhibiting Wnt/β-catenin signaling in osteoblast-lineage cells. Receptor activator of nuclear factor κ B ligand (RANKL) derived from osteocytes is essential for osteoclastogenesis and osteoclast activation during postnatal life. Osteocytes also secrete fibroblast growth factor 23 (FGF23), an endocrine FGF that regulates phosphate metabolism mainly by increasing phosphate excretion and decreasing 1, 25-dihydroxyvitamin D production in the kidneys. The regulation of FGF23 production in osteocytes is complex and multifactorial, involving many local and systemic regulators. Antibodies against sclerostin, RANKL, and FGF23 have emerged as new strategies for the treatment of metabolic bone diseases. Improved undrstanding of the paracrine and endocrine functions of osteocytes will provide insight into future therapeutic options.
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Affiliation(s)
- Toshimi Michigami
- Department of Bone and Mineral Research, Research Institute,
Osaka Women’s and Children’s Hospital, Osaka Prefectural Hospital Organization, Osaka,
Japan
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11
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Du S, Zhu C, Ren X, Chen X, Cui X, Guan S. Regulation of secretory pathway kinase or kinase-like proteins in human cancers. Front Immunol 2023; 14:942849. [PMID: 36825005 PMCID: PMC9941534 DOI: 10.3389/fimmu.2023.942849] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2022] [Accepted: 01/24/2023] [Indexed: 02/09/2023] Open
Abstract
Secretory pathway kinase or kinase-like proteins (SPKKPs) are effective in the lumen of the endoplasmic reticulum (ER), Golgi apparatus (GA), and extracellular space. These proteins are involved in secretory signaling pathways and are distinctive from typical protein kinases. Various reports have shown that SPKKPs regulate the tumorigenesis and progression of human cancer via the phosphorylation of various substrates, which is essential in physiological and pathological processes. Emerging evidence has revealed that the expression of SPKKPs in human cancers is regulated by multiple factors. This review summarizes the current understanding of the contribution of SPKKPs in tumorigenesis and the progression of immunity. With the epidemic trend of immunotherapy, targeting SPKKPs may be a novel approach to anticancer therapy. This study briefly discusses the recent advances regarding SPKKPs.
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Affiliation(s)
- Shaonan Du
- Department of Neurosurgery, Shengjing Hospital of China Medical University, Shenyang, China
| | - Chen Zhu
- Department of Neurosurgery, The First Hospital of China Medical University, Shenyang, China
| | - Xiaolin Ren
- Department of Neurosurgery, Shenyang Red Cross Hospital, Shenyang, China
| | - Xin Chen
- Department of Neurosurgery, Shengjing Hospital of China Medical University, Shenyang, China
| | - Xiao Cui
- Department of Neurosurgery, The First Hospital of China Medical University, Shenyang, China
| | - Shu Guan
- Department of Surgical Oncology and Breast Surgery, The First Hospital of China Medical University, Shenyang, China
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12
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Koike T, Mikami T, Tamura JI, Kitagawa H. Altered sulfation status of FAM20C-dependent chondroitin sulfate is associated with osteosclerotic bone dysplasia. Nat Commun 2022; 13:7952. [PMID: 36572689 PMCID: PMC9792594 DOI: 10.1038/s41467-022-35687-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2015] [Accepted: 12/19/2022] [Indexed: 12/27/2022] Open
Abstract
Raine syndrome, a lethal osteosclerotic bone dysplasia in humans, is caused by loss-of-function mutations in FAM20C; however, Fam20c deficiency in mice does not recapitulate the human disorder, so the underlying pathoetiological mechanisms remain poorly understood. Here we show that FAM20C, in addition to the reported casein kinase activity, also fine-tunes the biosynthesis of chondroitin sulfate (CS) chains to impact bone homeostasis. Specifically, FAM20C with Raine-originated mutations loses the ability to interact with chondroitin 4-O-sulfotransferase-1, and is associated with reduced 4-sulfation/6-sulfation (4S/6S) ratio of CS chains and upregulated biomineralization in human osteosarcoma cells. By contrast, overexpressing chondroitin 6-O-sulfotransferase-1 reduces CS 4S/6S ratio, and induces osteoblast differentiation in vitro and higher bone mineral density in transgenic mice. Meanwhile, a potential xylose kinase activity of FAM20C does not impact CS 4S/6S ratio, and is not associated with Raine syndrome mutations. Our results thus implicate CS 4S/6S ratio imbalances caused by FAM20C mutations as a contributor of Raine syndrome etiology.
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Affiliation(s)
- Toshiyasu Koike
- grid.411100.50000 0004 0371 6549Laboratory of Biochemistry, Kobe Pharmaceutical University, Higashinada-Ku, Kobe, 658-8558 Japan
| | - Tadahisa Mikami
- grid.411100.50000 0004 0371 6549Laboratory of Biochemistry, Kobe Pharmaceutical University, Higashinada-Ku, Kobe, 658-8558 Japan
| | - Jun-Ichi Tamura
- grid.265107.70000 0001 0663 5064Department of Agricultural, Life and Environmental Sciences, Faculty of Agriculture, Tottori University, Tottori, 680-8551 Japan
| | - Hiroshi Kitagawa
- grid.411100.50000 0004 0371 6549Laboratory of Biochemistry, Kobe Pharmaceutical University, Higashinada-Ku, Kobe, 658-8558 Japan
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13
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Cipriani C, Minisola S, Colangelo L, DE Martino V, Ferrone F, Biamonte F, Danese V, Sonato C, Santori R, Occhiuto M, Pepe J. FGF23 functions and disease. Minerva Endocrinol (Torino) 2022; 47:437-448. [PMID: 33792238 DOI: 10.23736/s2724-6507.21.03378-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
The main function of fibroblast growth factor 23 (FGF23) is the regulation of phosphate metabolism through its action on the sodium-dependent phosphate cotransporters in the proximal renal tubules. Additionally, FGF23 interacts with vitamin D and parathyroid hormone in a complex metabolic pathway whose detailed mechanisms are still not clear in human physiology and disease. More recently, research has also focused on the understanding of mechanisms of FGF23 action on organs and system other than the kidneys and bone, as well as on its interaction with other metabolic pathways. Collectively, the new evidence are successfully used for the clinical evaluation and management of FGF23-related disorders, for which new therapies with many potential applications are now available.
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Affiliation(s)
- Cristiana Cipriani
- Department of Clinical, Internal, Anesthesiological and Cardiovascular Sciences, Sapienza University, Rome, Italy -
| | - Salvatore Minisola
- Department of Clinical, Internal, Anesthesiological and Cardiovascular Sciences, Sapienza University, Rome, Italy
| | - Luciano Colangelo
- Department of Clinical, Internal, Anesthesiological and Cardiovascular Sciences, Sapienza University, Rome, Italy
| | - Viviana DE Martino
- Department of Clinical, Internal, Anesthesiological and Cardiovascular Sciences, Sapienza University, Rome, Italy
| | - Federica Ferrone
- Department of Clinical, Internal, Anesthesiological and Cardiovascular Sciences, Sapienza University, Rome, Italy
| | - Federica Biamonte
- Department of Clinical, Internal, Anesthesiological and Cardiovascular Sciences, Sapienza University, Rome, Italy
| | - Vittoria Danese
- Department of Clinical, Internal, Anesthesiological and Cardiovascular Sciences, Sapienza University, Rome, Italy
| | - Chiara Sonato
- Department of Clinical, Internal, Anesthesiological and Cardiovascular Sciences, Sapienza University, Rome, Italy
| | - Rachele Santori
- Department of Clinical, Internal, Anesthesiological and Cardiovascular Sciences, Sapienza University, Rome, Italy
| | - Marco Occhiuto
- Department of Clinical, Internal, Anesthesiological and Cardiovascular Sciences, Sapienza University, Rome, Italy
| | - Jessica Pepe
- Department of Clinical, Internal, Anesthesiological and Cardiovascular Sciences, Sapienza University, Rome, Italy
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14
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Agrawal N, Awasthi A, Chakraborty PP, Maiti A. Hypoplastic amelogenesis imperfecta, bilateral nephrolithiasis and FGF-23-mediated hypophosphataemia: a triad of FAM20A-related enamel renal syndrome. BMJ Case Rep 2022; 15:e250514. [PMID: 36351670 PMCID: PMC9644308 DOI: 10.1136/bcr-2022-250514] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Enamel renal syndrome (ERS) due to loss of function (LOF) mutation of FAM20A gene typically consists of hypoplastic amelogenesis imperfecta (AI) and bilateral nephrolithiasis/nephrocalcinosis. Recent evidence suggests that FAM20A interacts with FAM20C and increases its activity; thus LOF mutation of FAM20A leads to impaired FAM20C action. FAM20C, a golgi casein kinase, phosphorylates fibroblast growth factor (FGF)-23, prevents its glycosylation and makes it more susceptible to degradation by furine proteases. Consequently, inactivating mutations of FAM20C lead to increased concentration of bioactive and intact FGF-23 in circulation and resultant hypophosphataemia. LOF mutation of FAM20A, thus, might also be associated with FGF-23-mediated hypophosphataemia; however, such an association has never been reported in the literature. We describe, for the first time, a triad of AI, bilateral nephrolithiasis and FGF-23-mediated hypophosphataemia in LOF mutation of FAM20A. We suggest that serum phosphate should be measured in all patients with ERS to avoid metabolic and skeletal complications of undiagnosed, hence untreated hypophosphataemia.
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Affiliation(s)
- Neeti Agrawal
- Endocrinology & Metabolism, Medical College and Hospital, Kolkata, West Bengal, India
| | - Avivar Awasthi
- Endocrinology & Metabolism, Medical College and Hospital, Kolkata, West Bengal, India
| | | | - Animesh Maiti
- Endocrinology & Metabolism, Medical College and Hospital, Kolkata, West Bengal, India
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15
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Abstract
Inorganic phosphate (Pi) in the mammalian body is balanced by its influx and efflux through the intestines, kidneys, bones, and soft tissues, at which several sodium/Pi co-transporters mediate its active transport. Pi homeostasis is achieved through the complex counter-regulatory feedback balance between fibroblast growth factor 23 (FGF23), 1,25-dihydroxyvitamin D (1,25(OH)2D), and parathyroid hormone. FGF23, which is mainly produced by osteocytes in bone, plays a central role in Pi homeostasis and exerts its effects by binding to the FGF receptor (FGFR) and αKlotho in distant target organs. In the kidneys, the main target, FGF23 promotes the excretion of Pi and suppresses the production of 1,25(OH)2D. Deficient and excess FGF23 result in hyperphosphatemia and hypophosphatemia, respectively. FGF23-related hypophosphatemic rickets/osteomalacia include tumor-induced osteomalacia and various genetic diseases, such as X-linked hypophosphatemic rickets. Coverage by the national health insurance system in Japan for the measurement of FGF23 and the approval of burosumab, an FGF23-neutralizing antibody, have had a significant impact on the diagnosis and treatment of FGF23-related hypophosphatemic rickets/osteomalacia. Some of the molecules responsible for genetic hypophosphatemic rickets/osteomalacia are highly expressed in osteocytes and function as local regulators of FGF23 production. A number of systemic factors also regulate FGF23 levels. Although the mechanisms responsible for Pi sensing in mammals have not yet been elucidated in detail, recent studies have suggested the involvement of FGFR1. The further clarification of the mechanisms by which osteocytes detect Pi levels and regulate FGF23 production will lead to the development of better strategies to treat hyperphosphatemic and hypophosphatemic conditions.
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Affiliation(s)
- Toshimi Michigami
- Department of Bone and Mineral Research, Research Institute, Osaka Women's and Children's Hospital, Osaka 594-1101, Japan
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16
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Pathogenesis of FGF23-Related Hypophosphatemic Diseases Including X-linked Hypophosphatemia. ENDOCRINES 2022. [DOI: 10.3390/endocrines3020025] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Since phosphate is indispensable for skeletal mineralization, chronic hypophosphatemia causes rickets and osteomalacia. Fibroblast growth factor 23 (FGF23), which is mainly produced by osteocytes in bone, functions as the central regulator of phosphate metabolism by increasing the renal excretion of phosphate and suppressing the production of 1,25-dihydroxyvitamin D. The excessive action of FGF23 results in hypophosphatemic diseases, which include a number of genetic disorders such as X-linked hypophosphatemic rickets (XLH) and tumor-induced osteomalacia (TIO). Phosphate-regulating gene homologous to endopeptidase on the X chromosome (PHEX), dentin matrix protein 1 (DMP1), ectonucleotide pyrophosphatase phosphodiesterase-1, and family with sequence similarity 20c, the inactivating variants of which are responsible for FGF23-related hereditary rickets/osteomalacia, are highly expressed in osteocytes, similar to FGF23, suggesting that they are local negative regulators of FGF23. Autosomal dominant hypophosphatemic rickets (ADHR) is caused by cleavage-resistant variants of FGF23, and iron deficiency increases serum levels of FGF23 and the manifestation of symptoms in ADHR. Enhanced FGF receptor (FGFR) signaling in osteocytes is suggested to be involved in the overproduction of FGF23 in XLH and autosomal recessive hypophosphatemic rickets type 1, which are caused by the inactivation of PHEX and DMP1, respectively. TIO is caused by the overproduction of FGF23 by phosphaturic tumors, which are often positive for FGFR. FGF23-related hypophosphatemia may also be associated with McCune-Albright syndrome, linear sebaceous nevus syndrome, and the intravenous administration of iron. This review summarizes current knowledge on the pathogenesis of FGF23-related hypophosphatemic diseases.
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17
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Trombetti A, Al-Daghri N, Brandi ML, Cannata-Andía JB, Cavalier E, Chandran M, Chaussain C, Cipullo L, Cooper C, Haffner D, Harvengt P, Harvey NC, Javaid MK, Jiwa F, Kanis JA, Laslop A, Laurent MR, Linglart A, Marques A, Mindler GT, Minisola S, Yerro MCP, Rosa MM, Seefried L, Vlaskovska M, Zanchetta MB, Rizzoli R. Interdisciplinary management of FGF23-related phosphate wasting syndromes: a Consensus Statement on the evaluation, diagnosis and care of patients with X-linked hypophosphataemia. Nat Rev Endocrinol 2022; 18:366-384. [PMID: 35484227 DOI: 10.1038/s41574-022-00662-x] [Citation(s) in RCA: 40] [Impact Index Per Article: 20.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 03/10/2022] [Indexed: 12/17/2022]
Abstract
X-linked hypophosphataemia (XLH) is the most frequent cause of hypophosphataemia-associated rickets of genetic origin and is associated with high levels of the phosphaturic hormone fibroblast growth factor 23 (FGF23). In addition to rickets and osteomalacia, patients with XLH have a heavy disease burden with enthesopathies, osteoarthritis, pseudofractures and dental complications, all of which contribute to reduced quality of life. This Consensus Statement presents the outcomes of a working group of the European Society for Clinical and Economic Aspects of Osteoporosis, Osteoarthritis and Musculoskeletal Diseases, and provides robust clinical evidence on management in XLH, with an emphasis on patients' experiences and needs. During growth, conventional treatment with phosphate supplements and active vitamin D metabolites (such as calcitriol) improves growth, ameliorates leg deformities and dental manifestations, and reduces pain. The continuation of conventional treatment in symptom-free adults is still debated. A novel therapeutic approach is the monoclonal anti-FGF23 antibody burosumab. Although promising, further studies are required to clarify its long-term efficacy, particularly in adults. Given the diversity of symptoms and complications, an interdisciplinary approach to management is of paramount importance. The focus of treatment should be not only on the physical manifestations and challenges associated with XLH and other FGF23-mediated hypophosphataemia syndromes, but also on the major psychological and social impact of the disease.
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Affiliation(s)
- Andrea Trombetti
- Division of Bone Diseases, Department of Medicine, Geneva University Hospitals and Faculty of Medicine, Geneva, Switzerland
- Division of Geriatrics, Department of Rehabilitation and Geriatrics, Geneva University Hospitals and Faculty of Medicine, Geneva, Switzerland
| | - Nasser Al-Daghri
- Chair for Biomarkers of Chronic Diseases, Biochemistry Department, College of Science, King Saud University, Riyadh, Kingdom of Saudi Arabia
| | | | - Jorge B Cannata-Andía
- Hospital Universitario Central de Asturias (HUCA), Oviedo, Spain
- Universidad de Oviedo, Oviedo, Spain
- Instituto de Investigación Sanitaria del Principado de Asturias (ISPA), Oviedo, Spain
- Retic REDinREN-RICORS, 2040-ISCIII, Madrid, Spain
| | - Etienne Cavalier
- Department of Clinical Chemistry, University of Liege, CHU de Liège, Liège, Belgium
| | - Manju Chandran
- Complicated Metabolic Bone Disorders Clinic, Osteoporosis and Bone Metabolism Unit, Department of Endocrinology, Singapore General Hospital, Singapore, Singapore
| | - Catherine Chaussain
- Université de Paris, Institut des maladies musculo-squelettiques, URP2496, UFR Odontologie, Montrouge, France
- AP-HP, FHU DDS-Net, Centre de Référence des Maladies Rares du Métabolisme du Calcium et du Phosphore, Service médecine bucco-dentaire, Hôpital Bretonneau, GH Paris Nord Université de Paris, Paris, France
| | - Lucia Cipullo
- Patient representative with XLH, Geneva, Switzerland
| | - Cyrus Cooper
- MRC Lifecourse Epidemiology Centre, University of Southampton, Southampton, UK
- NIHR Southampton Biomedical Research Centre, University of Southampton and University Hospital Southampton NHS Foundation Trust, Southampton, UK
- NIHR Oxford Biomedical Research Centre, University of Oxford, Oxford, UK
| | - Dieter Haffner
- Department of Paediatric Kidney, Liver and Metabolic Diseases, Hannover Medical School, Hannover, Germany
| | - Pol Harvengt
- XLH Belgium, Belgian association of patients with XLH (a member of the International XLH Alliance), Waterloo, Belgium
| | - Nicholas C Harvey
- MRC Lifecourse Epidemiology Centre, University of Southampton, Southampton, UK
- NIHR Southampton Biomedical Research Centre, University of Southampton and University Hospital Southampton NHS Foundation Trust, Southampton, UK
| | | | - Famida Jiwa
- Chair of the Committee of Patients Societies at the International Osteoporosis Foundation, Osteoporosis Canada, Toronto, Canada
| | - John A Kanis
- Mary McKillop Institute for Health Research, Australian Catholic University, Melbourne, Australia
- Centre for Metabolic Bone Diseases, University of Sheffield Medical School, Sheffield, UK
| | - Andrea Laslop
- Scientific Office, Federal Office for Safety in Health Care, Vienna, Austria
| | - Michaël R Laurent
- Centre for Metabolic Bone Diseases, University Hospitals Leuven, Leuven, Belgium
| | - Agnès Linglart
- Paris-Saclay University, INSERM U1185, Le Kremlin-Bicêtre, France
- AP-HP, endocrinology and diabetes for children, Reference centre for rare diseases of calcium and phosphate metabolism, OSCAR network, Platform of expertise for rare diseases of Paris Saclay Hospital, Bicêtre Paris Saclay Hospital, Le Kremlin-Bicêtre, France
| | - Andréa Marques
- Rheumatology Department, Centro Hospitalar Universitário de Coimbra, Coimbra, Portugal
- Health Sciences Research Unit: Nursing (UICiSA:E), Nursing School of Coimbra, Coimbra, Portugal
| | - Gabriel T Mindler
- Department of Paediatric Orthopaedics, Orthopaedic Hospital Speising, Vienna, Austria
- Vienna Bone and Growth Center, Vienna, Austria
| | - Salvatore Minisola
- Department of Clinical, Internal, Anaesthesiologic and Cardiovascular Sciences, 'Sapienza', Rome University, Rome, Italy
| | | | - Mario Miguel Rosa
- Departamento de Neurociências, Laboratório de Farmacologia Clínica E Terapêutica Faculdade de Medicina da Universidade de Lisboa, Lisbon, Portugal
| | - Lothar Seefried
- Orthopedic Department, University of Würzburg, Würzburg, Germany
| | - Mila Vlaskovska
- Medical Faculty, Department of Pharmacology, Medical University Sofia, Sofia, Bulgaria
| | - María Belén Zanchetta
- Instituto de Investigaciones Metabólicas (IDIM), Universidad del Salvador, Buenos Aires, Argentina
| | - René Rizzoli
- Division of Bone Diseases, Department of Medicine, Geneva University Hospitals and Faculty of Medicine, Geneva, Switzerland.
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18
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Jin JY, Zhang LY, Guo S, Tang K, Zeng L, Xiang R, Liang JY. Genetic analysis combined with 3D-printing assistant surgery in diagnosis and treatment for an X-linked hypophosphatemia patient. J Clin Lab Anal 2022; 36:e24243. [PMID: 35106857 PMCID: PMC8906030 DOI: 10.1002/jcla.24243] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2021] [Revised: 12/13/2021] [Accepted: 12/14/2021] [Indexed: 11/05/2022] Open
Abstract
Background Hypophosphatemia is mainly characterized by hypophosphatemia and a low level of 1alpha,25‐Dihydroxyvitamin D2 (1,25‐(OH)2D2) and/or 1alpha,25‐Dihydroxyvitamin D3 (1,25‐(OH)2D3) in the blood. Previous studies have demonstrated that variants in PHEX and FGF23 are primarily responsible for this disease. Although patients with variants of these two genes share almost the same symptoms, they exhibit the different hereditary pattern, X‐link dominant and autosome dominant, respectively. Three‐dimensional (3D) printing is a method which can accurately reconstruct physical objects, and its applications in orthopedics can contribute to realizing a more accurate surgical performance and a better outcome. Methods An X‐linked hypophosphatemia (XLH) family was recruited, with four patients across three generations. We screened candidate genes and filtered a duplication variant in PHEX. Variant analysis and co‐segregation confirmation were then performed. Before the operation of our patient, a digital model of our patient's leg had been rebuilt upon the CT scan data, and a polylactic acid (PLA) model had been 3D‐printed. Results A novel duplication PHEX variant c.574dupG (p.A192GfsX20) was identified in a family with XLH. Its pathogenicity was confirmed by the co‐segregation assay and online bioinformatics database. The preoperative plan was made with the help of the PLA model. Then, arch osteotomy and transverse osteotomy were performed under the guidance of the previous simulation. The appearance of the surgical‐intervened leg was satisfactory. Conclusions This study identified a novel PHEX variant and showed that 3D printing tech is a very promising approach for corrective osteotomies.
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Affiliation(s)
- Jie-Yuan Jin
- Department of Orthopaedics, Xiangya Hospital of Central South University, Changsha, China.,School of Life Sciences, Central South University, Changsha, China.,Hunan Key Laboratory of Animal Models for Human Diseases, Central South University, Changsha, China
| | - Li-Yang Zhang
- Department of Neurosurgery, Xiangya Hospital, Central South University, Changsha, China.,Hunan Key Laboratory of Medical Genetics, School of Life Sciences, Central South University, Changsha, China
| | - Shuai Guo
- School of Life Sciences, Central South University, Changsha, China
| | - Ke Tang
- School of Life Sciences, Central South University, Changsha, China.,Hunan Key Laboratory of Animal Models for Human Diseases, Central South University, Changsha, China.,Hunan Key Laboratory of Medical Genetics, School of Life Sciences, Central South University, Changsha, China
| | - Lei Zeng
- Department of Orthopaedics, Xiangya Hospital of Central South University, Changsha, China.,Hunan Key Laboratory of Medical Genetics, School of Life Sciences, Central South University, Changsha, China
| | - Rong Xiang
- Department of Orthopaedics, Xiangya Hospital of Central South University, Changsha, China.,School of Life Sciences, Central South University, Changsha, China.,Hunan Key Laboratory of Animal Models for Human Diseases, Central South University, Changsha, China.,Hunan Key Laboratory of Medical Genetics, School of Life Sciences, Central South University, Changsha, China
| | - Jie-Yu Liang
- Department of Orthopaedics, Xiangya Hospital of Central South University, Changsha, China.,Hunan Key Laboratory of Medical Genetics, School of Life Sciences, Central South University, Changsha, China
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19
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Rush ET, Johnson B, Aradhya S, Beltran D, Bristow SL, Eisenbeis S, Guerra NE, Krolczyk S, Miller N, Morales A, Ramesan P, Sarafrazi S, Truty R, Dahir K. Molecular Diagnoses of X-Linked and Other Genetic Hypophosphatemias: Results From a Sponsored Genetic Testing Program. J Bone Miner Res 2022; 37:202-214. [PMID: 34633109 PMCID: PMC9298723 DOI: 10.1002/jbmr.4454] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/05/2021] [Revised: 09/27/2021] [Accepted: 10/02/2021] [Indexed: 12/20/2022]
Abstract
X-linked hypophosphatemia (XLH), a dominant disorder caused by pathogenic variants in the PHEX gene, affects both sexes of all ages and results in elevated serum fibroblast growth factor 23 (FGF23) and below-normal serum phosphate. In XLH, rickets, osteomalacia, short stature, and lower limb deformity may be present with muscle pain and/or weakness/fatigue, bone pain, joint pain/stiffness, hearing difficulty, enthesopathy, osteoarthritis, and dental abscesses. Invitae and Ultragenyx collaborated to provide a no-charge sponsored testing program using a 13-gene next-generation sequencing panel to confirm clinical XLH or aid diagnosis of suspected XLH/other genetic hypophosphatemia. Individuals aged ≥6 months with clinical XLH or suspected genetic hypophosphatemia were eligible. Of 831 unrelated individuals tested between February 2019 and June 2020 in this cross-sectional study, 519 (62.5%) individuals had a pathogenic or likely pathogenic variant in PHEX (PHEX-positive). Among the 312 PHEX-negative individuals, 38 received molecular diagnoses in other genes, including ALPL, CYP27B1, ENPP1, and FGF23; the remaining 274 did not have a molecular diagnosis. Among 319 patients with a provider-reported clinical diagnosis of XLH, 88.7% (n = 283) had a reportable PHEX variant; 81.5% (n = 260) were PHEX-positive. The most common variant among PHEX-positive individuals was an allele with both the gain of exons 13-15 and c.*231A>G (3'UTR variant) (n = 66/519). Importantly, over 80% of copy number variants would have been missed by traditional microarray analysis. A positive molecular diagnosis in 41 probands (4.9%; 29 PHEX positive, 12 non-PHEX positive) resulted in at least one family member receiving family testing. Additional clinical or family member information resulted in variant(s) of uncertain significance (VUS) reclassification to pathogenic/likely pathogenic (P/LP) in 48 individuals, highlighting the importance of segregation and clinical data. In one of the largest XLH genetic studies to date, 65 novel PHEX variants were identified and a high XLH diagnostic yield demonstrated broad insight into the genetic basis of XLH. © 2021 The Authors. Journal of Bone and Mineral Research published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research (ASBMR).
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Affiliation(s)
- Eric T Rush
- Children's Mercy Kansas City, Kansas City, MO, USA.,Department of Pediatrics, University of Missouri - Kansas City School of Medicine, Kansas City, MO, USA.,Department of Internal Medicine, University of Kansas Medical Center, Kansas City, KS, USA
| | | | | | | | | | | | - Norma E Guerra
- Department of Pediatric Nephrology, Hospital General del Centro Médico Nacional «La Raza», Instituto Mexicano del Seguro Social (IMSS), Ciudad de México, Mexico
| | | | | | | | | | | | | | - Kathryn Dahir
- Program for Metabolic Bone Disorders, Vanderbilt University Medical Center (VUMC), Nashville, TN, USA
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20
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Xu R, Tan H, Zhang J, Yuan Z, Xie Q, Zhang L. Fam20C in Human Diseases: Emerging Biological Functions and Therapeutic Implications. Front Mol Biosci 2022; 8:790172. [PMID: 34988120 PMCID: PMC8721277 DOI: 10.3389/fmolb.2021.790172] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2021] [Accepted: 11/08/2021] [Indexed: 02/05/2023] Open
Abstract
Fam20C, a typical member of Fam20 family, has been well-known as a Golgi casein kinase, which is closely associated with Raine Syndrome (RS). It can phosphorylate many secreted proteins and multiple substrates, and thereby plays a crucial role in biological functions. More importantly, Fam20C has also been found to enhance the metastasis of several types of human cancers, such as breast cancer, indicating that Fam20C may be a promising therapeutic target. Accordingly, some small-molecule inhibitors of Fam20C have been reported in cancer. Taken together, these inspiring findings would shed new light on exploiting Fam20C as a potential therapeutic target and inhibiting Fam20C with small-molecule compounds would provide a clue on discovery of more candidate small-molecule drugs for fighting with human diseases.
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Affiliation(s)
- Rongsheng Xu
- Department of Stomatology, Zigong First People's Hospital, Zigong, China
| | - Huidan Tan
- State Key Laboratory of Biotherapy and Cancer Center, West China Hospital, Sichuan University, Chengdu, China
| | - Jiahui Zhang
- State Key Laboratory of Biotherapy and Cancer Center, West China Hospital, Sichuan University, Chengdu, China
| | - Zhaoxin Yuan
- State Key Laboratory of Biotherapy and Cancer Center, West China Hospital, Sichuan University, Chengdu, China.,Sichuan Engineering Research Center for Biomimetic Synthesis of Natural Drugs, School of Life Science and Engineering, Southwest Jiaotong University, Chengdu, China
| | - Qiang Xie
- State Key Laboratory of Biotherapy and Cancer Center, West China Hospital, Sichuan University, Chengdu, China
| | - Lan Zhang
- Sichuan Engineering Research Center for Biomimetic Synthesis of Natural Drugs, School of Life Science and Engineering, Southwest Jiaotong University, Chengdu, China
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Abstract
Osteocytes are dendritic cells in the mineralized bone matrix that descend from osteoblasts. They play critical roles in controlling bone mass through the production of sclerostin, an inhibitor of bone formation, and receptor activator of nuclear factor κ B ligand, an inducer of osteoblastic bone resorption. Osteocytes also govern phosphate homeostasis through the production of fibroblast growth factor 23 (FGF23), which lowers serum phosphate levels by increasing renal phosphate excretion and reducing the synthesis of 1,25-dihydroxyvitamin D (1,25(OH)2D), an active metabolite of vitamin D. The production of FGF23 in osteocytes is regulated by various local and systemic factors. Phosphate-regulating gene homologous to endopeptidase on X chromosome (PHEX), dentin matrix protein 1 (DMP1), and family with sequence similarity 20, member C function as local negative regulators of FGF23 production in osteocytes, and their inactivation causes the overproduction of FGF23 and hypophosphatemia. Sclerostin has been suggested to regulate the production of FGF23, which may link the two functions of osteocytes, namely, the control of bone mass and regulation of phosphate homeostasis. Systemic regulators of FGF23 production include 1,25(OH)2D, phosphate, parathyroid hormone, insulin, iron, and inflammation. Therefore, the regulation of FGF23 in osteocytes is complex and multifactorial. Recent mouse studies have suggested that decreases in serum phosphate levels from youth to adulthood are caused by growth-related increases in FGF23 production by osteocytes, which are associated with the down-regulation of Phex and Dmp1.
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Haffner D, Leifheit-Nestler M, Grund A, Schnabel D. Rickets guidance: part II-management. Pediatr Nephrol 2022; 37:2289-2302. [PMID: 35352187 PMCID: PMC9395459 DOI: 10.1007/s00467-022-05505-5] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/30/2021] [Revised: 02/08/2022] [Accepted: 02/09/2022] [Indexed: 11/28/2022]
Abstract
Here, we discuss the management of different forms of rickets, including new therapeutic approaches based on recent guidelines. Management includes close monitoring of growth, the degree of leg bowing, bone pain, serum phosphate, calcium, alkaline phosphatase as a surrogate marker of osteoblast activity and thus degree of rickets, parathyroid hormone, 25-hydroxyvitamin D3, and calciuria. An adequate calcium intake and normal 25-hydroxyvitamin D3 levels should be assured in all patients. Children with calcipenic rickets require the supplementation or pharmacological treatment with native or active vitamin D depending on the underlying pathophysiology. Treatment of phosphopenic rickets depends on the underlying pathophysiology. Fibroblast-growth factor 23 (FGF23)-associated hypophosphatemic rickets was historically treated with frequent doses of oral phosphate salts in combination with active vitamin D, whereas tumor-induced osteomalacia (TIO) should primarily undergo tumor resection, if possible. Burosumab, a fully humanized FGF23-antibody, was recently approved for treatment of X-linked hypophosphatemia (XLH) and TIO and shown to be superior for treatment of XLH compared to conventional treatment. Forms of hypophosphatemic rickets independent of FGF23 due to genetic defects of renal tubular phosphate reabsorption are treated with oral phosphate only, since they are associated with excessive 1,25-dihydroxyvitamin D production. Finally, forms of hypophosphatemic rickets caused by Fanconi syndrome, such as nephropathic cystinosis and Dent disease require disease-specific treatment in addition to phosphate supplements and active vitamin D. Adjustment of medication should be done with consideration of treatment-associated side effects, including diarrhea, gastrointestinal discomfort, hypercalciuria, secondary hyperparathyroidism, and development of nephrocalcinosis or nephrolithiasis.
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Affiliation(s)
- Dieter Haffner
- Department of Pediatric Kidney, Liver and Metabolic Diseases, Hannover Medical School, Carl-Neuberg-Str. 1, 30625, Hannover, Germany. .,Pediatric Research Center, Hannover Medical School, Carl-Neuberg-Str. 1, 30625, Hannover, Germany.
| | - Maren Leifheit-Nestler
- Department of Pediatric Kidney, Liver and Metabolic Diseases, Hannover Medical School, Carl-Neuberg-Str. 1, 30625 Hannover, Germany ,Pediatric Research Center, Hannover Medical School, Carl-Neuberg-Str. 1, 30625 Hannover, Germany
| | - Andrea Grund
- Department of Pediatric Kidney, Liver and Metabolic Diseases, Hannover Medical School, Carl-Neuberg-Str. 1, 30625 Hannover, Germany ,Pediatric Research Center, Hannover Medical School, Carl-Neuberg-Str. 1, 30625 Hannover, Germany
| | - Dirk Schnabel
- Center for Chronically Sick Children, Pediatric Endocrinology, Charitè, University Medicine, Berlin, Germany
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Haffner D, Leifheit-Nestler M, Grund A, Schnabel D. Rickets guidance: part I-diagnostic workup. Pediatr Nephrol 2022; 37:2013-2036. [PMID: 34910242 PMCID: PMC9307538 DOI: 10.1007/s00467-021-05328-w] [Citation(s) in RCA: 19] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/07/2021] [Revised: 09/30/2021] [Accepted: 10/01/2021] [Indexed: 01/22/2023]
Abstract
Rickets is a disease of the growing child arising from alterations in calcium and phosphate homeostasis resulting in impaired apoptosis of hypertrophic chondrocytes in the growth plate. Its symptoms depend on the patients' age, duration of disease, and underlying disorder. Common features include thickened wrists and ankles due to widened metaphyses, growth failure, bone pain, muscle weakness, waddling gait, and leg bowing. Affected infants often show delayed closure of the fontanelles, frontal bossing, and craniotabes. The diagnosis of rickets is based on the presence of these typical clinical symptoms and radiological findings on X-rays of the wrist or knee, showing metaphyseal fraying and widening of growth plates, in conjunction with elevated serum levels of alkaline phosphatase. Nutritional rickets due to vitamin D deficiency and/or dietary calcium deficiency is the most common cause of rickets. Currently, more than 20 acquired or hereditary causes of rickets are known. The latter are due to mutations in genes involved in vitamin D metabolism or action, renal phosphate reabsorption, or synthesis, or degradation of the phosphaturic hormone fibroblast growth factor 23 (FGF23). There is a substantial overlap in the clinical features between the various entities, requiring a thorough workup using biochemical analyses and, if necessary, genetic tests. Part I of this review focuses on the etiology, pathophysiology and clinical findings of rickets followed by the presentation of a diagnostic approach for correct diagnosis. Part II focuses on the management of rickets, including new therapeutic approaches based on recent clinical practice guidelines.
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Affiliation(s)
- Dieter Haffner
- Department of Pediatric Kidney, Liver and Metabolic Diseases, Hannover Medical School, Carl-Neuberg-Str. 1, 30625, Hannover, Germany. .,Hannover Medical School, Pediatric Research Center, Carl-Neuberg-Str. 1, 30625, Hannover, Germany.
| | - Maren Leifheit-Nestler
- Department of Pediatric Kidney, Liver and Metabolic Diseases, Hannover Medical School, Carl-Neuberg-Str. 1, 30625 Hannover, Germany ,Hannover Medical School, Pediatric Research Center, Carl-Neuberg-Str. 1, 30625 Hannover, Germany
| | - Andrea Grund
- Department of Pediatric Kidney, Liver and Metabolic Diseases, Hannover Medical School, Carl-Neuberg-Str. 1, 30625 Hannover, Germany ,Hannover Medical School, Pediatric Research Center, Carl-Neuberg-Str. 1, 30625 Hannover, Germany
| | - Dirk Schnabel
- Center for Chronically Sick Children, Pediatric Endocrinology, University Medicine, Charitè Berlin, Germany
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Yamazaki M, Michigami T. Osteocytes and the pathogenesis of hypophosphatemic rickets. Front Endocrinol (Lausanne) 2022; 13:1005189. [PMID: 36246908 PMCID: PMC9556901 DOI: 10.3389/fendo.2022.1005189] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/28/2022] [Accepted: 09/15/2022] [Indexed: 11/13/2022] Open
Abstract
Since phosphorus is a component of hydroxyapatite, its prolonged deprivation affects bone mineralization. Fibroblast growth factor 23 (FGF23) is essential for maintaining phosphate homeostasis and is mainly produced by osteocytes. FGF23 increases the excretion of inorganic phosphate (Pi) and decreases the production of 1,25-dihydroxyvitamin D in the kidneys. Osteocytes are cells of osteoblastic lineage that have undergone terminal differentiation and become embedded in mineralized bone matrix. Osteocytes express FGF23 and other multiple genes responsible for hereditary hypophosphatemic rickets, which include phosphate-regulating gene homologous to endopeptidase on X chromosome (PHEX), dentin matrix protein 1 (DMP1), and family with sequence similarity 20, member C (FAM20C). Since inactivating mutations in PHEX, DMP1, and FAM20C boost the production of FGF23, these molecules might be considered as local negative regulators of FGF23. Mouse studies have suggested that enhanced FGF receptor (FGFR) signaling is involved in the overproduction of FGF23 in PHEX-deficient X-linked hypophosphatemic rickets (XLH) and DMP1-deficient autosomal recessive hypophosphatemic rickets type 1. Since FGFR is involved in the transduction of signals evoked by extracellular Pi, Pi sensing in osteocytes may be abnormal in these diseases. Serum levels of sclerostin, an inhibitor Wnt/β-catenin signaling secreted by osteocytes, are increased in XLH patients, and mouse studies have suggested the potential of inhibiting sclerostin as a new therapeutic option for the disease. The elucidation of complex abnormalities in the osteocytes of FGF23-related hypophosphatemic diseases will provide a more detailed understanding of their pathogenesis and more effective treatments.
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FAM20C Overview: Classic and Novel Targets, Pathogenic Variants and Raine Syndrome Phenotypes. Int J Mol Sci 2021; 22:ijms22158039. [PMID: 34360805 PMCID: PMC8348777 DOI: 10.3390/ijms22158039] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2021] [Revised: 07/16/2021] [Accepted: 07/18/2021] [Indexed: 12/24/2022] Open
Abstract
FAM20C is a gene coding for a protein kinase that targets S-X-E/pS motifs on different phosphoproteins belonging to diverse tissues. Pathogenic variants of FAM20C are responsible for Raine syndrome (RS), initially described as a lethal and congenital osteosclerotic dysplasia characterized by generalized atherosclerosis with periosteal bone formation, characteristic facial dysmorphisms and intracerebral calcifications. The aim of this review is to give an overview of targets and variants of FAM20C as well as RS aspects. We performed a wide phenotypic review focusing on clinical aspects and differences between all lethal (LRS) and non-lethal (NLRS) reported cases, besides the FAM20C pathogenic variant description for each. As new targets of FAM20C kinase have been identified, we reviewed FAM20C targets and their functions in bone and other tissues, with emphasis on novel targets not previously considered. We found the classic lethal and milder non-lethal phenotypes. The milder phenotype is defined by a large spectrum ranging from osteonecrosis to osteosclerosis with additional congenital defects or intellectual disability in some cases. We discuss our current understanding of FAM20C deficiency, its mechanism in RS through classic FAM20C targets in bone tissue and its potential biological relevance through novel targets in non-bone tissues.
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Papadopoulou A, Bountouvi E, Karachaliou FE. The Molecular Basis of Calcium and Phosphorus Inherited Metabolic Disorders. Genes (Basel) 2021; 12:genes12050734. [PMID: 34068220 PMCID: PMC8153134 DOI: 10.3390/genes12050734] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2021] [Revised: 04/30/2021] [Accepted: 05/05/2021] [Indexed: 02/07/2023] Open
Abstract
Calcium (Ca) and Phosphorus (P) hold a leading part in many skeletal and extra-skeletal biological processes. Their tight normal range in serum mirrors their critical role in human well-being. The signalling “voyage” starts at Calcium Sensing Receptor (CaSR) localized on the surface of the parathyroid glands, which captures the “oscillations” of extracellular ionized Ca and transfers the signal downstream. Parathyroid hormone (PTH), Vitamin D, Fibroblast Growth Factor (FGF23) and other receptors or ion-transporters, work synergistically and establish a highly regulated signalling circuit between the bone, kidneys, and intestine to ensure the maintenance of Ca and P homeostasis. Any deviation from this well-orchestrated scheme may result in mild or severe pathologies expressed by biochemical and/or clinical features. Inherited disorders of Ca and P metabolism are rare. However, delayed diagnosis or misdiagnosis may cost patient’s quality of life or even life expectancy. Unravelling the thread of the molecular pathways involving Ca and P signaling, we can better understand the link between genetic alterations and biochemical and/or clinical phenotypes and help in diagnosis and early therapeutic intervention.
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The ABCs of the atypical Fam20 secretory pathway kinases. J Biol Chem 2021; 296:100267. [PMID: 33759783 PMCID: PMC7948968 DOI: 10.1016/j.jbc.2021.100267] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2020] [Revised: 01/05/2021] [Accepted: 01/06/2021] [Indexed: 12/12/2022] Open
Abstract
The study of extracellular phosphorylation was initiated in late 19th century when the secreted milk protein, casein, and egg-yolk protein, phosvitin, were shown to be phosphorylated. However, it took more than a century to identify Fam20C, which phosphorylates both casein and phosvitin under physiological conditions. This kinase, along with its family members Fam20A and Fam20B, defined a new family with altered amino acid sequences highly atypical from the canonical 540 kinases comprising the kinome. Fam20B is a glycan kinase that phosphorylates xylose residues and triggers peptidoglycan biosynthesis, a role conserved from sponges to human. The protein kinase, Fam20C, conserved from nematodes to humans, phosphorylates well over 100 substrates in the secretory pathway with overall functions postulated to encompass endoplasmic reticulum homeostasis, nutrition, cardiac function, coagulation, and biomineralization. The preferred phosphorylation motif of Fam20C is SxE/pS, and structural studies revealed that related member Fam20A allosterically activates Fam20C by forming a heterodimeric/tetrameric complex. Fam20A, a pseudokinase, is observed only in vertebrates. Loss-of-function genetic alterations in the Fam20 family lead to human diseases such as amelogenesis imperfecta, nephrocalcinosis, lethal and nonlethal forms of Raine syndrome with major skeletal defects, and altered phosphate homeostasis. Together, these three members of the Fam20 family modulate a diverse network of secretory pathway components playing crucial roles in health and disease. The overarching theme of this review is to highlight the progress that has been made in the emerging field of extracellular phosphorylation and the key roles secretory pathway kinases play in an ever-expanding number of cellular processes.
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Koumakis E, Cormier C, Roux C, Briot K. The Causes of Hypo- and Hyperphosphatemia in Humans. Calcif Tissue Int 2021; 108:41-73. [PMID: 32285168 DOI: 10.1007/s00223-020-00664-9] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/04/2019] [Accepted: 01/20/2020] [Indexed: 12/11/2022]
Abstract
Phosphate homeostasis involves several major organs that are the skeleton, the intestine, the kidney, and parathyroid glands. Major regulators of phosphate homeostasis are parathormone, fibroblast growth factor 23, 1,25-dihydroxyvitamin D, which respond to variations of serum phosphate levels and act to increase or decrease intestinal absorption and renal tubular reabsorption, through the modulation of expression of transcellular transporters at the intestinal and/or renal tubular level. Any acquired or genetic dysfunction in these major organs or regulators may induce hypo- or hyperphosphatemia. The causes of hypo- and hyperphosphatemia are numerous. This review develops the main causes of acquired and genetic hypo- and hyperphosphatemia.
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Affiliation(s)
- Eugénie Koumakis
- Reference Center for Rare Disorders of Calcium and Phosphate Metabolism, Reference Center for Rare Genetic Bone Disorders, OSCAR Filière, Rheumatology Department, Cochin Hospital, AP-HP Centre-Paris University, 27 Rue du Faubourg Saint-Jacques, 75014, Paris, France.
| | - Catherine Cormier
- Reference Center for Rare Disorders of Calcium and Phosphate Metabolism, Reference Center for Rare Genetic Bone Disorders, OSCAR Filière, Rheumatology Department, Cochin Hospital, AP-HP Centre-Paris University, 27 Rue du Faubourg Saint-Jacques, 75014, Paris, France
| | - Christian Roux
- Reference Center for Rare Disorders of Calcium and Phosphate Metabolism, Reference Center for Rare Genetic Bone Disorders, OSCAR Filière, Rheumatology Department, Cochin Hospital, AP-HP Centre-Paris University, 27 Rue du Faubourg Saint-Jacques, 75014, Paris, France
| | - Karine Briot
- Reference Center for Rare Disorders of Calcium and Phosphate Metabolism, Reference Center for Rare Genetic Bone Disorders, OSCAR Filière, Rheumatology Department, Cochin Hospital, AP-HP Centre-Paris University, 27 Rue du Faubourg Saint-Jacques, 75014, Paris, France
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Abstract
Great strides over the past few decades have increased our understanding of the pathophysiology of hypophosphatemic disorders. Phosphate is critically important to a variety of physiologic processes, including skeletal growth, development and mineralization, as well as DNA, RNA, phospholipids, and signaling pathways. Consequently, hypophosphatemic disorders have effects on multiple systems, and may cause a variety of nonspecific signs and symptoms. The acute effects of hypophosphatemia include neuromuscular symptoms and compromise. However, the dominant effects of chronic hypophosphatemia are the effects on musculoskeletal function including rickets, osteomalacia and impaired growth during childhood. While the most common causes of chronic hypophosphatemia in children are congenital, some acquired conditions also result in hypophosphatemia during childhood through a variety of mechanisms. Improved understanding of the pathophysiology of these congenital conditions has led to novel therapeutic approaches. This article will review the pathophysiologic causes of congenital hypophosphatemia, their clinical consequences and medical therapy.
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Affiliation(s)
- Erik Allen Imel
- Division of Endocrinology, Departments of Medicine and Pediatrics, Indiana University School of Medicine, 1120 West Michigan Street, Gatch Building Room 365, Indianapolis, IN, 46112, USA.
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Abstract
FGF23 is a phosphotropic hormone produced by the bone. FGF23 works by binding to the FGF receptor-Klotho complex. Klotho is expressed in several limited tissues including the kidney and parathyroid glands. This tissue-restricted expression of Klotho is believed to determine the target organs of FGF23. FGF23 reduces serum phosphate by suppressing the expression of type 2a and 2c sodium-phosphate cotransporters in renal proximal tubules. FGF23 also decreases 1,25-dihydroxyvitamin D levels by regulating the expression of vitamin D-metabolizing enzymes, which results in reduced intestinal phosphate absorption. Excessive actions of FGF23 cause several types of hypophosphatemic rickets/osteomalacia characterized by impaired mineralization of bone matrix. In contrast, deficient actions of FGF23 result in hyperphosphatemic tumoral calcinosis with high 1,25-dihydroxyvitamin D levels. These results indicate that FGF23 is a physiological regulator of phosphate and vitamin D metabolism and indispensable for the maintenance of serum phosphate levels.
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Khor JM, Ettensohn CA. Transcription Factors of the Alx Family: Evolutionarily Conserved Regulators of Deuterostome Skeletogenesis. Front Genet 2020; 11:569314. [PMID: 33329706 PMCID: PMC7719703 DOI: 10.3389/fgene.2020.569314] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2020] [Accepted: 10/19/2020] [Indexed: 12/13/2022] Open
Abstract
Members of the alx gene family encode transcription factors that contain a highly conserved Paired-class, DNA-binding homeodomain, and a C-terminal OAR/Aristaless domain. Phylogenetic and comparative genomic studies have revealed complex patterns of alx gene duplications during deuterostome evolution. Remarkably, alx genes have been implicated in skeletogenesis in both echinoderms and vertebrates. In this review, we provide an overview of current knowledge concerning alx genes in deuterostomes. We highlight their evolutionarily conserved role in skeletogenesis and draw parallels and distinctions between the skeletogenic gene regulatory circuitries of diverse groups within the superphylum.
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Affiliation(s)
- Jian Ming Khor
- Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, PA, United States
| | - Charles A Ettensohn
- Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, PA, United States
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Serna J, Bergwitz C. Importance of Dietary Phosphorus for Bone Metabolism and Healthy Aging. Nutrients 2020; 12:E3001. [PMID: 33007883 PMCID: PMC7599912 DOI: 10.3390/nu12103001] [Citation(s) in RCA: 43] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2020] [Revised: 09/25/2020] [Accepted: 09/26/2020] [Indexed: 12/13/2022] Open
Abstract
Inorganic phosphate (Pi) plays a critical function in many tissues of the body: for example, as part of the hydroxyapatite in the skeleton and as a substrate for ATP synthesis. Pi is the main source of dietary phosphorus. Reduced bioavailability of Pi or excessive losses in the urine causes rickets and osteomalacia. While critical for health in normal amounts, dietary phosphorus is plentiful in the Western diet and is often added to foods as a preservative. This abundance of phosphorus may reduce longevity due to metabolic changes and tissue calcifications. In this review, we examine how dietary phosphorus is absorbed in the gut, current knowledge about Pi sensing, and endocrine regulation of Pi levels. Moreover, we also examine the roles of Pi in different tissues, the consequences of low and high dietary phosphorus in these tissues, and the implications for healthy aging.
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Affiliation(s)
- Juan Serna
- Yale College, Yale University, New Haven, CT 06511, USA;
| | - Clemens Bergwitz
- Section of Endocrinology and Metabolism, Department of Internal Medicine, Yale School of Medicine, New Haven, CT 06519, USA
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El-Dessouky SH, Abdel-Hamid MS, Abdel-Ghafar SF, Aboulghar MM, Gaafar HM, Fouad M, Ahmed AH, Abdel-Salam GMH. Raine syndrome: Prenatal diagnosis based on recognizable fetal facial features and characteristic intracranial calcification. Prenat Diagn 2020; 40:1578-1597. [PMID: 32833257 DOI: 10.1002/pd.5818] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2020] [Revised: 08/20/2020] [Accepted: 08/20/2020] [Indexed: 01/21/2023]
Abstract
OBJECTIVE The purpose of this study was to elucidate the facial morphology and the pattern of internal malformations in three fetuses with RS born to first cousins of Egyptian decent. METHODS The fetal ultrasonography findings were highly suggestive of RS leading to targeted Sanger sequencing of FAM20C and postnatal assessment. RESULTS The prenatal ultrasound findings of osteosclerotic skull, exorbitism, hypoplastic nose, midface hypoplasia, small mouth with down-curved corners, and a distinct and recognizable pattern of intracranial calcification were identified in three fetuses with RS. The calcifications were evident specifically around the corpus callosum and/or ventricular walls. Ectopic renal and hepatic calcifications, pulmonary hypoplasia, mild rhizomelic shortening of the upper limbs, intrauterine fractures, and cerebellar hypoplasia were also noted. Molecular analysis identified three novel homozygous variants, two frameshift: [c.456delC (p.Gly153Alafs*34)] in exon 1 and [c.905delT (Phe302Serfs*35)] in exon 4 and one nonsense mutation in exon 10, [c.1557C>G(p.Tyrs519*)]. The three variants were segregated with the phenotype. This is the first description of a phenotype associated with homozygous truncating variants of FAM20C. CONCLUSION RS has characteristic prenatal ultrasound findings which can improve the prenatal identification of this condition and help in guiding the molecular diagnosis and counseling.
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Affiliation(s)
- Sara H El-Dessouky
- Department of Prenatal Diagnosis & Fetal Medicine, Division of Human Genetics and Genome Research, National Research Centre, Cairo, Egypt
| | - Mohamed S Abdel-Hamid
- Department of Medical & Molecular Genetics, Division of Human Genetics and Genome Research, National Research Centre, Cairo, Egypt
| | - Sherif F Abdel-Ghafar
- Department of Medical & Molecular Genetics, Division of Human Genetics and Genome Research, National Research Centre, Cairo, Egypt
| | | | | | - Mona Fouad
- Fetal Medicine Unit, Cairo University, Cairo, Egypt
| | - Adel H Ahmed
- Fetal Medicine Unit, Cairo University, Cairo, Egypt
| | - Ghada M H Abdel-Salam
- Department of Clinical Genetics, Division of Human Genetics and Genome Research, National Research Centre, Cairo, Egypt
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Agoro R, Ni P, Noonan ML, White KE. Osteocytic FGF23 and Its Kidney Function. Front Endocrinol (Lausanne) 2020; 11:592. [PMID: 32982979 PMCID: PMC7485387 DOI: 10.3389/fendo.2020.00592] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/15/2020] [Accepted: 07/20/2020] [Indexed: 12/16/2022] Open
Abstract
Osteocytes, which represent up to 95% of adult skeletal cells, are deeply embedded in bone. These cells exhibit important interactive abilities with other bone cells such as osteoblasts and osteoclasts to control skeletal formation and resorption. Beyond this local role, osteocytes can also influence the function of distant organs due to the presence of their sophisticated lacunocanalicular system, which connects osteocyte dendrites directly to the vasculature. Through these networks, osteocytes sense changes in circulating metabolites and respond by producing endocrine factors to control homeostasis. One critical function of osteocytes is to respond to increased blood phosphate and 1,25(OH)2 vitamin D (1,25D) by producing fibroblast growth factor-23 (FGF23). FGF23 acts on the kidneys through partner fibroblast growth factor receptors (FGFRs) and the co-receptor Klotho to promote phosphaturia via a downregulation of phosphate transporters, as well as the control of vitamin D metabolizing enzymes to reduce blood 1,25D. In the first part of this review, we will explore the signals involved in the positive and negative regulation of FGF23 in osteocytes. In the second portion, we will bridge bone responses with the review of current knowledge on FGF23 endocrine functions in the kidneys.
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Affiliation(s)
- Rafiou Agoro
- Department of Medical and Molecular Genetics, Indiana University School of Medicine, Indianapolis, IN, United States
| | - Pu Ni
- Department of Medical and Molecular Genetics, Indiana University School of Medicine, Indianapolis, IN, United States
| | - Megan L. Noonan
- Department of Medical and Molecular Genetics, Indiana University School of Medicine, Indianapolis, IN, United States
| | - Kenneth E. White
- Department of Medical and Molecular Genetics, Indiana University School of Medicine, Indianapolis, IN, United States
- Medicine/Division of Nephrology, Indiana University School of Medicine, Indianapolis, IN, United States
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Eltan M, Alavanda C, Yavas Abali Z, Ergenekon P, Yalındag Ozturk N, Sakar M, Dagcinar A, Kirkgoz T, Kaygusuz SB, Gokdemir Y, Elcioglu HN, Guran T, Bereket A, Ata P, Turan S. A Rare Cause of Hypophosphatemia: Raine Syndrome Changing Clinical Features with Age. Calcif Tissue Int 2020; 107:96-103. [PMID: 32337609 PMCID: PMC7222149 DOI: 10.1007/s00223-020-00694-3] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/20/2019] [Accepted: 04/11/2020] [Indexed: 11/29/2022]
Abstract
Raine Syndrome (RS) is caused by biallelic loss-of-function mutations in FAM20C gene and characterized by hypophosphatemia, typical facial and skeletal features. Subperiosteal bone formation and generalized osteosclerosis are the most common radiological findings. Here we present a new case with RS. A 9-month-old male patient on a home-type ventilator was referred for hypophosphatemia. He was born with a weight of 3800 g to non-consanguineous parents. Prenatal ultrasound had demonstrated nasal bone agenesis. A large anterior fontanel, frontal bossing, exophthalmos, hypoplastic nose, high arched palate, low set ears, triangular mouth, and corneal opacification were detected on physical examination. Serial skeletal X-rays revealed diffuse osteosclerosis at birth which was gradually decreased by the age of 5 months with subperiosteal undermineralized bone formation and medullary space of long bone could be distinguishable with bone-within-a-bone appearance. At 9 months of age, hand X-ray revealed cupping of the ulna with loose radial bone margin with minimal fraying and osteopenia. Cranial computed tomography scan showed bilateral periventricular calcification and hydrocephalus in progress. The clinical, laboratory, and radiological examinations were consistent with RS. Molecular analyses revealed a compound heterozygous mutation in FAM20C gene (a known pathogenic mutation, c.1645C > T, p.Arg549Trp; and a novel c.863 + 5 G > C variant). The patient died due to respiratory failure at 17 months of age. This case allowed us to demonstrate natural progression of skeletal features in RS. Furthermore, we have described a novel FAM20C variant causing RS. Previous literature on RS is also reviewed.
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Affiliation(s)
- Mehmet Eltan
- Department of Pediatric Endocrinology and Diabetes, Marmara University School of Medicine, Istanbul, Turkey
| | - Ceren Alavanda
- Department of Medical Genetics, Marmara University School of Medicine, Istanbul, Turkey
| | - Zehra Yavas Abali
- Department of Pediatric Endocrinology and Diabetes, Marmara University School of Medicine, Istanbul, Turkey
| | - Pinar Ergenekon
- Department of Pediatric Chest Disease, Marmara University School of Medicine, Istanbul, Turkey
| | - Nilufer Yalındag Ozturk
- Department of Pediatric Intensive Care Unit, Marmara University School of Medicine, Istanbul, Turkey
| | - Mustafa Sakar
- Department of Pediatric Neurosurgery, Marmara University School of Medicine, Istanbul, Turkey
| | - Adnan Dagcinar
- Department of Pediatric Neurosurgery, Marmara University School of Medicine, Istanbul, Turkey
| | - Tarik Kirkgoz
- Department of Pediatric Endocrinology and Diabetes, Marmara University School of Medicine, Istanbul, Turkey
| | - Sare Betul Kaygusuz
- Department of Pediatric Endocrinology and Diabetes, Marmara University School of Medicine, Istanbul, Turkey
| | - Yasemin Gokdemir
- Department of Pediatric Chest Disease, Marmara University School of Medicine, Istanbul, Turkey
| | - Huriye Nursel Elcioglu
- Department of Pediatric Genetics, Marmara University School of Medicine, Istanbul, Turkey
| | - Tulay Guran
- Department of Pediatric Endocrinology and Diabetes, Marmara University School of Medicine, Istanbul, Turkey
| | - Abdullah Bereket
- Department of Pediatric Endocrinology and Diabetes, Marmara University School of Medicine, Istanbul, Turkey
| | - Pinar Ata
- Department of Medical Genetics, Marmara University School of Medicine, Istanbul, Turkey
| | - Serap Turan
- Department of Pediatric Endocrinology and Diabetes, Marmara University School of Medicine, Istanbul, Turkey.
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Cebeci AN, Zou M, BinEssa HA, Alzahrani AS, Al-Rijjal RA, Al-Enezi AF, Al-Mohanna FA, Cavalier E, Meyer BF, Shi Y. Mutation of SGK3, a Novel Regulator of Renal Phosphate Transport, Causes Autosomal Dominant Hypophosphatemic Rickets. J Clin Endocrinol Metab 2020; 105:5672651. [PMID: 31821448 DOI: 10.1210/clinem/dgz260] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/02/2019] [Accepted: 12/09/2019] [Indexed: 11/19/2022]
Abstract
CONTEXT Hypophosphatemic rickets (HR) is a group of rare hereditary renal phosphate wasting disorders caused by mutations in PHEX, FGF23, DMP1, ENPP1, CLCN5, SLC9A3R1, SLC34A1, or SLC34A3. OBJECTIVE A large kindred with 5 HR patients was recruited with dominant inheritance. The study was undertaken to investigate underlying genetic defects in HR patients. DESIGN Patients and their family members were initially analyzed for PHEX and FGF23 mutations using polymerase chain reaction sequencing and copy number analysis. Exome sequencing was subsequently performed to identify novel candidate genes. RESULTS PHEX and FGF23 mutations were not detected in the patients. No copy number variation was observed in the genome using CytoScan HD array analysis. Mutations in DMP1, ENPP1, CLCN5, SLC9A3R1, SLC34A1, or SLC34A3 were also not found by exome sequencing. A novel c.979-96 T>A mutation in the SGK3 gene was found to be strictly segregated in a heterozygous pattern in patients and was not present in normal family members. The mutation is located 1 bp downstream of a highly conserved adenosine branch point, resulted in exon 13 skipping and in-frame deletion of 29 amino acids, which is part of the protein kinase domain and contains a Thr-320 phosphorylation site that is required for its activation. Protein tertiary structure modelling showed significant structural change in the protein kinase domain following the deletion. CONCLUSIONS The c.979-96 T>A splice mutation in the SGK3 gene causes exon 13 skipping and deletion of 29 amino acids in the protein kinase domain. The SGK3 mutation may cause autosomal dominant HR.
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Affiliation(s)
- Ayşe Nurcan Cebeci
- Department of Pediatric Endocrinology, Istanbul Bilim University, Istanbul, Turkey
| | - Minjing Zou
- Department of Genetics, King Faisal Specialist Hospital & Research Centre, Riyadh, Saudi Arabia
| | - Huda A BinEssa
- Department of Genetics, King Faisal Specialist Hospital & Research Centre, Riyadh, Saudi Arabia
| | - Ali S Alzahrani
- Department of Medicine King Faisal Specialist Hospital & Research Centre, Riyadh, Saudi Arabia
| | - Roua A Al-Rijjal
- Department of Genetics, King Faisal Specialist Hospital & Research Centre, Riyadh, Saudi Arabia
| | - Anwar F Al-Enezi
- Department of Genetics, King Faisal Specialist Hospital & Research Centre, Riyadh, Saudi Arabia
| | - Futwan A Al-Mohanna
- Department of Cell Biology, King Faisal Specialist Hospital & Research Centre, Riyadh, Saudi Arabia
| | - Etienne Cavalier
- Department of Clinical Chemistry, University of Liège, CHU de Liège, Liège, Belgium
| | - Brian F Meyer
- Department of Genetics, King Faisal Specialist Hospital & Research Centre, Riyadh, Saudi Arabia
| | - Yufei Shi
- Department of Genetics, King Faisal Specialist Hospital & Research Centre, Riyadh, Saudi Arabia
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Zhang H, Li L, Kesterke MJ, Lu Y, Qin C. High-Phosphate Diet Improved the Skeletal Development of Fam20c-Deficient Mice. Cells Tissues Organs 2020; 208:25-36. [PMID: 32101876 DOI: 10.1159/000506005] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2019] [Accepted: 01/19/2020] [Indexed: 12/29/2022] Open
Abstract
FAM20C (family with sequence similarity 20 - member C) is a protein kinase that phosphorylates secretory proteins, including the proteins that are essential to the formation and mineralization of calcified tissues. Previously, we reported that inactivation of Fam20c in mice led to hypophosphatemic rickets/osteomalacia along with increased circulating fibroblast growth factor 23 (FGF23) levels and dental defects. In this study, we examined whether a high-phosphate (hPi) diet could rescue the skeletal defects in Fam20c-deficient mice. Fam20c conditional knockout (cKO) mice were generated by crossing female Fam20c-floxed mice (Fam20cfl/fl) with male Sox2-Cre;Fam20cfl/+ mice. The pregnant female Fam20cfi/fl mice were fed either a normal or hPi diet until the litters were weaned. The cKO and control offspring were continuously given a normal or hPi diet for 4 weeks after weaning. Plain X-ray radiography, micro-CT, histology, immunohistochemistry (FGF23, DMP1, OPN, and SOX9), and in situ hybridization (type II and type X collagen) analyses were performed to evaluate the effects of an hPi diet on the mouse skeleton. Plain X-ray radiography and micro-CT radiography analyses showed that the hPi diet improved the shape and mineral density of the Fam20c-deficient femurs/tibiae, and rescued the growth plate defects in the long bone. Histology analyses further demonstrated that an hPi diet nearly completely rescued the growth plate-widening defects in the long bone and restored the expanded hypertrophic zone to nearly normal width. These results suggested that the hPi diet significantly improved the skeletal development of the Fam20c-deficient mice, implying that hypophosphatemia partially contributed to the skeletal defects in Fam20c-deficient subjects.
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Affiliation(s)
- Hua Zhang
- Department of Biomedical Sciences, Texas A&M University College of Dentistry, Dallas, Texas, USA,
| | - Lili Li
- Department of Biomedical Sciences, Texas A&M University College of Dentistry, Dallas, Texas, USA
| | - Matthew J Kesterke
- Department of Biomedical Sciences, Texas A&M University College of Dentistry, Dallas, Texas, USA
| | - Yongbo Lu
- Department of Biomedical Sciences, Texas A&M University College of Dentistry, Dallas, Texas, USA
| | - Chunlin Qin
- Department of Biomedical Sciences, Texas A&M University College of Dentistry, Dallas, Texas, USA
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Hernández-Zavala A, Cortés-Camacho F, Palma-Lara I, Godínez-Aguilar R, Espinosa AM, Pérez-Durán J, Villanueva-Ocampo P, Ugarte-Briones C, Serrano-Bello CA, Sánchez-Santiago PJ, Bonilla-Delgado J, Yáñez-López MA, Victoria-Acosta G, López-Ornelas A, García Alonso-Themann P, Moreno J, Palacios-Reyes C. Two Novel FAM20C Variants in A Family with Raine Syndrome. Genes (Basel) 2020; 11:genes11020222. [PMID: 32093234 PMCID: PMC7073523 DOI: 10.3390/genes11020222] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2019] [Revised: 01/30/2020] [Accepted: 02/14/2020] [Indexed: 12/14/2022] Open
Abstract
Two siblings from a Mexican family who carried lethal Raine syndrome are presented. A newborn term male (case 1) and his 21 gestational week brother (case 2), with a similar osteosclerotic pattern: generalized osteosclerosis, which is more evident in facial bones and cranial base. Prenatal findings at 21 weeks and histopathological features for case 2 are described. A novel combination of biallelic FAM20C pathogenic variants were detected, a maternal cytosine duplication at position 456 and a paternal deletion of a cytosine in position 474 in exon 1, which change the reading frame with a premature termination at codon 207 and 185 respectively. These changes are in concordance with a negative detection of the protein in liver and kidney as shown in case 2. Necropsy showed absence of pancreatic Langerhans Islets, which are reported here for the first time. Corpus callosum absence is added to the few reported cases of brain defects in Raine syndrome. This report shows two new FAM20C variants not described previously, and negative protein detection in the liver and the kidney. We highlight that lethal Raine syndrome is well defined as early as 21 weeks, including mineralization defects and craniofacial features. Pancreas and brain defects found here in FAM20C deficiency extend the functional spectrum of this protein to previously unknown organs.
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Affiliation(s)
- Araceli Hernández-Zavala
- Laboratory of Cellular and Molecular Morphology, Section of Postgraduate Studies and Research, Escuela Superior de Medicina, Instituto Politécnico Nacional, Salvador Díaz Mirón esq. Plan de San Luis S/N, Miguel Hidalgo, Casco de Santo Tomas, Mexico City 11340, Mexico; (A.H.-Z.); (F.C.-C.); (I.P.-L.)
| | - Fernando Cortés-Camacho
- Laboratory of Cellular and Molecular Morphology, Section of Postgraduate Studies and Research, Escuela Superior de Medicina, Instituto Politécnico Nacional, Salvador Díaz Mirón esq. Plan de San Luis S/N, Miguel Hidalgo, Casco de Santo Tomas, Mexico City 11340, Mexico; (A.H.-Z.); (F.C.-C.); (I.P.-L.)
- Direction and Division of Research, Hospital Juárez de México, Av. Instituto Politécnico Nacional 5160, Magdalena de las Salinas, Gustavo A. Madero, Mexico City 07760, Mexico; (R.G.-A.); (J.B.-D.); (G.V.-A.); (A.L.-O.); (J.M.)
| | - Icela Palma-Lara
- Laboratory of Cellular and Molecular Morphology, Section of Postgraduate Studies and Research, Escuela Superior de Medicina, Instituto Politécnico Nacional, Salvador Díaz Mirón esq. Plan de San Luis S/N, Miguel Hidalgo, Casco de Santo Tomas, Mexico City 11340, Mexico; (A.H.-Z.); (F.C.-C.); (I.P.-L.)
| | - Ricardo Godínez-Aguilar
- Direction and Division of Research, Hospital Juárez de México, Av. Instituto Politécnico Nacional 5160, Magdalena de las Salinas, Gustavo A. Madero, Mexico City 07760, Mexico; (R.G.-A.); (J.B.-D.); (G.V.-A.); (A.L.-O.); (J.M.)
| | - Ana María Espinosa
- Service of Clinical Pharmacology, Hospital General de México, Dr. Balmis 148, Doctores, Cuauhtémoc, Mexico City 06720, Mexico;
| | - Javier Pérez-Durán
- National Institute of Perinatology, Calle Montes Urales 800, Lomas - Virreyes, Lomas de Chapultepec IV Section, Miguel Hidalgo, Mexico City 11000, Mexico; (J.P.-D.); (P.G.A.-T.)
| | - Patricia Villanueva-Ocampo
- Deparment of Ginecology, Hospital Juárez de México, Av. Instituto Politécnico Nacional 5160, Magdalena de las Salinas, Gustavo A. Madero, Mexico City 07760, Mexico;
| | - Carlos Ugarte-Briones
- Department of Pathology, Hospital Juárez de México, Av. Instituto Politécnico Nacional 5160, Magdalena de las Salinas, Gustavo A. Madero, Mexico City 07760, Mexico; (C.U.-B.); (C.A.S.-B.); (P.J.S.-S.)
| | - Carlos Alberto Serrano-Bello
- Department of Pathology, Hospital Juárez de México, Av. Instituto Politécnico Nacional 5160, Magdalena de las Salinas, Gustavo A. Madero, Mexico City 07760, Mexico; (C.U.-B.); (C.A.S.-B.); (P.J.S.-S.)
| | - Paula Jesús Sánchez-Santiago
- Department of Pathology, Hospital Juárez de México, Av. Instituto Politécnico Nacional 5160, Magdalena de las Salinas, Gustavo A. Madero, Mexico City 07760, Mexico; (C.U.-B.); (C.A.S.-B.); (P.J.S.-S.)
| | - José Bonilla-Delgado
- Direction and Division of Research, Hospital Juárez de México, Av. Instituto Politécnico Nacional 5160, Magdalena de las Salinas, Gustavo A. Madero, Mexico City 07760, Mexico; (R.G.-A.); (J.B.-D.); (G.V.-A.); (A.L.-O.); (J.M.)
| | - Marco Antonio Yáñez-López
- Department of Radiology & Imagenology, Hospital Juárez de México, Av. Instituto Politécnico Nacional 5160, Magdalena de las Salinas, Gustavo A. Madero, Mexico City 07760, Mexico;
| | - Georgina Victoria-Acosta
- Direction and Division of Research, Hospital Juárez de México, Av. Instituto Politécnico Nacional 5160, Magdalena de las Salinas, Gustavo A. Madero, Mexico City 07760, Mexico; (R.G.-A.); (J.B.-D.); (G.V.-A.); (A.L.-O.); (J.M.)
| | - Adolfo López-Ornelas
- Direction and Division of Research, Hospital Juárez de México, Av. Instituto Politécnico Nacional 5160, Magdalena de las Salinas, Gustavo A. Madero, Mexico City 07760, Mexico; (R.G.-A.); (J.B.-D.); (G.V.-A.); (A.L.-O.); (J.M.)
| | - Patricia García Alonso-Themann
- National Institute of Perinatology, Calle Montes Urales 800, Lomas - Virreyes, Lomas de Chapultepec IV Section, Miguel Hidalgo, Mexico City 11000, Mexico; (J.P.-D.); (P.G.A.-T.)
| | - José Moreno
- Direction and Division of Research, Hospital Juárez de México, Av. Instituto Politécnico Nacional 5160, Magdalena de las Salinas, Gustavo A. Madero, Mexico City 07760, Mexico; (R.G.-A.); (J.B.-D.); (G.V.-A.); (A.L.-O.); (J.M.)
| | - Carmen Palacios-Reyes
- Direction and Division of Research, Hospital Juárez de México, Av. Instituto Politécnico Nacional 5160, Magdalena de las Salinas, Gustavo A. Madero, Mexico City 07760, Mexico; (R.G.-A.); (J.B.-D.); (G.V.-A.); (A.L.-O.); (J.M.)
- Correspondence:
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Saraff V, Nadar R, Högler W. New Developments in the Treatment of X-Linked Hypophosphataemia: Implications for Clinical Management. Paediatr Drugs 2020; 22:113-121. [PMID: 31965544 PMCID: PMC7083817 DOI: 10.1007/s40272-020-00381-8] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
X-linked hypophosphataemia (XLH) is due to mutations in phosphate-regulating gene with homologies to endopeptidases on the X chromosome (PHEX) and represents the most common heritable form of rickets. In this condition, the hormone fibroblast growth factor 23 (FGF23) is produced in excessive amounts for still unknown reasons, and causes renal phosphate wasting and suppression of 1,25-dihydroxyvitamin D, leading to low serum phosphate concentrations. Prolonged hypophosphataemia decreases apoptosis of hypertrophic chondrocytes in growth plates (causing rickets) and decreases mineralisation of existing bone (causing osteomalacia). In contrast to historical conventional treatment with oral phosphate supplements and active vitamin D for the last 50 years, the new anti-FGF23 antibody treatment (burosumab) targets the primary pathology by blocking FGF23, thereby restoring phosphate homeostasis. In this review, we describe the changes in treatment monitoring, treatment targets and long-term treatment goals, including future opportunities and challenges in the treatment of XLH in children.
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Affiliation(s)
- Vrinda Saraff
- Department of Endocrinology and Diabetes, Birmingham Women’s and Children’s Hospital NHS Trust, Birmingham, UK ,grid.6572.60000 0004 1936 7486Institute of Applied Health Research, University of Birmingham, Birmingham, UK
| | - Ruchi Nadar
- Department of Endocrinology and Diabetes, Birmingham Women’s and Children’s Hospital NHS Trust, Birmingham, UK
| | - Wolfgang Högler
- Institute of Metabolism and Systems Research, University of Birmingham, Birmingham, UK. .,Department of Pediatrics and Adolescent Medicine, Johannes Kepler University Linz, Kepler Universitätsklinikum, Krankenhausstrasse 26-30, 4020, Linz, Austria.
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Michigami T. Skeletal mineralization: mechanisms and diseases. Ann Pediatr Endocrinol Metab 2019; 24:213-219. [PMID: 31905439 PMCID: PMC6944863 DOI: 10.6065/apem.2019.24.4.213] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/30/2019] [Accepted: 12/20/2019] [Indexed: 12/22/2022] Open
Abstract
Skeletal mineralization is initiated in matrix vesicles (MVs), the small extracellular vesicles derived from osteoblasts and chondrocytes. Calcium and inorganic phosphate (Pi) taken up by MVs form hydroxyapatite crystals, which propagate on collagen fibrils to mineralize the extracellular matrix. Insufficient calcium or phosphate impairs skeletal mineralization. Because active vitamin D is necessary for intestinal calcium absorption, vitamin D deficiency is a significant cause of rickets/osteomalacia. Chronic hypophosphatemia also results in rickets/osteomalacia. Excessive action of fibroblast growth factor 23 (FGF23), a key regulator of Pi metabolism, leads to renal Pi wasting and impairs vitamin D activation. X-linked hypophosphatemic rickets (XLH) is the most common form of hereditary FGF23-related hypophosphatemia, and enhanced FGF receptor (FGFR) signaling in osteocytes may be involved in the pathogenesis of this disease. Increased extracellular Pi triggers signal transduction via FGFR to regulate gene expression, implying a close relationship between Pi metabolism and FGFR. An anti-FGF23 antibody, burosumab, has recently been developed as a new treatment for XLH. In addition to various forms of rickets/osteomalacia, hypophosphatasia (HPP) is characterized by impaired skeletal mineralization. HPP is caused by inactivating mutations in tissue-nonspecific alkaline phosphatase, an enzyme rich in MVs. The recent development of enzyme replacement therapy using bone-targeting recombinant alkaline phosphatase has improved the prognosis, motor function, and quality of life in patients with HPP. This links impaired skeletal mineralization with various conditions, and unraveling its pathogenesis will lead to more precise diagnoses and effective treatments.
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Affiliation(s)
- Toshimi Michigami
- Department of Bone and Mineral Research, Research Institute, Osaka Women’s and Children’s Hospital, Osaka Prefectural Hospital Organization, Izumi, Japan,Address for correspondence: Toshimi Michigami, MD, PhD Department of Bone and Mineral Research, Research I nstitute, Osaka Women’s and Children’s Hospital, Osaka Prefectural Hospital Organization, 840 Murodo-cho, Izumi, Osaka 594-1101, Japan Tel: +81-725-56-1220 Fax: +81-725-57-3021 E-mail:
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Mamedova E, Dimitrova D, Przhiyalkovskaya E, Buryakina S, Vasilyev E, Tiulpakov A, Belaya Z. Non-lethal Raine Syndrome in a Middle-Aged Woman Caused by a Novel FAM20C Mutation. Calcif Tissue Int 2019; 105:567-572. [PMID: 31471673 DOI: 10.1007/s00223-019-00599-w] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/21/2019] [Accepted: 08/16/2019] [Indexed: 12/21/2022]
Abstract
Raine syndrome is a rare hereditary disease caused by mutations in the FAM20C gene. Only 18 non-lethal cases have been reported, the majority of them being children and young adults aged up to 30. Due to the rarity of the disease, genotype-phenotype correlations are not available and patient life expectancy is unknown, thus making descriptions of each novel case of particular importance. In this article, we describe a case of an Armenian woman, living in Russia, who was followed-up from age 36 to 39, presenting with pain in the extremities, osteosclerosis with periosteal bone formation, multiple calcifications in solid organs, midface hypoplasia, exophthalmos, amelogenesis imperfecta, shortening of distal phalanges, pectus excavatum, and hypophosphatemia due to renal phosphate wasting. Whole exome sequencing was performed on NextSeq 550 (Illumina, USA) and compound heterozygous variants were identified in the FAM20C gene (reference sequence NM_020223): a frameshift insertion c.1107_1108insTACTG (p.Tyr369fs) and a missense substitution c.1375C > G (p.Arg459Gly). This is the first reported case of a middle-aged patient presenting classical symptoms of Raine syndrome caused by novel compound heterozygous mutations in the conserved C-terminal domain of FAM20C gene.
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Affiliation(s)
- Elizaveta Mamedova
- Department of Neuroendocrinology and Bone Diseases, Endocrinology Research Centre, Ulitsa Dmitriya Ulianova, 11, Moscow, 117036, Russian Federation.
| | - Diana Dimitrova
- Department of Neuroendocrinology and Bone Diseases, Endocrinology Research Centre, Ulitsa Dmitriya Ulianova, 11, Moscow, 117036, Russian Federation
| | - Elena Przhiyalkovskaya
- Department of Neuroendocrinology and Bone Diseases, Endocrinology Research Centre, Ulitsa Dmitriya Ulianova, 11, Moscow, 117036, Russian Federation
| | - Svetlana Buryakina
- Department of Radiology, Endocrinology Research Centre, Ulitsa Dmitriya Ulianova, 11, Moscow, 117036, Russian Federation
| | - Evgeny Vasilyev
- Department and Laboratory of Inherited Endocrine Disorders, Endocrinology Research Centre, Ulitsa Dmitriya Ulianova, 11, Moscow, 117036, Russian Federation
| | - Anatoly Tiulpakov
- Department and Laboratory of Inherited Endocrine Disorders, Endocrinology Research Centre, Ulitsa Dmitriya Ulianova, 11, Moscow, 117036, Russian Federation
| | - Zhanna Belaya
- Department of Neuroendocrinology and Bone Diseases, Endocrinology Research Centre, Ulitsa Dmitriya Ulianova, 11, Moscow, 117036, Russian Federation
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FGF23 at the crossroads of phosphate, iron economy and erythropoiesis. Nat Rev Nephrol 2019; 16:7-19. [PMID: 31519999 DOI: 10.1038/s41581-019-0189-5] [Citation(s) in RCA: 154] [Impact Index Per Article: 30.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/24/2019] [Indexed: 12/20/2022]
Abstract
Fibroblast growth factor 23 (FGF23) was initially characterized as an important regulator of phosphate and calcium homeostasis. New research advances demonstrate that FGF23 is also linked to iron economy, inflammation and erythropoiesis. These advances have been fuelled, in part, by the serendipitous development of two distinct FGF23 assays that can substitute for invasive bone biopsies to infer the activity of the three main steps of FGF23 regulation in bone: transcription, post-translational modification and peptide cleavage. This 'liquid bone biopsy for FGF23 dynamics' enables large-scale longitudinal studies of FGF23 regulation that would otherwise be impossible in humans. The balance between FGF23 production, post-translational modification and cleavage is maintained or perturbed in different hereditary monogenic conditions and in acquired conditions that mimic these genetic disorders, including iron deficiency, inflammation, treatment with ferric carboxymaltose and chronic kidney disease. Looking ahead, a deeper understanding of the relationships between FGF23 regulation, iron homeostasis and erythropoiesis can be leveraged to devise novel therapeutic targets for treatment of anaemia and states of FGF23 excess, including chronic kidney disease.
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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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Imel EA, Biggin A, Schindeler A, Munns CF. FGF23, Hypophosphatemia, and Emerging Treatments. JBMR Plus 2019; 3:e10190. [PMID: 31485552 PMCID: PMC6715782 DOI: 10.1002/jbm4.10190] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/29/2018] [Revised: 02/13/2019] [Accepted: 02/26/2019] [Indexed: 01/03/2023] Open
Abstract
FGF23 is an important hormonal regulator of phosphate homeostasis. Together with its co-receptor Klotho, it modulates phosphate reabsorption and both 1α-hydroxylation and 24-hydroxylation in the renal proximal tubules. The most common FGF23-mediated hypophosphatemia is X-linked hypophosphatemia (XLH), caused by mutations in the PHEX gene. FGF23-mediated forms of hypophosphatemia are characterized by phosphaturia and low or low-normal calcitriol concentrations, and unlike nutritional rickets, these cannot be cured with nutritional vitamin D supplementation. Autosomal dominant and autosomal recessive forms of FGF23-mediated hypophosphatemias show a similar pathophysiology, despite a variety of different underlying genetic causes. An excess of FGF23 activity has also been associated with a number of other conditions causing hypophosphatemia, including tumor-induced osteomalacia, fibrous dysplasia of the bone, and cutaneous skeletal hypophosphatemia syndrome. Historically phosphate supplementation and therapy using analogs of highly active vitamin D (eg, calcitriol, alfacalcidol, paricalcitol, eldecalcitol) have been used to manage conditions involving hypophosphatemia; however, recently a neutralizing antibody for FGF23 (burosumab) has emerged as a promising treatment agent for FGF23-mediated disorders. This review discusses the progression of clinical trials for burosumab for the treatment of XLH and its recent availability for clinical use. Burosumab may have potential for treating other conditions associated with FGF23 overactivity, but these are not yet supported by trial data. © 2019 The Authors. JBMR Plus published by Wiley Periodicals, Inc. on behalf of American Society for Bone and Mineral Research.
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Affiliation(s)
- Erik A Imel
- Division of EndocrinologyIndiana University School of Medicine, Indianapolis, INUSA
| | - Andrew Biggin
- The University of Sydney Children's Hospital Westmead Clinical School, University of SydneySydneyAustralia
- Department of EndocrinologyThe Children's Hospital at WestmeadWestmeadAustralia
| | - Aaron Schindeler
- The University of Sydney Children's Hospital Westmead Clinical School, University of SydneySydneyAustralia
- Orthopaedic Research Unit, The Children's Hospital at WestmeadWestmeadAustralia
| | - Craig F Munns
- The University of Sydney Children's Hospital Westmead Clinical School, University of SydneySydneyAustralia
- Department of EndocrinologyThe Children's Hospital at WestmeadWestmeadAustralia
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Hung CY, Rodriguez M, Roberts A, Bauer M, Mihalek I, Bodamer O. A novel FAM20C mutation causes a rare form of neonatal lethal Raine syndrome. Am J Med Genet A 2019; 179:1866-1871. [PMID: 31297960 DOI: 10.1002/ajmg.a.61291] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2019] [Revised: 05/08/2019] [Accepted: 06/23/2019] [Indexed: 02/06/2023]
Abstract
Raine syndrome is a rare, autosomal recessive, osteosclerotic bone dysplasia due to pathogenic variants in FAM20C. The clinical phenotype is characterized by generalized osteosclerosis affecting all bones, cerebral calcifications, and craniofacial dysmorphism. Most cases present during the neonatal period with early lethality due to pulmonary hypoplasia and respiratory compromise while only few affected individuals have been reported to survive into adulthood. FAM20C is a ubiquitously expressed protein kinase that contains five functional domains including a catalytic domain, a binding pocket for FAM20A and three distinct N-glycosylation sites. We report a newborn infant with a history of prenatal onset fractures, generalized osteosclerosis, and craniofacial dysmorphism and early lethality. The clinical presentation was highly suggestive of Raine syndrome. A homozygous, novel missense variant in exon 5 of FAM20C (c.1007T>G; p.Met336Arg) was identified by targeted Sanger sequencing. Following in silico analysis and mapping of the variant on a three-dimensional (3D) model of FAM20C it is predicted to be deleterious and to affect N-glycosylation, protein folding, and subsequent secretion of FAM20C. In addition, we reviewed all published FAM20C mutations and observed that most pathogenic variants affect functional regions within the protein establishing evidence for an emerging genotype-phenotype correlation.
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Affiliation(s)
- Christina Y Hung
- Division of Genetics and Genomics, Boston Children's Hospital, Boston, Massachusetts
| | - Mario Rodriguez
- Hussmann Institute of Genomics, University of Miami, Miami, Florida
| | - Abra Roberts
- Division of Genetics and Genomics, Boston Children's Hospital, Boston, Massachusetts
| | - Mislen Bauer
- Division of Clinical Genetics and Metabolism, Nicklas Children's Hospital, Miami, Florida
| | - Ivana Mihalek
- Department of Molecular Medicine and Biotechnology, University of Rijeka, Rijeka, Croatia
| | - Olaf Bodamer
- Division of Genetics and Genomics, Boston Children's Hospital, Boston, Massachusetts
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Bär L, Stournaras C, Lang F, Föller M. Regulation of fibroblast growth factor 23 (FGF23) in health and disease. FEBS Lett 2019; 593:1879-1900. [PMID: 31199502 DOI: 10.1002/1873-3468.13494] [Citation(s) in RCA: 52] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2019] [Revised: 03/26/2019] [Accepted: 03/27/2019] [Indexed: 12/19/2022]
Abstract
Fibroblast growth factor 23 (FGF23) is mainly produced in the bone and, upon secretion, forms a complex with a FGF receptor and coreceptor αKlotho. FGF23 can exert several endocrine functions, such as inhibiting renal phosphate reabsorption and 1,25-dihydroxyvitamin D3 production. Moreover, it has paracrine activities on several cell types, including neutrophils and hepatocytes. Klotho and Fgf23 deficiencies result in pathologies otherwise encountered in age-associated diseases, mainly as a result of hyperphosphataemia-dependent calcification. FGF23 levels are also perturbed in the plasma of patients with several disorders, including kidney or cardiovascular diseases. Here, we review mechanisms controlling FGF23 production and discuss how FGF23 regulation is perturbed in disease.
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Affiliation(s)
- Ludmilla Bär
- Institute of Agricultural and Nutritional Sciences, Martin Luther University Halle-Wittenberg, Halle (Saale), Germany
| | - Christos Stournaras
- Institute of Biochemistry, University of Crete Medical School, Heraklion, Greece
| | - Florian Lang
- Institute of Physiology, University of Tübingen, Germany
| | - Michael Föller
- Institute of Physiology, University of Hohenheim, Stuttgart, Germany
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48
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Park BC, Reese M, Tagliabracci VS. Thinking outside of the cell: Secreted protein kinases in bacteria, parasites, and mammals. IUBMB Life 2019; 71:749-759. [PMID: 30941842 DOI: 10.1002/iub.2040] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2018] [Revised: 03/05/2019] [Accepted: 03/13/2019] [Indexed: 01/02/2023]
Abstract
Previous decades have seen an explosion in our understanding of protein kinase function in human health and disease. Hundreds of unique kinase structures have been solved, allowing us to create generalized rules for catalysis, assign roles of communities within the catalytic core, and develop specific drugs for targeting various pathways. Although our understanding of intracellular kinases has developed at a fast rate, our exploration into extracellular kinases has just begun. In this review, we will cover the secreted protein kinase families found in humans, bacteria, and parasites. © 2019 IUBMB Life, 71(6):749-759, 2019.
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Affiliation(s)
- Brenden C Park
- Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Michael Reese
- Department of Pharmacology, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Vincent S Tagliabracci
- Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, TX, USA.,Harold C. Simmons Comprehensive Cancer Center, University of Texas Southwestern Medical Center, Dallas, TX, USA.,Hamon Center for Regenerative Science and Medicine, University of Texas Southwestern Medical Center, Dallas, TX, USA
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49
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Hum JM, O'Bryan LM, Tatiparthi AK, Clinkenbeard EL, Ni P, Cramer MS, Bhaskaran M, Johnson RL, Wilson JM, Smith RC, White KE. Sustained Klotho delivery reduces serum phosphate in a model of diabetic nephropathy. J Appl Physiol (1985) 2019; 126:854-862. [PMID: 30605400 PMCID: PMC6485689 DOI: 10.1152/japplphysiol.00838.2018] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2018] [Revised: 12/12/2018] [Accepted: 12/29/2018] [Indexed: 12/26/2022] Open
Abstract
Diabetic nephropathy (DN) is a primary cause of end-stage renal disease and is becoming more prevalent because of the global rise in type 2 diabetes. A model of DN, the db/db uninephrectomized ( db/db-uni) mouse, is characterized by obesity, as well as compromised renal function. This model also manifests defects in mineral metabolism common in DN, including hyperphosphatemia, which leads to severe endocrine disease. The FGF23 coreceptor, α-Klotho, circulates as a soluble, cleaved form (cKL) and may directly influence phosphate handling. Our study sought to test the effects of cKL on mineral metabolism in db/db-uni mice. Mice were placed into either mild or moderate disease groups on the basis of the albumin-to-creatinine ratio (ACR). Body weights of db/db-uni mice were significantly greater across the study compared with lean controls regardless of disease severity. Adeno-associated cKL administration was associated with increased serum Klotho, intact, bioactive FGF23 (iFGF23), and COOH-terminal fragments of FGF23 ( P < 0.05). Blood urea nitrogen was improved after cKL administration, and cKL corrected hyperphosphatemia in the high- and low-ACR db/db-uni groups. Interestingly, 2 wk after cKL delivery, blood glucose levels were significantly reduced in db/db-uni mice with high ACR ( P < 0.05). Interestingly, several genes associated with stabilizing active iFGF23 were also increased in the osteoblastic UMR-106 cell line with cKL treatment. In summary, delivery of cKL to a model of DN normalized blood phosphate levels regardless of disease severity, supporting the concept that targeting cKL-affected pathways could provide future therapeutic avenues in DN. NEW & NOTEWORTHY In this work, systemic and continuous delivery of the "soluble" or "cleaved" form of the FGF23 coreceptor α-Klotho (cKL) via adeno-associated virus to a rodent model of diabetic nephropathy (DN), the db/db uninephrectomized mouse, normalized blood phosphate levels regardless of disease severity. This work supports the concept that targeting cKL-affected pathways could provide future therapeutic avenues for the severe mineral metabolism defects associated with DN.
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Affiliation(s)
- Julia M Hum
- Division of Molecular Genetics and Gene Therapy, Department of Medical and Molecular Genetics, Indiana University School of Medicine , Indianapolis, Indiana
- Division of Biomedical Sciences, College of Osteopathic Medicine, Marian University , Indianapolis, Indiana
| | - Linda M O'Bryan
- Biotechnology Discovery Research, Lilly Research Laboratories, Eli Lilly and Company , Indianapolis, Indiana
| | - Arun K Tatiparthi
- Lead Optimization Toxicology and Pharmacology, Covance Incorporated, Greenfield, Indiana
| | - Erica L Clinkenbeard
- Division of Molecular Genetics and Gene Therapy, Department of Medical and Molecular Genetics, Indiana University School of Medicine , Indianapolis, Indiana
| | - Pu Ni
- Division of Molecular Genetics and Gene Therapy, Department of Medical and Molecular Genetics, Indiana University School of Medicine , Indianapolis, Indiana
| | - Martin S Cramer
- Biotechnology Discovery Research, Lilly Research Laboratories, Eli Lilly and Company , Indianapolis, Indiana
| | - Manoj Bhaskaran
- Toxicology and Pathology, Eli Lilly and Company , Indianapolis, Indiana
| | - Robert L Johnson
- Toxicology and Pathology, Eli Lilly and Company , Indianapolis, Indiana
| | - Jonathan M Wilson
- Tailored Therapeutics, Eli Lilly and Company , Indianapolis, Indiana
| | - Rosamund C Smith
- Biotechnology Discovery Research, Lilly Research Laboratories, Eli Lilly and Company , Indianapolis, Indiana
| | - Kenneth E White
- Division of Molecular Genetics and Gene Therapy, Department of Medical and Molecular Genetics, Indiana University School of Medicine , Indianapolis, Indiana
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50
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Rolvien T, Kornak U, Schinke T, Amling M, Oheim R. A novel FAM20C mutation causing hypophosphatemic osteomalacia with osteosclerosis (mild Raine syndrome) in an elderly man with spontaneous osteonecrosis of the knee. Osteoporos Int 2019; 30:685-689. [PMID: 30151622 DOI: 10.1007/s00198-018-4667-6] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/13/2018] [Accepted: 08/12/2018] [Indexed: 12/11/2022]
Abstract
Raine syndrome is characterized by FGF23-mediated hypophosphatemic osteomalacia with osteosclerosis caused by mutations in the FAM20C gene. We report a case of a 72-year-old man who presented with rapid progressive spontaneous osteonecrosis of the knee (SONK). A full osteologic assessment including dual energy X-ray absorptiometry (DXA), high-resolution peripheral quantitative computed tomography (HR-pQCT), and serum analyses revealed a high bone mass in the lumbar spine and hip (DXA T-score + 7.5 and + 4.7/+4.2) with increased bone microstructural parameters in the distal radius and tibia (BV/TV 127%, 140% of the age-matched mean, respectively), as well as a low bone turnover state. Phosphate levels were low due to renal phosphate wasting and high FGF23 levels (126.5 pg/ml, reference range 23.2-95.4 pg/ml). Using gene panel sequencing, we identified a novel FAM20C heterozygous missense mutation in combination with a homozygous duplication that potentially alters splicing. Taken together, this is the first case of mild Raine syndrome with spontaneous osteonecrosis of the knee, phosphate wasting, and a pronounced trabecular high bone mass phenotype.
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Affiliation(s)
- T Rolvien
- Department of Osteology and Biomechanics, University Medical Center Hamburg-Eppendorf, Lottestr. 59, 22529, Hamburg, Germany
- Department of Orthopedics, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
- National Bone Board, Martin Zeitz Center for Rare Diseases, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - U Kornak
- National Bone Board, Martin Zeitz Center for Rare Diseases, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
- Institute of Medical Genetics and Human Genetics, Charité-Universitätsmedizin Berlin, Berlin, Germany
- Berlin-Brandenburg School for Regenerative Therapies, Charité-Universitätsmedizin Berlin, Berlin, Germany
- FG Development and Disease, Max Planck Institute for Molecular Genetics, Berlin, Germany
| | - T Schinke
- Department of Osteology and Biomechanics, University Medical Center Hamburg-Eppendorf, Lottestr. 59, 22529, Hamburg, Germany
- National Bone Board, Martin Zeitz Center for Rare Diseases, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - M Amling
- Department of Osteology and Biomechanics, University Medical Center Hamburg-Eppendorf, Lottestr. 59, 22529, Hamburg, Germany
- National Bone Board, Martin Zeitz Center for Rare Diseases, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - R Oheim
- Department of Osteology and Biomechanics, University Medical Center Hamburg-Eppendorf, Lottestr. 59, 22529, Hamburg, Germany.
- National Bone Board, Martin Zeitz Center for Rare Diseases, University Medical Center Hamburg-Eppendorf, Hamburg, Germany.
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