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De Mattia G, Maffi M, Mosca M, Mazzantini M. LRP5 high bone mass (Worth-type autosomal dominant endosteal hyperostosis): case report and historical review of the literature. Arch Osteoporos 2023; 18:112. [PMID: 37659026 PMCID: PMC10474981 DOI: 10.1007/s11657-023-01319-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/10/2023] [Accepted: 08/07/2023] [Indexed: 09/05/2023]
Abstract
PURPOSE LRP5 high bone mass (HBM) is an autosomal dominant endosteal hyperostosis caused by mutations of the low-density lipoprotein receptor-related protein 5 (LRP5) gene. Alternative names included "autosomal dominant osteosclerosis" and "Worth disease." The aim of the paper is to provide an historical overview of a disorder whose literature is complicated and confusing due to the past use of several denominations and lack of reviews. METHODS We collected case reports of HBM with evidence of autosomal dominant transmission preceding the identification of the LRP5 mutations in 2002 (Worth-type endosteal hyperostosis) and cases of LRP5 HBM confirmed by genetic analysis since 2002. The prevalence of relevant clinical and laboratory findings was estimated. We described an affected woman with neurological manifestations. RESULTS A 44-year-old Caucasian woman with torus palatinus complained of headache, hypo-/anosmia, and complete mixed deafness. Dual-energy X-ray absorptiometry (DEXA) scan revealed elevated bone mass. The A242T mutation of the LRP5 gene was detected. Including the present case, 155 patients have been reported to date. Neurological involvement and increased serum alkaline phosphatase (ALP) were present in 19.4% and 3.7% of cases, respectively. Facial changes and torus palatinus were observed in 61% and 41% of cases, respectively. CONCLUSIONS We present the only historical review on Worth-type endosteal hyperostosis, now known as LRP5 HBM. Neurological manifestations, previously considered absent in the disease, affect 19.4% of the patients. Genetic analysis and appropriate denomination of LRP5 HBM are fundamental for diagnosis and to mitigate the confusion that has long characterized this disease.
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Affiliation(s)
- Giammarco De Mattia
- Rare Bone Diseases Clinic, Rheumatology Unit, Department of Clinical and Experimental Medicine, University of Pisa, Pisa, Italy.
| | - Michele Maffi
- Rare Bone Diseases Clinic, Rheumatology Unit, Department of Clinical and Experimental Medicine, University of Pisa, Pisa, Italy
| | - Marta Mosca
- Rheumatology Unit, Department of Clinical and Experimental Medicine, University of Pisa, Via Roma, 67 -, 56126, Pisa, Italy
| | - Maurizio Mazzantini
- Rare Bone Diseases Clinic, Rheumatology Unit, Department of Clinical and Experimental Medicine, University of Pisa, Pisa, Italy
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2
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Zhao D, Sun L, Zheng W, Hu J, Zhou B, Wang O, Jiang Y, Xia W, Xing X, Li M. Novel mutation in LRP5 gene cause rare osteosclerosis: cases studies and literature review. Mol Genet Genomics 2023; 298:683-692. [PMID: 36971833 PMCID: PMC10133070 DOI: 10.1007/s00438-023-02008-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2022] [Accepted: 03/19/2023] [Indexed: 03/29/2023]
Abstract
AbstractTo study the effects of low-density lipoprotein receptor-related protein 5 (LRP5) gene mutations on bone, and to open up our view of LRP5 and Wnt pathways on bone mass regulation. Three patients with increased bone mineral density or thickened bone cortex were included, who were 30-year-old, 22-year-old and 50-year-old men, respectively. The latter two patients were son and father of a same family. The characteristics of bone X-rays were evaluated in detail. Bone turnover markers were detected, such as procollagen type 1 amino-terminal peptide (P1NP), alkaline phosphatase (ALP), and type 1 collagen carboxyl terminal peptide (β-CTX). Dual energy X-ray absorptiometry (DXA) was used to measure the bone mineral density (BMD) at lumbar spine and proximal femur of the patients. The targeted next-generation sequencing (NGS) technology was used to detect pathogenic gene mutations, which were further verified by Sanger sequencing. Moreover, the gene mutation spectrum and phenotypic characteristics of reported patients with LRP5 gain-of-function mutations were summarized by reviewing the literature. The main characteristics of the first patient were headache, facial paralysis, high BMD (lumbar vertebrae 1–4: 1.877 g/cm2, Z-score: 5.8; total hip: 1.705 g/cm2, Z-score: 5.7), slightly increased P1NP (87.0 ng/mL) and β-CTX (0.761 ng/mL) level, and with thickened bone cortex, especially the cranial vault. The latter two patients showed enlargement of the mandible and enlarged osseous prominence of the tours palatinus. X-rays showed that the bone cortex of skull and long bones were thickened. The bone turnover markers and BMD were normal. All three cases carried novel missense mutations in LRP5 gene, which were mutation in exon 3 (c.586 T > G, p.Trp196Gly) of the first patient, and mutation in exon 20 (c.4240C > A, p.Arg1414Ser) of the latter two patients. Combined with the reported literature, a total of 19 gain-of-function mutations in LRP5 were detected in 113 patients from 33 families. Hotspot mutations included c.724G > A, c.512G > T and c.758C > T. Furthermore, mutations in the exon 3 of LRP5 may cause severe phenotypes. LRP5 gain-of-function mutations can lead to rare autosomal dominant osteosclerosis type Ι (ADO Ι), which was characterized by increased bone mass and thickened bone cortex. In-depth research on the Wnt pathway will be benefit for discovering important mechanisms of bone mass regulation.
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3
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Bergen DJM, Maurizi A, Formosa MM, McDonald GLK, El-Gazzar A, Hassan N, Brandi ML, Riancho JA, Rivadeneira F, Ntzani E, Duncan EL, Gregson CL, Kiel DP, Zillikens MC, Sangiorgi L, Högler W, Duran I, Mäkitie O, Van Hul W, Hendrickx G. High Bone Mass Disorders: New Insights From Connecting the Clinic and the Bench. J Bone Miner Res 2023; 38:229-247. [PMID: 36161343 PMCID: PMC10092806 DOI: 10.1002/jbmr.4715] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/25/2022] [Revised: 09/05/2022] [Accepted: 09/22/2022] [Indexed: 02/04/2023]
Abstract
Monogenic high bone mass (HBM) disorders are characterized by an increased amount of bone in general, or at specific sites in the skeleton. Here, we describe 59 HBM disorders with 50 known disease-causing genes from the literature, and we provide an overview of the signaling pathways and mechanisms involved in the pathogenesis of these disorders. Based on this, we classify the known HBM genes into HBM (sub)groups according to uniform Gene Ontology (GO) terminology. This classification system may aid in hypothesis generation, for both wet lab experimental design and clinical genetic screening strategies. We discuss how functional genomics can shape discovery of novel HBM genes and/or mechanisms in the future, through implementation of omics assessments in existing and future model systems. Finally, we address strategies to improve gene identification in unsolved HBM cases and highlight the importance for cross-laboratory collaborations encompassing multidisciplinary efforts to transfer knowledge generated at the bench to the clinic. © 2022 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)
- Dylan J M Bergen
- School of Physiology, Pharmacology, and Neuroscience, Faculty of Life Sciences, University of Bristol, Bristol, UK.,Musculoskeletal Research Unit, Translational Health Sciences, Bristol Medical School, Faculty of Health Sciences, University of Bristol, Bristol, UK
| | - Antonio Maurizi
- Department of Biotechnological and Applied Clinical Sciences, University of L'Aquila, L'Aquila, Italy
| | - Melissa M Formosa
- Department of Applied Biomedical Science, Faculty of Health Sciences, University of Malta, Msida, Malta.,Center for Molecular Medicine and Biobanking, University of Malta, Msida, Malta
| | - Georgina L K McDonald
- School of Physiology, Pharmacology, and Neuroscience, Faculty of Life Sciences, University of Bristol, Bristol, UK
| | - Ahmed El-Gazzar
- Department of Paediatrics and Adolescent Medicine, Johannes Kepler University Linz, Linz, Austria
| | - Neelam Hassan
- Musculoskeletal Research Unit, Translational Health Sciences, Bristol Medical School, Faculty of Health Sciences, University of Bristol, Bristol, UK
| | | | - José A Riancho
- Department of Internal Medicine, Hospital U M Valdecilla, University of Cantabria, IDIVAL, Santander, Spain
| | - Fernando Rivadeneira
- Department of Internal Medicine, Erasmus University Medical Center, Rotterdam, The Netherlands
| | - Evangelia Ntzani
- Department of Hygiene and Epidemiology, Medical School, University of Ioannina, Ioannina, Greece.,Center for Evidence Synthesis in Health, Policy and Practice, Center for Research Synthesis in Health, School of Public Health, Brown University, Providence, RI, USA.,Institute of Biosciences, University Research Center of loannina, University of Ioannina, Ioannina, Greece
| | - Emma L Duncan
- Department of Twin Research & Genetic Epidemiology, School of Life Course Sciences, Faculty of Life Sciences and Medicine, King's College London, London, UK.,Department of Endocrinology, Guy's and St Thomas' NHS Foundation Trust, London, UK
| | - Celia L Gregson
- Musculoskeletal Research Unit, Translational Health Sciences, Bristol Medical School, Faculty of Health Sciences, University of Bristol, Bristol, UK
| | - Douglas P Kiel
- Marcus Institute for Aging Research, Hebrew SeniorLife and Department of Medicine Beth Israel Deaconess Medical Center and Harvard Medical School, Broad Institute of MIT & Harvard, Cambridge, MA, USA
| | - M Carola Zillikens
- Department of Internal Medicine, Erasmus University Medical Center, Rotterdam, The Netherlands
| | - Luca Sangiorgi
- Department of Rare Skeletal Diseases, IRCCS Rizzoli Orthopaedic Institute, Bologna, Italy
| | - Wolfgang Högler
- Department of Paediatrics and Adolescent Medicine, Johannes Kepler University Linz, Linz, Austria.,Institute of Metabolism and Systems Research, University of Birmingham, Birmingham, UK
| | | | - Outi Mäkitie
- Children's Hospital, University of Helsinki and Helsinki University Hospital, Helsinki, Finland.,Research Program for Clinical and Molecular Metabolism, Faculty of Medicine, University of Helsinki, Helsinki, Finland.,Folkhälsan Research Centre, Folkhälsan Institute of Genetics, Helsinki, Finland
| | - Wim Van Hul
- Department of Medical Genetics, University of Antwerp, Antwerp, Belgium
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4
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Zhang Z, Pan X, Chen M, Bai M. Wnt signalling in oral and maxillofacial diseases. Cell Biol Int 2021; 46:34-45. [PMID: 34643311 DOI: 10.1002/cbin.11708] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2021] [Revised: 08/31/2021] [Accepted: 10/08/2021] [Indexed: 02/05/2023]
Abstract
Wnts include more than 19 types of secreted glycoproteins that are involved in a wide range of pathological processes in oral and maxillofacial diseases. The transmission of Wnt signalling from the extracellular matrix into the nucleus includes canonical pathways and noncanonical pathways, which play an important role in tooth development, alveolar bone regeneration, and related diseases. In recent years, with the in-depth study of Wnt signalling in oral and maxillofacial-related diseases, many new conclusions and perspectives have been reached, and there are also some controversies. This article aims to summarise the roles of Wnt signalling in various oral diseases, including periodontitis, dental pulp disease, jaw disease, cleft palate, and abnormal tooth development, to provide researchers with a better and more comprehensive understanding of Wnts in oral and maxillofacial diseases.
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Affiliation(s)
- Zhaowei Zhang
- State Key Laboratory of Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, China
| | - Xinyue Pan
- State Key Laboratory of Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, China
| | - Mingyang Chen
- State Key Laboratory of Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, China
| | - Mingru Bai
- State Key Laboratory of Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, China.,National Clinical Research Center for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, China.,Department of Endodontics, West China Hospital of Stomatology, Sichuan University, Chengdu, China
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5
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Yamada M, Kubota K, Uchida A, Yagihashi T, Kawasaki M, Suzuki H, Uehara T, Takenouchi T, Kurosaka H, Kosaki K. Fork-shaped mandibular incisors as a novel phenotype of LRP5-associated disorder. Am J Med Genet A 2021; 185:1544-1549. [PMID: 33619830 DOI: 10.1002/ajmg.a.62132] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2020] [Revised: 01/10/2021] [Accepted: 02/06/2021] [Indexed: 11/10/2022]
Abstract
The LRP5 gene encodes a Wnt signaling receptor to which Wnt binds directly. In humans, pathogenic monoallelic variants in LRP5 have been associated with increased bone density and exudative vitreoretinopathy. In mice, LRP5 plays a role in tooth development, including periodontal tissue stability and cementum formation. Here, we report a 14-year-old patient with a de novo non-synonymous variant, p.(Val1245Met), in LRP5 who exhibited mildly reduced bone density and mild exudative vitreoretinopathy together with a previously unreported phenotype consisting of dental abnormalities that included fork-like small incisors with short roots and an anterior open bite, molars with a single root, and severe taurodontism. In that exudative vitreoretinopathy has been reported to be associated with heterozygous loss-of-function variants of LRP5 and that our patient reported here with the p.(Val1245Met) variant had mild exudative vitreoretinopathy, the variant can be considered as an incomplete loss-of-function variant. Alternatively, the p.(Val1245Met) variant can be considered as exerting a dominant-negative effect, as no patients with truncating LRP5 variants and exudative vitreoretinopathy have been reported to exhibit dental anomalies. The documentation of dental anomalies in the presently reported patient strongly supports the notion that LRP5 plays a critical role in odontogenesis in humans, similar to its role in mice.
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Affiliation(s)
- Mamiko Yamada
- Center for Medical Genetics, Keio University School of Medicine, Tokyo, Japan
| | - Kazumi Kubota
- Department of Plastic and Reconstructive Surgery, Keio University School of Medicine, Tokyo, Japan.,Department of Special Needs Dentistry, Division of Hygiene and Oral Health, Showa University School of Dentistry, Tokyo, Japan
| | - Atsuro Uchida
- Department of Ophthalmology, Keio University School of Medicine, Tokyo, Japan
| | - Tatsuhiko Yagihashi
- Center for Medical Genetics, Keio University School of Medicine, Tokyo, Japan
| | | | - Hisato Suzuki
- Center for Medical Genetics, Keio University School of Medicine, Tokyo, Japan
| | - Tomoko Uehara
- Center for Medical Genetics, Keio University School of Medicine, Tokyo, Japan.,Department of Pediatrics, Central Hospital, Aichi Developmental Disability Center, Kasugai, Aichi, Japan
| | - Toshiki Takenouchi
- Department of Pediatrics, Keio University School of Medicine, Tokyo, Japan
| | - Hiroshi Kurosaka
- Department of Orthodontics and Dentofacial Orthopedics, Graduate School of Dentistry, Osaka University, Osaka, Japan
| | - Kenjiro Kosaki
- Center for Medical Genetics, Keio University School of Medicine, Tokyo, Japan
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Abstract
The phenotypic trait of high bone mass (HBM) is an excellent example of the nexus between common and rare disease genetics. HBM may arise from carriage of many 'high bone mineral density [BMD]'-associated alleles, and certainly the genetic architecture of individuals with HBM is enriched with high BMD variants identified through genome-wide association studies of BMD. HBM may also arise as a monogenic skeletal disorder, due to abnormalities in bone formation, bone resorption, and/or bone turnover. Individuals with monogenic disorders of HBM usually, though not invariably, have other skeletal abnormalities (such as mandible enlargement) and thus are best regarded as having a skeletal dysplasia rather than just isolated high BMD. A binary etiological division of HBM into polygenic vs. monogenic, however, would be excessively simplistic: the phenotype of individuals carrying rare variants of large effect can still be modified by their common variant polygenic background, and by the environment. HBM disorders-whether predominantly polygenic or monogenic in origin-are not only interesting clinically and genetically: they provide insights into bone processes that can be exploited therapeutically, with benefits both for individuals with these rare bone disorders and importantly for the many people affected by the commonest bone disease worldwide-i.e., osteoporosis. In this review we detail the genetic architecture of HBM; we provide a conceptual framework for considering HBM in the clinical context; and we discuss monogenic and polygenic causes of HBM with particular emphasis on anabolic causes of HBM.
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Affiliation(s)
- Celia L. Gregson
- Musculoskeletal Research Unit, Translational Health Sciences, Bristol Medical School, University of Bristol, Bristol, United Kingdom
| | - Emma L. Duncan
- Department of Twin Research & Genetic Epidemiology, School of Life Course Sciences, Faculty of Life Sciences and Medicine, King’s College London, London, United Kingdom
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7
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Lrp4 Mediates Bone Homeostasis and Mechanotransduction through Interaction with Sclerostin In Vivo. iScience 2019; 20:205-215. [PMID: 31585407 PMCID: PMC6817631 DOI: 10.1016/j.isci.2019.09.023] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2019] [Revised: 08/06/2019] [Accepted: 09/13/2019] [Indexed: 01/18/2023] Open
Abstract
Wnt signaling plays a key role in regulating bone remodeling. In vitro studies suggest that sclerostin's inhibitory action on Lrp5 is facilitated by the membrane-associated receptor Lrp4. We generated an Lrp4 R1170W knockin mouse model (Lrp4KI), based on a published mutation in patients with high bone mass (HBM). Lrp4KI mice have an HBM phenotype (assessed radiographically), including increased bone strength and formation. Overexpression of a Sost transgene had osteopenic effects in Lrp4-WT but not Lrp4KI mice. Conversely, sclerostin inhibition had blunted osteoanabolic effects in Lrp4KI mice. In a disuse-induced bone wasting model, Lrp4KI mice exhibit significantly less bone loss than wild-type (WT) mice. In summary, mice harboring the Lrp4-R1170W missense mutation recapitulate the human HBM phenotype, are less sensitive to altered sclerostin levels, and are protected from disuse-induced bone loss. Lrp4 is an attractive target for pharmacological targeting aimed at increasing bone mass and preventing bone loss due to disuse. Missense mutation in the third beta-propeller of Lrp4 improve bone properties The R1170W mutation in Lrp4 interferes with sclerostin inhibition in vivo The R1170W Lrp4 mutation alters the bone wasting effects of mechanical disuse
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8
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Witcher PC, Miner SE, Horan DJ, Bullock WA, Lim KE, Kang KS, Adaniya AL, Ross RD, Loots GG, Robling AG. Sclerostin neutralization unleashes the osteoanabolic effects of Dkk1 inhibition. JCI Insight 2018; 3:98673. [PMID: 29875318 DOI: 10.1172/jci.insight.98673] [Citation(s) in RCA: 52] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2017] [Accepted: 04/26/2018] [Indexed: 12/12/2022] Open
Abstract
The WNT pathway has become an attractive target for skeletal therapies. High-bone-mass phenotypes in patients with loss-of-function mutations in the LRP5/6 inhibitor Sost (sclerosteosis), or in its downstream enhancer region (van Buchem disease), highlight the utility of targeting Sost/sclerostin to improve bone properties. Sclerostin-neutralizing antibody is highly osteoanabolic in animal models and in human clinical trials, but antibody-based inhibition of another potent LRP5/6 antagonist, Dkk1, is largely inefficacious for building bone in the unperturbed adult skeleton. Here, we show that conditional deletion of Dkk1 from bone also has negligible effects on bone mass. Dkk1 inhibition increases Sost expression, suggesting a potential compensatory mechanism that might explain why Dkk1 suppression lacks anabolic action. To test this concept, we deleted Sost from osteocytes in, or administered sclerostin neutralizing antibody to, mice with a Dkk1-deficient skeleton. A robust anabolic response to Dkk1 deletion was manifest only when Sost/sclerostin was impaired. Whole-body DXA scans, μCT measurements of the femur and spine, histomorphometric measures of femoral bone formation rates, and biomechanical properties of whole bones confirmed the anabolic potential of Dkk1 inhibition in the absence of sclerostin. Further, combined administration of sclerostin and Dkk1 antibody in WT mice produced a synergistic effect on bone gain that greatly exceeded individual or additive effects of the therapies, confirming the therapeutic potential of inhibiting multiple WNT antagonists for skeletal health. In conclusion, the osteoanabolic effects of Dkk1 inhibition can be realized if sclerostin upregulation is prevented. Anabolic therapies for patients with low bone mass might benefit from a strategy that accounts for the compensatory milieu of WNT inhibitors in bone tissue.
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Affiliation(s)
- Phillip C Witcher
- Department of Anatomy & Cell Biology, Indiana University School of Medicine, Indianapolis, Indiana, USA
| | - Sara E Miner
- Department of Anatomy & Cell Biology, Indiana University School of Medicine, Indianapolis, Indiana, USA
| | - Daniel J Horan
- Department of Anatomy & Cell Biology, Indiana University School of Medicine, Indianapolis, Indiana, USA
| | - Whitney A Bullock
- Department of Anatomy & Cell Biology, Indiana University School of Medicine, Indianapolis, Indiana, USA
| | - Kyung-Eun Lim
- Department of Anatomy & Cell Biology, Indiana University School of Medicine, Indianapolis, Indiana, USA
| | - Kyung Shin Kang
- Department of Anatomy & Cell Biology, Indiana University School of Medicine, Indianapolis, Indiana, USA.,Department of Physical Sciences & Engineering, Anderson University, Anderson, Indiana, USA
| | - Alison L Adaniya
- Department of Anatomy & Cell Biology, Indiana University School of Medicine, Indianapolis, Indiana, USA
| | - Ryan D Ross
- Department of Cell & Molecular Medicine, Rush University Medical Center, Chicago, Illinois, USA
| | - Gabriela G Loots
- Biology and Biotechnology Division, Lawrence Livermore National Laboratory, Livermore, California, USA.,School of Natural Sciences, University of California, Merced, California, USA
| | - Alexander G Robling
- Department of Anatomy & Cell Biology, Indiana University School of Medicine, Indianapolis, Indiana, USA.,Richard L. Roudebush Veterans Affairs Medical Center, Indianapolis, Indiana, USA.,Department of Biomedical Engineering, Indiana University-Purdue University Indianapolis, Indianapolis, Indiana, USA.,Indiana Center for Musculoskeletal Health, Indianapolis, Indiana, USA
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9
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Roetzer KM, Uyanik G, Brehm A, Zwerina J, Zandieh S, Czech T, Roschger P, Misof BM, Klaushofer K. Novel familial mutation of LRP5 causing high bone mass: Genetic analysis, clinical presentation, and characterization of bone matrix mineralization. Bone 2018; 107:154-160. [PMID: 29208525 DOI: 10.1016/j.bone.2017.12.002] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/11/2017] [Revised: 12/01/2017] [Accepted: 12/01/2017] [Indexed: 12/29/2022]
Abstract
The Wnt signalling pathway is a critical regulator of bone mass and quality. Several heterozygous mutations in the LRP5 gene, a Wnt co-receptor, causing high bone mass (LRP5-HBM) have been described to date. The pathogenic mechanism is thought to be a gain-of-function caused by impaired inhibition of the canonical Wnt signalling pathway, thereby leading to increased bone formation. We report the cases of two affected family members, a 53-year-old mother and her 23-year-old daughter, with high bone mass (T-scores mother: lumbar spine 11.4, femoral neck 10.5; T-scores daughter: lumbar spine 5.4, femoral neck 8.7), increased calvarial thickness, and thickened cortices of the long bones but no history of fractures. Whereas the mother did not show any indications of the mutation, the daughter suffered from congenital hearing impairment resulting in cochlear implantation, recurrent facial palsy, and migraine. In addition, she had stenosis of the foramen magnum. In both individuals, we detected a novel heterozygous duplication of six basepairs in the LRP5 gene, resulting in an insertion of two amino acids, very likely associated with a gain-of-function. When the daughter had part of the occipital bone surgically removed, the bone sample was used for the visualization of bone lamellar structure and bone cells as well as the measurement of bone mineralization density distribution (BMDD). The bone sample revealed two distinctly different regions: an intra-cortical region with osteonal remodeling, typical osteonal lamellar orientation, associated with relatively higher heterogeneity of bone matrix mineralization, and another periosteal region devoid of bone remodeling, with parallel bone lamellae and lower heterogeneity of mineralization. In conclusion, we present data on bone tissue and material level from an LRP5-HBM patient with a novel mutation in the LRP5 gene. Our findings indicate normal morphology of osteoclasts and osteoblasts as well as normal mineralization in skull bone in LRP5-HBM.
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Affiliation(s)
- K M Roetzer
- Ludwig Boltzmann Institute of Osteology at the Hanusch Hospital of WGKK and AUVA Trauma Centre Meidling, 1st Medical Department, Hanusch Hospital, Vienna, Austria; Center for Medical Genetics, Hanusch Hospital, Vienna, Austria; Medical Faculty, Sigmund Freud University, Vienna, Austria
| | - G Uyanik
- Ludwig Boltzmann Institute of Osteology at the Hanusch Hospital of WGKK and AUVA Trauma Centre Meidling, 1st Medical Department, Hanusch Hospital, Vienna, Austria; Center for Medical Genetics, Hanusch Hospital, Vienna, Austria; Medical Faculty, Sigmund Freud University, Vienna, Austria
| | - A Brehm
- 1st Medical Department, Hanusch Hospital, Vienna, Austria
| | - J Zwerina
- Ludwig Boltzmann Institute of Osteology at the Hanusch Hospital of WGKK and AUVA Trauma Centre Meidling, 1st Medical Department, Hanusch Hospital, Vienna, Austria; 1st Medical Department, Hanusch Hospital, Vienna, Austria
| | - S Zandieh
- Ludwig Boltzmann Institute of Osteology at the Hanusch Hospital of WGKK and AUVA Trauma Centre Meidling, 1st Medical Department, Hanusch Hospital, Vienna, Austria; Department of Radiology and Nuclear Medicine, Hanusch Hospital, Vienna, Austria
| | - T Czech
- Department of Neurosurgery, Medical University of Vienna, Vienna, Austria
| | - P Roschger
- Ludwig Boltzmann Institute of Osteology at the Hanusch Hospital of WGKK and AUVA Trauma Centre Meidling, 1st Medical Department, Hanusch Hospital, Vienna, Austria
| | - B M Misof
- Ludwig Boltzmann Institute of Osteology at the Hanusch Hospital of WGKK and AUVA Trauma Centre Meidling, 1st Medical Department, Hanusch Hospital, Vienna, Austria.
| | - K Klaushofer
- Ludwig Boltzmann Institute of Osteology at the Hanusch Hospital of WGKK and AUVA Trauma Centre Meidling, 1st Medical Department, Hanusch Hospital, Vienna, Austria; 1st Medical Department, Hanusch Hospital, Vienna, Austria
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