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Ekhzaimy AA, Alyusuf EY, Alswailem M, Alzahrani AS. A Novel Mutation in a Gene Causes Sclerosteosis in a Family of Mediterranean Origin. Medicina (B Aires) 2022; 58:medicina58020202. [PMID: 35208525 PMCID: PMC8878747 DOI: 10.3390/medicina58020202] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2021] [Revised: 01/21/2022] [Accepted: 01/26/2022] [Indexed: 11/17/2022] Open
Abstract
Background and Objectives: Sclerostin is an SOST gene product that inhibits osteoblast activity and prevents excessive bone formation by antagonizing the Wnt signaling pathway. Sclerosteosis has been linked to loss of function mutations in the SOST gene. It is a rare autosomal recessive disorder characterized by craniotubular hyperostosis and can lead to fatal cerebellar herniation. Our aim is to describe the clinical and radiological features and the new underlying SOST mutation in a patient with sclerosteosis. Case: A 25-year-old female who was referred to the endocrine clinic for suspected excess growth hormone. The patient complained of headaches, progressive blurred vision, hearing disturbances, increased size of feet, proptosis, and protrusion of the chin. She had normal antenatal history except for syndactyly. Images showed diffuse osseous thickening and high bone mineral density. Biochemical and hormonal tests were normal. Due to progressive compressive optic neuropathy, optic nerve fenestration with decompression hemicraniotomy was performed. Sclerosteosis was suspected due to the predominant craniotubular hyperostosis with syndactyly. Using peripheral leucocyte DNA, genomic sequencing of the SOST gene was performed. This identified a novel deletion homozygous mutation in the SOST gene (c.387delG, p.Asp131ThrfsTer116) which disrupts sclerostin function, causing sclerosteosis. Conclusions: Discovery of the molecular basis of sclerosteosis represents an important advance in the diagnosis and management of this fatal disease.
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Affiliation(s)
- Aishah A. Ekhzaimy
- Division of Endocrinology, Department of Internal Medicine, College of Medicine, King Saud University, Riyadh 11437, Saudi Arabia;
- Correspondence:
| | - Ebtihal Y. Alyusuf
- Division of Endocrinology, Department of Internal Medicine, College of Medicine, King Saud University, Riyadh 11437, Saudi Arabia;
| | - Meshael Alswailem
- Division of Molecular Endocrinology, Department of Molecular Oncology, King Faisal Specialist Hospital and Research Centre, Riyadh 11437, Saudi Arabia; (M.A.); (A.S.A.)
| | - Ali S. Alzahrani
- Division of Molecular Endocrinology, Department of Molecular Oncology, King Faisal Specialist Hospital and Research Centre, Riyadh 11437, Saudi Arabia; (M.A.); (A.S.A.)
- Department of Medicine, King Faisal Specialist Hospital and Research Center, Riyadh 11437, Saudi Arabia
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Genetics and Genomics of SOST: Functional Analysis of Variants and Genomic Regulation in Osteoblasts. Int J Mol Sci 2021; 22:ijms22020489. [PMID: 33419004 PMCID: PMC7825314 DOI: 10.3390/ijms22020489] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2020] [Revised: 12/28/2020] [Accepted: 12/31/2020] [Indexed: 11/17/2022] Open
Abstract
SOST encodes the sclerostin protein, which acts as a key extracellular inhibitor of the canonical Wnt pathway in bone, playing a crucial role in skeletal development and bone homeostasis. The objective of this work was to assess the functionality of two variants previously identified (the rare variant rs570754792 and the missense variant p.Val10Ile) and to investigate the physical interactors of the SOST proximal promoter region in bone cells. Through a promoter luciferase reporter assay we show that the minor allele of rs570754792, a variant located in the extended TATA box motif, displays a significant decrease in promoter activity. Likewise, through western blot studies of extracellular and intracellular sclerostin, we observe a reduced expression of the p.Val10Ile mutant protein. Finally, using a circular chromosome conformation capture assay (4C-seq) in 3 bone cell types (MSC, hFOB, Saos-2), we have detected physical interactions between the SOST proximal promoter and the ECR5 enhancer, several additional enhancers located between EVT4 and MEOX1 and a distant region containing exon 18 of DHX8. In conclusion, SOST presents functional regulatory and missense variants that affect its expression and displays physical contacts with far reaching genomic sequences, which may play a role in its regulation within bone cells.
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Whyte MP, Deepak Amalnath S, McAlister WH, Pedapati R, Muthupillai V, Duan S, Huskey M, Bijanki VN, Mumm S. Sclerosteosis: Report of type 1 or 2 in three Indian Tamil families and literature review. Bone 2018; 116:321-332. [PMID: 30077757 DOI: 10.1016/j.bone.2018.07.022] [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: 05/01/2018] [Revised: 07/05/2018] [Accepted: 07/25/2018] [Indexed: 01/08/2023]
Abstract
Sclerosteosis (SOST) refers to two extremely rare yet similar skeletal dysplasias featuring a diffusely radiodense skeleton together with congenital syndactyly. SOST1 is transmitted as an autosomal recessive (AR) trait and to date caused by ten homozygous loss-of-function mutations within the gene SOST that encodes the inhibitor of Wnt-mediated bone formation, sclerostin. SOST2 is transmitted as an autosomal dominant (AD) or AR trait and to date caused by one heterozygous or two homozygous loss-of-function mutation(s), respectively, within the gene LRP4 that encodes the sclerostin interaction protein, low-density lipoprotein receptor-related protein 4 (LRP4). Herein, we investigated two teenagers and one middle-aged man with SOST in three families living in the state of Tamil Nadu in southern India. Next generation sequencing of their genomic DNA using our high bone density gene panel revealed SOST1 in the teenagers caused by a unique homozygous nonsense SOST mutation (c.129C > G, p.Tyr43X) and SOST2 in the man caused by homozygosity for one of the two known homozygous missense LRP4 mutations (c.3508C > T, p.Arg1170Trp). He becomes the fourth individual and the first non-European recognized with SOST2. His clinical course was milder than the life-threatening SOST1 demonstrated by the teenagers who suffered blindness, deafness, and raised intracranial pressure, yet his congenital syndactyly was more striking by featuring bony fusion of digits. All three patients were from consanguineous families and heterozygosity for the SOST mutation was documented in the mothers of both teenagers. Thus, on the endogamous genetic background of Indian Tamils, SOST1 from sclerostin deficiency compared to SOST2 from LRP4 deactivation is a more severe and life-threatening disorder featuring complications due to osteosclerosis of especially the skull. In contrast, the syndactyly of SOST2 is particularly striking by involving bony fusion of some digits. Both the SOST and LRP4 mutations in this ethnic population likely reflect genetic founders.
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Affiliation(s)
- Michael P Whyte
- Center for Metabolic Bone Disease and Molecular Research, Shriners Hospital for Children, St. Louis, MO 63110, USA; Division of Bone and Mineral Diseases, Department of Internal Medicine, Washington University School of Medicine at Barnes-Jewish Hospital, St. Louis, MO 63110, USA.
| | - S Deepak Amalnath
- Department of Medicine, Jawaharlal Institute of Postgraduate Medical Education and Research (JIPMER), Pondicherry 605006, India.
| | - William H McAlister
- Mallinckrodt Institute of Radiology, Washington University School of Medicine at St. Louis Children's Hospital, St. Louis, MO 63110, USA.
| | - Radhakrishna Pedapati
- Department of Medicine, Jawaharlal Institute of Postgraduate Medical Education and Research (JIPMER), Pondicherry 605006, India.
| | - Vivekanandan Muthupillai
- Department of Medicine, Jawaharlal Institute of Postgraduate Medical Education and Research (JIPMER), Pondicherry 605006, India.
| | - Shenghui Duan
- Division of Bone and Mineral Diseases, Department of Internal Medicine, Washington University School of Medicine at Barnes-Jewish Hospital, St. Louis, MO 63110, USA.
| | - Margaret Huskey
- Division of Bone and Mineral Diseases, Department of Internal Medicine, Washington University School of Medicine at Barnes-Jewish Hospital, St. Louis, MO 63110, USA.
| | - Vinieth N Bijanki
- Center for Metabolic Bone Disease and Molecular Research, Shriners Hospital for Children, St. Louis, MO 63110, USA.
| | - Steven Mumm
- Center for Metabolic Bone Disease and Molecular Research, Shriners Hospital for Children, St. Louis, MO 63110, USA; Division of Bone and Mineral Diseases, Department of Internal Medicine, Washington University School of Medicine at Barnes-Jewish Hospital, St. Louis, MO 63110, USA.
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Sebastian A, Loots GG. Genetics of Sost/SOST in sclerosteosis and van Buchem disease animal models. Metabolism 2018; 80:38-47. [PMID: 29080811 DOI: 10.1016/j.metabol.2017.10.005] [Citation(s) in RCA: 46] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/26/2017] [Revised: 10/02/2017] [Accepted: 10/04/2017] [Indexed: 12/14/2022]
Abstract
Sclerosteosis and van Buchem disease (VBD) are two rare autosomal recessive disorders that results from osteoblast hyperactivity, in which progressive bone overgrowth leads to very dense bones, distortion of the face, and entrapment of cranial nerves. Sclerosteosis is caused by loss-of-function mutations in the SOST gene which encodes a secreted glycoprotein, sclerostin. VBD is caused by a noncoding deletion that removes a SOST-specific regulatory element in bone. In bone, SOST is expressed predominantly by osteocytes and sclerostin suppresses bone formation by inhibiting the canonical Wnt signaling pathway. Here we describe how human genetics studies in sclerosteosis and VBD patients, in combination with the generation of transgenic and knockout mice, has led to a better understanding of the role of sclerostin in bone metabolism.
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Affiliation(s)
- Aimy Sebastian
- Biology and Biotechnology Division, Lawrence Livermore National Laboratory, 7000 East Avenue, L-452, Livermore, CA 94550, USA
| | - Gabriela G Loots
- Biology and Biotechnology Division, Lawrence Livermore National Laboratory, 7000 East Avenue, L-452, Livermore, CA 94550, USA; School of Natural Sciences, University of California, Merced, CA 95343, USA.
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Bisson SK, Ung RV, Mac-Way F. Role of the Wnt/ β-Catenin Pathway in Renal Osteodystrophy. Int J Endocrinol 2018; 2018:5893514. [PMID: 29808090 PMCID: PMC5901476 DOI: 10.1155/2018/5893514] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/25/2018] [Accepted: 03/08/2018] [Indexed: 12/17/2022] Open
Abstract
Vascular calcification and bone fragility are common and interrelated health problems that affect chronic kidney disease (CKD) patients. Bone fragility, which leads to higher risk of fracture and mortality, arises from the abnormal bone remodeling and mineralization that are seen in chronic kidney disease. Recently, sclerostin and Dickkopf-related protein 1 were suggested to play a significant role in CKD-related bone disease as they are known inhibitors of the Wnt pathway, thus preventing bone formation. This review focuses on new knowledge about the Wnt pathway in bone, how its function is affected by chronic kidney disease and how this affects bone structure. Expression of components and inhibitors of the Wnt pathway has been shown to be affected by the loss of kidney function, and a better understanding of the bone effects of Wnt pathway inhibitors could allow the development of new therapies to prevent bone fragility in this population.
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Affiliation(s)
- Sarah-Kim Bisson
- Faculty and Department of Medicine, CHU de Québec Research Center, L'Hôtel-Dieu de Québec Hospital, Endocrinology and Nephrology Axis, Université Laval, Quebec, Canada
| | - Roth-Visal Ung
- Faculty and Department of Medicine, CHU de Québec Research Center, L'Hôtel-Dieu de Québec Hospital, Endocrinology and Nephrology Axis, Université Laval, Quebec, Canada
| | - Fabrice Mac-Way
- Faculty and Department of Medicine, CHU de Québec Research Center, L'Hôtel-Dieu de Québec Hospital, Endocrinology and Nephrology Axis, Université Laval, Quebec, Canada
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Baas M, Stubbs AP, van Zessen DB, Galjaard RJH, van der Spek PJ, Hovius SER, van Nieuwenhoven CA. Identification of Associated Genes and Diseases in Patients With Congenital Upper-Limb Anomalies: A Novel Application of the OMT Classification. J Hand Surg Am 2017; 42:533-545.e4. [PMID: 28669419 DOI: 10.1016/j.jhsa.2017.03.043] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/05/2016] [Revised: 01/09/2017] [Accepted: 03/30/2017] [Indexed: 02/02/2023]
Abstract
PURPOSE Congenital upper-limb anomalies (CULA) can present as a part of a syndrome or association. There is a wide spectrum of CULA, each of which might be related to different diseases. The structure provided by the Oberg, Manske, and Tonkin (OMT) classification could aid in differential diagnosis formulation in patients with CULA. The aims of this study were to review the Human Phenotype Ontology (HPO) project database for diseases and causative genes related to the CULA described in the OMT classification and to develop a methodology for differential diagnosis formulation based on the observed congenital anomalies, CulaPhen. METHODS We reviewed the HPO database for all diseases, including causative genes related to CULA. All CULA were classified according to the OMT classification; associated non-hand phenotypes were classified into 12 anatomical groups. We analyzed the contribution of each anatomical group to a given disease and developed a tool for differential diagnosis formulation based on these contributions. We compared our results with cases from the literature and with a current HPO tool, Phenomizer. RESULTS In total, 514 hand phenotypes were obtained, 384 of which could be classified in the OMT classification. A total of 1,403 diseases could be related to those CULA. A comparison with 10 recently published cases with CULA revealed that the presented phenotype matched the descriptions in our dataset. The differential diagnosis produced using our methodology was more accurate than Phenomizer in 4 of 5 examples. CONCLUSIONS The OMT classification can be used to describe hand anomalies that may present in over 1,400 diseases. CulaPhen was developed to provide a (hand) phenotype-based differential diagnosis. Differential diagnosis formulation based on the proposed system outperforms the system in current use. CLINICAL RELEVANCE This study illustrates that the OMT diagnoses, either individually or combined, can be cross-referenced with different diseases and syndromes. Therefore, use of the OMT classification can aid differential diagnosis formulation for CULA patients.
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Affiliation(s)
- Martijn Baas
- Department of Plastic and Reconstructive Surgery and Hand Surgery, Erasmus MC, Erasmus University Medical Center, Rotterdam, The Netherlands
| | - Andrew P Stubbs
- Department of Clinical Genetics, Erasmus MC, Erasmus University Medical Center, Rotterdam, The Netherlands
| | - David B van Zessen
- Department of Clinical Genetics, Erasmus MC, Erasmus University Medical Center, Rotterdam, The Netherlands
| | - Robert-Jan H Galjaard
- Department of Bioinformatics, Erasmus MC, Erasmus University Medical Center, Rotterdam, The Netherlands
| | - Peter J van der Spek
- Department of Clinical Genetics, Erasmus MC, Erasmus University Medical Center, Rotterdam, The Netherlands
| | - Steven E R Hovius
- Department of Plastic and Reconstructive Surgery and Hand Surgery, Erasmus MC, Erasmus University Medical Center, Rotterdam, The Netherlands
| | - Christianne A van Nieuwenhoven
- Department of Plastic and Reconstructive Surgery and Hand Surgery, Erasmus MC, Erasmus University Medical Center, Rotterdam, The Netherlands.
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van Lierop AH, Appelman-Dijkstra NM, Papapoulos SE. Sclerostin deficiency in humans. Bone 2017; 96:51-62. [PMID: 27742500 DOI: 10.1016/j.bone.2016.10.010] [Citation(s) in RCA: 57] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/12/2016] [Revised: 09/09/2016] [Accepted: 10/10/2016] [Indexed: 01/11/2023]
Abstract
Sclerosteosis and van Buchem disease are two rare bone sclerosing dysplasias caused by genetic defects in the synthesis of sclerostin. In this article we review the demographic, clinical, biochemical, radiological, and histological characteristics of patients with sclerosteosis and van Buchem disease that led to a better understanding of the role of sclerostin in bone metabolism in humans and we discuss the relevance of these findings for the development of new therapeutics for the treatment of patients with osteoporosis.
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Affiliation(s)
- Antoon H van Lierop
- Center for Bone Quality, Leiden University Medical Center, Leiden, The Netherlands
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He W, Chen C, Pan C, Zhang M, Yu X, Wang D, Hu S. Sclerosteosis caused by a novel nonsense mutation of
SOST
in a consanguineous family. Clin Genet 2015; 89:205-9. [DOI: 10.1111/cge.12655] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2015] [Revised: 08/14/2015] [Accepted: 08/14/2015] [Indexed: 11/29/2022]
Affiliation(s)
- Wen‐Tao He
- Department of Endocrinology and Metabolism Wuhan P. R. China
| | - Chen Chen
- Department of Cardiology Wuhan P. R. China
| | - Chu Pan
- Department of RadiologyTongji Hospital, Tongji Medical College, Huazhong University of Science and Technology Wuhan P. R. China
| | - Mu‐Xun Zhang
- Department of Endocrinology and Metabolism Wuhan P. R. China
| | - Xue‐Feng Yu
- Department of Endocrinology and Metabolism Wuhan P. R. China
| | | | - Shu‐Hong Hu
- Department of Endocrinology and Metabolism Wuhan P. R. China
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