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Mumm S, Paz-Ibarra JL, Campeau PM, Garrido-Carrasco E, Baker JC, Pino-Nina E, Duan S, McAlister WH, Whyte MP. Transforming growth factor, beta-2 gene mutation causes autosomal dominant Camurati-Engelmann disease, type 2 (OMIM % 606631). Bone 2025; 197:117477. [PMID: 40204055 DOI: 10.1016/j.bone.2025.117477] [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: 01/14/2025] [Revised: 03/18/2025] [Accepted: 03/31/2025] [Indexed: 04/11/2025]
Abstract
Camurati-Engelmann disease, type 1 (CED1, OMIM # 131300) is the rare autosomal dominant skeletal dysplasia caused by select heterozygous loss-of-function defects within the gene TGFB1, which encodes transforming growth factor beta 1 (TGFB1). CED1 mutations are found in TGFB1 exons 1-4 that form the latency-associated peptide (LAP) of pro-TGFB1. Consequently, skeletal action of TGFB1 increases and thereby enhances bone formation manifest clinically as "progressive diaphyseal dysplasia". Beginning 24 years ago negative TGFB1 analysis suggested rare genetic heterogeneity for CED, and Online Mendelian Inheritance In Man designated, of unknown etiology, "CED2" (OMIM % 606631). In 2024, three sporadic occurrences considered CED2 were reported to harbor either of two mutations of TGFB2, which encodes the LAP of transforming growth factor beta 2 (TGFB2). Herein, three adults (father, son, daughter) having the CED2 phenotype in a Peruvian family revealed a novel missense variant (c.108G > T, p.R36S) within the TGFB2 LAP domain. Debilitating painful skeletal disease featuring hyperostosis of entire long bones, worse in the men, presented early in childhood. Aminobisphosphonate therapy seemed helpful. Their TGFB2 variant was within a highly conserved domain across species, absent in the gnomAD database, "possibly damaging" by Polyphen-2, not tolerated by SIFT, homologous with TGFB1 at the same amino acid position (R36) as one reported TGFB2 mutation, co-segregated as autosomal dominant, and "likely pathogenic" per ACMG guidelines.
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Affiliation(s)
- Steven Mumm
- Division of Bone and Mineral Diseases, Department of Internal Medicine, Washington University School of Medicine, St Louis, MO 63110, USA; Center for Metabolic Bone Disease and Molecular Research, Shriners Hospitals for Children-St. Louis, St. Louis, MO 63110, USA.
| | - José L Paz-Ibarra
- Department of Endocrinology, Hospital Nacional Edgardo Rebagliati Martins, Lima, Peru; Department of Medicine, Universidad Nacional Mayor de San Marcos, Lima, Peru.
| | - Philippe M Campeau
- Department of Pediatrics, University of Montreal, Montreal, Quebec H3T 1C5, Canada.
| | | | - Jonathan C Baker
- Musculoskeletal Section, Mallinckrodt Institute of Radiology, Washington University School of Medicine, St. Louis, MO 63110, USA.
| | - Ethel Pino-Nina
- Department of Medicine, Universidad Nacional Mayor de San Marcos, Lima, Peru
| | - Shenghui Duan
- Division of Bone and Mineral Diseases, Department of Internal Medicine, Washington University School of Medicine, St Louis, MO 63110, USA.
| | - William H McAlister
- Pediatric Radiology Section, Mallinckrodt Institute of Radiology at St. Louis Children's Hospital, Washington University School of Medicine, St. Louis, MO 63110, USA.
| | - Michael P Whyte
- Division of Bone and Mineral Diseases, Department of Internal Medicine, Washington University School of Medicine, St Louis, MO 63110, USA; Center for Metabolic Bone Disease and Molecular Research, Shriners Hospitals for Children-St. Louis, St. Louis, MO 63110, USA.
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2
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Polyzos SA, Anastasilakis K, Cundy T, Kita M. Long-Term Denosumab Treatment in Adults with Juvenile Paget Disease. Calcif Tissue Int 2025; 116:60. [PMID: 40223037 PMCID: PMC11994531 DOI: 10.1007/s00223-025-01370-0] [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: 02/14/2025] [Accepted: 04/01/2025] [Indexed: 04/15/2025]
Abstract
Juvenile Paget disease (JPD) is a very rare disease, mainly caused by biallelic inactivating mutations in the TNFRSF11B gene that encodes osteoprotegerin. Owing to its rarity, the treatment of JPD is largely empirical. Accelerated bone turnover as assessed by biochemical markers, such as alkaline phosphatase (ALP), can be suppressed by bisphosphonate treatment, but it relapses if bisphosphonate treatment is discontinued. In this report, we describe our experience with long-term denosumab treatment in two adults with JPD, homozygous for the "Balkan" mutation (966_969delTGACinsCTT) in TNFRSF11B. Subject 1 started denosumab in age 35 and subject 2 in age 34. Both continue treatment until today, for 13.5 and 12 years, respectively. ALP was steadily normalized in both. Bone pain decreased and mobility improved. Hearing did not further deteriorate and no new fracture occurred. Vision remained unchanged in subject 2, but subject 1 experienced sudden vision loss of the right eye at age 46, which was successfully managed with intravitreal treatment with anti-vascular endothelial growth factor medications. In conclusion, long-term denosumab administration in adults with JPD, who had been previously treated with bisphosphonates, was safe and effective in terms of the skeletal disease, but it may not prevent the emergence of retinopathy.
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Affiliation(s)
- Stergios A Polyzos
- First Laboratory of Pharmacology, School of Medicine, Aristotle University of Thessaloniki, Thessaloniki, Greece.
| | | | - Tim Cundy
- Faculty of Medical & Health Sciences, University of Auckland, Auckland, New Zealand
| | - Marina Kita
- Department of Endocrinology, Ippokration General Hospital, Thessaloniki, Greece
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3
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Jovanovic M, Marini JC. Update on the Genetics of Osteogenesis Imperfecta. Calcif Tissue Int 2024; 115:891-914. [PMID: 39127989 PMCID: PMC11607015 DOI: 10.1007/s00223-024-01266-5] [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: 05/31/2024] [Accepted: 07/22/2024] [Indexed: 08/12/2024]
Abstract
Osteogenesis imperfecta (OI) is a heterogeneous heritable skeletal dysplasia characterized by bone fragility and deformity, growth deficiency, and other secondary connective tissue defects. OI is now understood as a collagen-related disorder caused by defects of genes whose protein products interact with collagen for folding, post-translational modification, processing and trafficking, affecting bone mineralization and osteoblast differentiation. This review provides the latest updates on genetics of OI, including new developments in both dominant and rare OI forms, as well as the signaling pathways involved in OI pathophysiology. There is a special emphasis on discoveries of recessive mutations in TENT5A, MESD, KDELR2 and CCDC134 whose causality of OI types XIX, XX, XXI and XXI, respectively, is now established and expends the complexity of mechanisms underlying OI to overlap LRP5/6 and MAPK/ERK pathways. We also review in detail new discoveries connecting the known OI types to each other, which may underlie an eventual understanding of a final common pathway in OI cellular and bone biology.
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Affiliation(s)
- Milena Jovanovic
- Section on Heritable Disorders of Bone and Extracellular Matrix, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, USA
- Section on Adolescent Bone and Body Composition, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, USA
| | - Joan C Marini
- Section on Heritable Disorders of Bone and Extracellular Matrix, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, USA.
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Komori T. Regulation of Skeletal Development and Maintenance by Runx2 and Sp7. Int J Mol Sci 2024; 25:10102. [PMID: 39337587 PMCID: PMC11432631 DOI: 10.3390/ijms251810102] [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: 07/29/2024] [Revised: 09/16/2024] [Accepted: 09/18/2024] [Indexed: 09/30/2024] Open
Abstract
Runx2 (runt related transcription factor 2) and Sp7 (Sp7 transcription factor 7) are crucial transcription factors for bone development. The cotranscription factor Cbfb (core binding factor beta), which enhances the DNA-binding capacity of Runx2 and stabilizes the Runx2 protein, is necessary for bone development. Runx2 is essential for chondrocyte maturation, and Sp7 is partly involved. Runx2 induces the commitment of multipotent mesenchymal cells to osteoblast lineage cells and enhances the proliferation of osteoprogenitors. Reciprocal regulation between Runx2 and the Hedgehog, fibroblast growth factor (Fgf), Wnt, and parathyroid hormone-like hormone (Pthlh) signaling pathways and Dlx5 (distal-less homeobox 5) plays an important role in these processes. The induction of Fgfr2 (Fgf receptor 2) and Fgfr3 expression by Runx2 is important for the proliferation of osteoblast lineage cells. Runx2 induces Sp7 expression, and Runx2+ osteoprogenitors become Runx2+Sp7+ preosteoblasts. Sp7 induces the differentiation of preosteoblasts into osteoblasts without enhancing their proliferation. In osteoblasts, Runx2 is required for bone formation by inducing the expression of major bone matrix protein genes, including Col1a1 (collagen type I alpha 1), Col1a2, Spp1 (secreted phosphoprotein 1), Ibsp (integrin binding sialoprotein), and Bglap (bone gamma carboxyglutamate protein)/Bglap2. Bglap/Bglap2 (osteocalcin) regulates the alignment of apatite crystals parallel to collagen fibrils but does not function as a hormone that regulates glucose metabolism, testosterone synthesis, and muscle mass. Sp7 is also involved in Co1a1 expression and regulates osteoblast/osteocyte process formation, which is necessary for the survival of osteocytes and the prevention of cortical porosity. SP7 mutations cause osteogenesis imperfecta in rare cases. Runx2 is an important pathogenic factor, while Runx1, Runx3, and Cbfb are protective factors in osteoarthritis development.
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Affiliation(s)
- Toshihisa Komori
- Department of Molecular Tumor Biology, Nagasaki University Graduate School of Biomedical Sciences, 1-7-1 Sakamoto, Nagasaki 852-8588, Japan
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Wang X, Sun K, Xu Z, Chen Z, Wu W. Roles of SP/KLF transcription factors in odontoblast differentiation: From development to diseases. Oral Dis 2024; 30:3745-3760. [PMID: 38409677 DOI: 10.1111/odi.14904] [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: 11/27/2023] [Revised: 01/24/2024] [Accepted: 02/08/2024] [Indexed: 02/28/2024]
Abstract
OBJECTIVES A zinc-finger transcription factor family comprising specificity proteins (SPs) and Krüppel-like factor proteins (KLFs) plays an important role in dentin development and regeneration. However, a systematic regulatory network involving SPs/KLFs in odontoblast differentiation has not yet been described. This review examined the expression patterns of SP/KLF gene family members and their current known functions and mechanisms in odontoblast differentiation, and discussed prospective research directions for further exploration of mechanisms involving the SP/KLF gene family in dentin development. MATERIALS AND METHODS Relevant literature on SP/KLF gene family members and dentin development was acquired from PubMed and Web of Science. RESULTS We discuss the expression patterns, functions, and related mechanisms of eight members of the SP/KLF gene family in dentin development and genetic disorders with dental problems. We also summarize current knowledge about their complementary or synergistic actions. Finally, we propose future research directions for investigating the mechanisms of dentin development. CONCLUSIONS The SP/KLF gene family plays a vital role in tooth development. Studying the complex complementary or synergistic interactions between SPs/KLFs is helpful for understanding the process of odontoblast differentiation. Applications of single-cell and spatial multi-omics may provide a more complete investigation of the mechanism involved in dentin development.
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Affiliation(s)
- Xuefei Wang
- Stomatology Hospital, School of Stomatology, Zhejiang University School of Medicine, Zhejiang Provincial Clinical Research Center for Oral Diseases, Key Laboratory of Oral Biomedical Research of Zhejiang Province, Cancer Center of Zhejiang University, Engineering Research Center of Oral Biomaterials and Devices of Zhejiang Province, Hangzhou, China
| | - Kaida Sun
- Stomatology Hospital, School of Stomatology, Zhejiang University School of Medicine, Zhejiang Provincial Clinical Research Center for Oral Diseases, Key Laboratory of Oral Biomedical Research of Zhejiang Province, Cancer Center of Zhejiang University, Engineering Research Center of Oral Biomaterials and Devices of Zhejiang Province, Hangzhou, China
| | - Zekai Xu
- Stomatology Hospital, School of Stomatology, Zhejiang University School of Medicine, Zhejiang Provincial Clinical Research Center for Oral Diseases, Key Laboratory of Oral Biomedical Research of Zhejiang Province, Cancer Center of Zhejiang University, Engineering Research Center of Oral Biomaterials and Devices of Zhejiang Province, Hangzhou, China
| | - Zhuo Chen
- Stomatology Hospital, School of Stomatology, Zhejiang University School of Medicine, Zhejiang Provincial Clinical Research Center for Oral Diseases, Key Laboratory of Oral Biomedical Research of Zhejiang Province, Cancer Center of Zhejiang University, Engineering Research Center of Oral Biomaterials and Devices of Zhejiang Province, Hangzhou, China
| | - Wenzhi Wu
- Stomatology Hospital, School of Stomatology, Zhejiang University School of Medicine, Zhejiang Provincial Clinical Research Center for Oral Diseases, Key Laboratory of Oral Biomedical Research of Zhejiang Province, Cancer Center of Zhejiang University, Engineering Research Center of Oral Biomaterials and Devices of Zhejiang Province, Hangzhou, China
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Valea A, Nistor C, Ciobica ML, Sima OC, Carsote M. Endocrine Petrified Ear: Associated Endocrine Conditions in Auricular Calcification/Ossification (A Sample-Focused Analysis). Diagnostics (Basel) 2024; 14:1303. [PMID: 38928718 PMCID: PMC11202653 DOI: 10.3390/diagnostics14121303] [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: 04/30/2024] [Revised: 06/13/2024] [Accepted: 06/13/2024] [Indexed: 06/28/2024] Open
Abstract
Petrified ear (PE), an exceptional entity, stands for the calcification ± ossification of auricular cartilage (CAC/OAC); its pathogenic traits are still an open matter. Endocrine panel represents one of the most important; yet, no standard protocol of assessments is available. Our objective was to highlight most recent PE data and associated endocrine (versus non-endocrine) ailments in terms of presentation, imagery tools, hormonal assessments, biopsy, outcome, pathogenic features. This was a comprehensive review via PubMed search (January 2000-March 2024). A total of 75 PE subjects included: 46 case reports/series (N = 49) and two imagery-based retrospective studies (N = 26) with CAC/OAC prevalence of 7-23% (N = 251) amid routine head/temporal bone CT scans. Endocrine PE (EPE): N = 23, male/female ratio = 10.5; average age = 56.78, ranges: 22-79; non-EPE cohort: N = 26; male/female ratio = 1.88, mean age = 49.44; ranges: 18-75 (+a single pediatric case).The longest post-diagnosis follow-up was of 6-7 years. The diagnosis of PE and endocrine anomalies was synchronous or not (time gap of 10-20 years). A novel case in point (calcified EPE amid autoimmune poly-endocrine syndrome type 2 with a 10-year post-diagnosis documented follow-up) was introduced. We re-analyzed EPE and re-classified another five subjects as such. Hence, the final EPE cohort (N = 50) showed: adrenal insufficiency was the most frequent endocrine condition (36%) followed by hypopituitarism (22%) and hypothyroidism (18%); 39% of the patients with adrenal failure had Addison's disease; primary type represented 72% of all cases with hypothyroidism; an endocrine autoimmune (any type) component was diagnosed in 18%. We propose the term of "endocrine petrified ear" and a workflow algorithm to assess the potential hormonal/metabolic background in PE.
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Affiliation(s)
- Ana Valea
- Department of Endocrinology, “Iuliu Hatieganu” University of Medicine and Pharmacy, 400012 Cluj-Napoca, Romania;
- Clinical County Hospital, 400347 Cluj-Napoca, Romania
| | - Claudiu Nistor
- Department 4-Cardio-Thoracic Pathology, Thoracic Surgery II Discipline, “Carol Davila” University of Medicine and Pharmacy, 020021 Bucharest, Romania
- “Dr. Carol Davila” Central Military Emergency University Hospital, 010242 Bucharest, Romania;
| | - Mihai-Lucian Ciobica
- “Dr. Carol Davila” Central Military Emergency University Hospital, 010242 Bucharest, Romania;
- Department of Internal Medicine and Gastroenterology, “Carol Davila” University of Medicine and Pharmacy, 020021 Bucharest, Romania
| | - Oana-Claudia Sima
- PhD Doctoral School, “Carol Davila” University of Medicine and Pharmacy, 020021 Bucharest, Romania;
- “C.I. Parhon” National Institute of Endocrinology, 011683 Bucharest, Romania;
| | - Mara Carsote
- “C.I. Parhon” National Institute of Endocrinology, 011683 Bucharest, Romania;
- Department of Endocrinology, “Carol Davila” University of Medicine and Pharmacy, 020021 Bucharest, Romania
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Al-Mutairi DA, Jarragh AA, Alsabah BH, Wein MN, Mohammed W, Alkharafi L. A homozygous SP7/OSX mutation causes osteogenesis and dentinogenesis imperfecta with craniofacial anomalies. JBMR Plus 2024; 8:ziae026. [PMID: 38562913 PMCID: PMC10984723 DOI: 10.1093/jbmrpl/ziae026] [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: 11/28/2023] [Revised: 02/15/2024] [Accepted: 02/20/2024] [Indexed: 04/04/2024] Open
Abstract
Osteogenesis imperfecta (OI) is a heterogeneous spectrum of hereditary genetic disorders that cause bone fragility, through various quantitative and qualitative defects of type 1 collagen, a triple helix composed of two α1 and one α2 chains encoded by COL1A1 and COL1A2, respectively. The main extra-skeletal manifestations of OI include blue sclerae, opalescent teeth, and hearing impairment. Moreover, multiple genes involved in osteoblast maturation and type 1 collagen biosynthesis are now known to cause recessive forms of OI. In this study a multiplex consanguineous family of two affected males with OI was recruited for genetic screening. To determine the causative, pathogenic variant(s), genomic DNA from two affected family members were analyzed using whole exome sequencing, autozygosity mapping, and then validated with Sanger sequencing. The analysis led to the mapping of a homozygous variant previously reported in SP7/OSX, a gene encoding for Osterix, a transcription factor that activates a repertoire of genes involved in osteoblast and osteocyte differentiation and function. The identified variant (c.946C > T; p.Arg316Cys) in exon 2 of SP7/OSX results in a pathogenic amino acid change in two affected male siblings and develops OI, dentinogenesis imperfecta, and craniofacial anomaly. On the basis of the findings of the present study, SP7/OSX:c. 946C > T is a rare homozygous variant causing OI with extra-skeletal features in inbred Arab populations.
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Affiliation(s)
- Dalal A Al-Mutairi
- Department of Pathology, Faculty of Medicine, Kuwait University, 13110 Kuwait City, Kuwait
| | - Ali A Jarragh
- Department of Surgery, Faculty of Medicine, Kuwait University, 13110 Kuwait City, Kuwait
| | - Basel H Alsabah
- Zain Specialized Hospital for Ear, Nose and Throat, 70030 Kuwait City, Kuwait
| | - Marc N Wein
- Endocrine Unit, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02114, United States
| | - Wasif Mohammed
- Department of Radiology, Al Sabah Hospital, 13041 Kuwait City, Kuwait
| | - Lateefa Alkharafi
- Cleft and Craniofacial Unit, Farwaniya Specialized Dental Center, Ministry of Health, 13001 Kuwait City, Kuwait
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Gauthier LW, Fontanges E, Chapurlat R, Collet C, Rossi M. Long-term follow-up of severe autosomal recessive SP7-related bone disorder. Bone 2024; 179:116953. [PMID: 37918503 DOI: 10.1016/j.bone.2023.116953] [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: 09/15/2023] [Revised: 10/24/2023] [Accepted: 10/30/2023] [Indexed: 11/04/2023]
Abstract
The SP7 gene encodes a zinc finger transcription factor (Osterix), which is a member of the Sp subfamily of sequence-specific DNA-binding proteins, playing an important role in osteoblast differentiation and maturation. SP7 pathogenic variants have been described in association with different allelic disorders. Monoallelic or biallelic SP7 variants cause Osteogenesis imperfecta type XII (OI12), a very rare condition characterized by recurrent fractures, skeletal deformities, undertubulation of long bones, hearing loss, no dentinogenesis imperfecta, and white sclerae. Monoallelic or biallelic SP7 variants may also cause sclerotic skeletal dysplasias (SSD), partially overlapping with Juvenile Paget's disease and craniodiaphyseal dysplasia, characterized by skull hyperostosis, long bones sclerosis, large ribs and clavicles, and possible recurrent fractures. Here, we report the long-term follow-up of an 85-year-old woman presenting with a complex bone disorder including features of either OI12 (bone fragility with multiple fractures, severe deformities and short stature) or SSD (striking skull hyperostosis with optic atrophy, very large ribs and clavicles and long bones sclerosis). Exome sequencing showed previously undescribed biallelic loss of function variants in the SP7 gene: NM_001173467.2(SP7): c.359_362del, p.(Asp120Valfs*11); NM_001173467.2(SP7): c.1163_1174delinsT, p.(Pro388Leufs*33). RT-qPCR confirmed a severely reduced SP7 transcription compared to controls. Our report provides new insights into the clinical and molecular features and long-term outcome of SP7-related bone disorders (SP7-BD), suggesting a continuum phenotypic spectrum characterized by bone fragility, undertubulation of long bones, scoliosis, and very heterogeneous bone mineral density ranging from osteoporosis to osteosclerosis.
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Affiliation(s)
- Lucas W Gauthier
- Clinical Genetics Unit, Reference Centre for Skeletal Dysplasias, Genetics Department, Hospices Civils de Lyon, Bron, France
| | - Elisabeth Fontanges
- Bone Disease and Rheumatology Department, Reference Centre for Fibrous Dysplasia, Hospices Civils de Lyon, France
| | - Roland Chapurlat
- Bone Disease and Rheumatology Department, Reference Centre for Fibrous Dysplasia, Hospices Civils de Lyon, France; INSERM UMR_S 1033, Claude Bernard Lyon 1 University, Edouard Herriot hospital, Lyon, France
| | - Corinne Collet
- Department of Genetics, Necker Hospital, Assistance Publique - Hôpitaux de Paris, Paris, France
| | - Massimiliano Rossi
- Clinical Genetics Unit, Reference Centre for Skeletal Dysplasias, Genetics Department, Hospices Civils de Lyon, Bron, France; INSERM U1028, CNRS UMR5292, Lyon Neuroscience Research Centre, GENDEV Team, Claude Bernard Lyon 1 University, Bron, France.
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9
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Wang JS, Tokavanich N, Wein MN. SP7: from Bone Development to Skeletal Disease. Curr Osteoporos Rep 2023; 21:241-252. [PMID: 36881265 PMCID: PMC10758296 DOI: 10.1007/s11914-023-00778-7] [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] [Accepted: 01/18/2023] [Indexed: 03/08/2023]
Abstract
PURPOSE OF REVIEW The purpose of this review is to summarize the different roles of the transcription factor SP7 in regulating bone formation and remodeling, discuss current studies in investigating the causal relationship between SP7 mutations and human skeletal disease, and highlight potential therapeutic treatments that targeting SP7 and the gene networks that it controls. RECENT FINDINGS Cell-type and stage-specific functions of SP7 have been identified during bone formation and remodeling. Normal bone development regulated by SP7 is strongly associated with human bone health. Dysfunction of SP7 results in common or rare skeletal diseases, including osteoporosis and osteogenesis imperfecta with different inheritance patterns. SP7-associated signaling pathways, SP7-dependent target genes, and epigenetic regulations of SP7 serve as new therapeutic targets in the treatment of skeletal disorders. This review addresses the importance of SP7-regulated bone development in studying bone health and skeletal disease. Recent advances in whole genome and exome sequencing, GWAS, multi-omics, and CRISPR-mediated activation and inhibition have provided the approaches to investigate the gene-regulatory networks controlled by SP7 in bone and the therapeutic targets to treat skeletal disease.
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Affiliation(s)
- Jialiang S Wang
- Endocrine Unit, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA.
| | - Nicha Tokavanich
- Endocrine Unit, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA
- Department of Developmental Biology, Harvard School of Dental Medicine, Boston, MA, USA
| | - Marc N Wein
- Endocrine Unit, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA
- Broad Institute of Harvard and MIT, Cambridge, MA, USA
- Harvard Stem Cell Institute, Cambridge, MA, USA
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10
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Hendrickx G, Boudin E, Steenackers E, Collet C, Mortier GR, Geneviève D, Van Hul W. A recessive form of craniodiaphyseal dysplasia caused by a homozygous missense variant in SP7/Osterix. Bone 2023; 167:116633. [PMID: 36436818 DOI: 10.1016/j.bone.2022.116633] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/05/2022] [Revised: 10/28/2022] [Accepted: 11/21/2022] [Indexed: 11/25/2022]
Affiliation(s)
- Gretl Hendrickx
- Department of Medical Genetics, Antwerp University Hospital and University of Antwerp, 2650 Edegem, Belgium; Laboratory for Skeletal Dysplasia Research, Department of Human Genetics, KU Leuven, Herestraat 49, 3000 Leuven, Belgium
| | - Eveline Boudin
- Department of Medical Genetics, Antwerp University Hospital and University of Antwerp, 2650 Edegem, Belgium
| | - Ellen Steenackers
- Department of Medical Genetics, Antwerp University Hospital and University of Antwerp, 2650 Edegem, Belgium
| | - Corinne Collet
- INSERM U1132 and Université de Paris, Reference Centre for Rare Bone Diseases, Hospital Robert Debré, F-75010 Paris, France
| | - Geert R Mortier
- Department of Medical Genetics, Antwerp University Hospital and University of Antwerp, 2650 Edegem, Belgium; Laboratory for Skeletal Dysplasia Research, Department of Human Genetics, KU Leuven, Herestraat 49, 3000 Leuven, Belgium; Center for Human Genetics, University Hospital Leuven, Leuven, Belgium
| | - David Geneviève
- Montpellier University and INSERM U1183, Montpellier, France; Competence Center for Bone Diseases, Clinical Genetics Unit, Montpellier University Hospital, Montpellier, France
| | - Wim Van Hul
- Department of Medical Genetics, Antwerp University Hospital and University of Antwerp, 2650 Edegem, Belgium.
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11
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Ludwig K, Ward LM, Khan N, Robinson ME, Miranda V, Bardai G, Moffatt P, Rauch F. Dominant osteogenesis imperfecta with low bone turnover caused by a heterozygous SP7 variant. Bone 2022; 160:116400. [PMID: 35367406 DOI: 10.1016/j.bone.2022.116400] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/04/2022] [Revised: 03/15/2022] [Accepted: 03/27/2022] [Indexed: 02/07/2023]
Abstract
Mutations in SP7 (encoding osterix) have been identified as a rare cause of recessive osteogenesis imperfecta ('OI type XII') and in one case of dominant juvenile Paget's disease. We present the first description of young adult siblings with OI due to a unique heterozygous mutation in SP7. The phenotype was characterized by fragility fractures (primarily of the long bone diaphyses), poor healing, scoliosis, and dental malocclusion. Both siblings had very low cortical volumetric bone mineral density on peripheral quantitative computed tomography of the radius (z-scores -6.6 and - 6.7 at the diaphysis), porous cortices, and thin cortices at the radial metaphysis. Histomorphometry demonstrated thin cortices and low bone turnover with reduced osteoblast function. Both siblings were heterozygous for a missense variant affecting a highly conserved zinc finger domain of osterix (c.1019A > C; p.Glu340Ala) on DNA sequencing. Co-transfection of plasmids carrying the SP7 mutation with DLX5 and a luciferase reporter demonstrated that this variant impacted gene function (reduced transcription co-activation compared to wild-type SP7). The low cortical density and cortical porosity seen in our patients are consistent with previous reports of individuals with SP7 mutations. However, the low bone turnover in our patients contrasts with the high turnover state seen in previously reported patients with SP7 mutations. This report indicates that dominant variants in SP7 can give rise to OI. The predominant feature, low cortical density, is common in patients with other SP7 mutations, however other features appear to depend on the specific variant.
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Affiliation(s)
- Karissa Ludwig
- Shriners Hospital for Children - Canada, Montreal, QC, Canada
| | - Leanne M Ward
- Children's Hospital of Eastern Ontario, Ottawa, ON, Canada
| | - Nasrin Khan
- Children's Hospital of Eastern Ontario, Ottawa, ON, Canada
| | | | - Valancy Miranda
- Shriners Hospital for Children - Canada, Montreal, QC, Canada
| | - Ghalib Bardai
- Shriners Hospital for Children - Canada, Montreal, QC, Canada
| | - Pierre Moffatt
- Shriners Hospital for Children - Canada, Montreal, QC, Canada
| | - Frank Rauch
- Shriners Hospital for Children - Canada, Montreal, QC, Canada.
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12
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Hojo H, Ohba S. Sp7 Action in the Skeleton: Its Mode of Action, Functions, and Relevance to Skeletal Diseases. Int J Mol Sci 2022; 23:5647. [PMID: 35628456 PMCID: PMC9143072 DOI: 10.3390/ijms23105647] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2022] [Revised: 05/14/2022] [Accepted: 05/16/2022] [Indexed: 02/01/2023] Open
Abstract
Osteoblast differentiation is a tightly regulated process in which key transcription factors (TFs) and their target genes constitute gene regulatory networks (GRNs) under the control of osteogenic signaling pathways. Among these TFs, Sp7 works as an osteoblast determinant critical for osteoblast differentiation. Following the identification of Sp7 and a large number of its functional studies, recent genome-scale analyses have made a major contribution to the identification of a "non-canonical" mode of Sp7 action as well as "canonical" ones. The analyses have not only confirmed known Sp7 targets but have also uncovered its additional targets and upstream factors. In addition, biochemical analyses have demonstrated that Sp7 actions are regulated by chemical modifications and protein-protein interaction with other transcriptional regulators. Sp7 is also involved in chondrocyte differentiation and osteocyte biology as well as postnatal bone metabolism. The critical role of SP7 in the skeleton is supported by its relevance to human skeletal diseases. This review aims to overview the Sp7 actions in skeletal development and maintenance, particularly focusing on recent advances in our understanding of how Sp7 functions in the skeleton under physiological and pathological conditions.
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Affiliation(s)
- Hironori Hojo
- Center for Disease Biology and Integrative Medicine, Graduate School of Medicine, The University of Tokyo, Tokyo 113-0033, Japan;
| | - Shinsuke Ohba
- Department of Cell Biology, Institute of Biomedical Sciences, Nagasaki University, Nagasaki 852-8588, Japan
- Department of Oral Anatomy and Developmental Biology, Osaka University Graduate School of Dentistry, Osaka 565-0871, Japan
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13
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Lui JC, Raimann A, Hojo H, Dong L, Roschger P, Kikani B, Wintergerst U, Fratzl-Zelman N, Jee YH, Haeusler G, Baron J. A neomorphic variant in SP7 alters sequence specificity and causes a high-turnover bone disorder. Nat Commun 2022; 13:700. [PMID: 35121733 PMCID: PMC8816926 DOI: 10.1038/s41467-022-28318-4] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2020] [Accepted: 01/20/2022] [Indexed: 12/14/2022] Open
Abstract
SP7/Osterix is a transcription factor critical for osteoblast maturation and bone formation. Homozygous loss-of-function mutations in SP7 cause osteogenesis imperfecta type XII, but neomorphic (gain-of-new-function) mutations of SP7 have not been reported in humans. Here we describe a de novo dominant neomorphic missense variant (c.926 C > G:p.S309W) in SP7 in a patient with craniosynostosis, cranial hyperostosis, and long bone fragility. Histomorphometry shows increased osteoblasts but decreased bone mineralization. Mice with the corresponding variant also show a complex skeletal phenotype distinct from that of Sp7-null mice. The mutation alters the binding specificity of SP7 from AT-rich motifs to a GC-consensus sequence (typical of other SP family members) and produces an aberrant gene expression profile, including increased expression of Col1a1 and endogenous Sp7, but decreased expression of genes involved in matrix mineralization. Our study identifies a pathogenic mechanism in which a mutation in a transcription factor shifts DNA binding specificity and provides important in vivo evidence that the affinity of SP7 for AT-rich motifs, unique among SP proteins, is critical for normal osteoblast differentiation.
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Affiliation(s)
- Julian C Lui
- Section on Growth and Development, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, USA.
| | - Adalbert Raimann
- Department of Pediatrics and Adolescent Medicine, Division of Pediatric Pulmonology, Allergology and Endocrinology, Medical University of Vienna, Vienna, Austria
- Vienna Bone and Growth Center, Vienna, Austria
| | - Hironori Hojo
- Center for Disease and Integrative Medicine, University of Tokyo, Tokyo, Japan
| | - Lijin Dong
- Genetic Engineering Core, National Eye Institute, National Institute of Health, Bethesda, MD, USA
| | - Paul Roschger
- Ludwig Boltzmann Institute of Osteology at the Hanusch Hospital of OEGK and AUVA Trauma Centre Meidling, 1st Medical Department, Hanusch Hospital, Vienna, Austria
| | - Bijal Kikani
- Section on Growth and Development, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, USA
| | - Uwe Wintergerst
- Department of Pediatrics, Hospital of Braunau, Braunau, Austria
| | - Nadja Fratzl-Zelman
- Vienna Bone and Growth Center, Vienna, Austria
- Ludwig Boltzmann Institute of Osteology at the Hanusch Hospital of OEGK and AUVA Trauma Centre Meidling, 1st Medical Department, Hanusch Hospital, Vienna, Austria
| | - Youn Hee Jee
- Section on Growth and Development, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, USA
| | - Gabriele Haeusler
- Department of Pediatrics and Adolescent Medicine, Division of Pediatric Pulmonology, Allergology and Endocrinology, Medical University of Vienna, Vienna, Austria
- Vienna Bone and Growth Center, Vienna, Austria
| | - Jeffrey Baron
- Section on Growth and Development, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, USA
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Rauner M, Foessl I, Formosa MM, Kague E, Prijatelj V, Lopez NA, Banerjee B, Bergen D, Busse B, Calado Â, Douni E, Gabet Y, Giralt NG, Grinberg D, Lovsin NM, Solan XN, Ostanek B, Pavlos NJ, Rivadeneira F, Soldatovic I, van de Peppel J, van der Eerden B, van Hul W, Balcells S, Marc J, Reppe S, Søe K, Karasik D. Perspective of the GEMSTONE Consortium on Current and Future Approaches to Functional Validation for Skeletal Genetic Disease Using Cellular, Molecular and Animal-Modeling Techniques. Front Endocrinol (Lausanne) 2021; 12:731217. [PMID: 34938269 PMCID: PMC8686830 DOI: 10.3389/fendo.2021.731217] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/26/2021] [Accepted: 09/30/2021] [Indexed: 12/26/2022] Open
Abstract
The availability of large human datasets for genome-wide association studies (GWAS) and the advancement of sequencing technologies have boosted the identification of genetic variants in complex and rare diseases in the skeletal field. Yet, interpreting results from human association studies remains a challenge. To bridge the gap between genetic association and causality, a systematic functional investigation is necessary. Multiple unknowns exist for putative causal genes, including cellular localization of the molecular function. Intermediate traits ("endophenotypes"), e.g. molecular quantitative trait loci (molQTLs), are needed to identify mechanisms of underlying associations. Furthermore, index variants often reside in non-coding regions of the genome, therefore challenging for interpretation. Knowledge of non-coding variance (e.g. ncRNAs), repetitive sequences, and regulatory interactions between enhancers and their target genes is central for understanding causal genes in skeletal conditions. Animal models with deep skeletal phenotyping and cell culture models have already facilitated fine mapping of some association signals, elucidated gene mechanisms, and revealed disease-relevant biology. However, to accelerate research towards bridging the current gap between association and causality in skeletal diseases, alternative in vivo platforms need to be used and developed in parallel with the current -omics and traditional in vivo resources. Therefore, we argue that as a field we need to establish resource-sharing standards to collectively address complex research questions. These standards will promote data integration from various -omics technologies and functional dissection of human complex traits. In this mission statement, we review the current available resources and as a group propose a consensus to facilitate resource sharing using existing and future resources. Such coordination efforts will maximize the acquisition of knowledge from different approaches and thus reduce redundancy and duplication of resources. These measures will help to understand the pathogenesis of osteoporosis and other skeletal diseases towards defining new and more efficient therapeutic targets.
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Affiliation(s)
- Martina Rauner
- Department of Medicine III, Faculty of Medicine, Technische Universität Dresden, Dresden, Germany
- University Hospital Carl Gustav Carus, Dresden, Germany
| | - Ines Foessl
- Department of Internal Medicine, Division of Endocrinology and Diabetology, Endocrine Lab Platform, Medical University of Graz, Graz, Austria
| | - Melissa M. Formosa
- Department of Applied Biomedical Science, Faculty of Health Sciences, University of Malta, Msida, Malta
- Centre for Molecular Medicine and Biobanking, University of Malta, Msida, Malta
| | - Erika Kague
- School of Physiology, Pharmacology, and Neuroscience, Faculty of Life Sciences, University of Bristol, Bristol, United Kingdom
| | - Vid Prijatelj
- Department of Oral and Maxillofacial Surgery, Erasmus MC, University Medical Center Rotterdam, Rotterdam, Netherlands
- Department of Internal Medicine, Erasmus MC, University Medical Center Rotterdam, Rotterdam, Netherlands
- The Generation R Study, Erasmus MC, University Medical Center Rotterdam, Rotterdam, Netherlands
| | - Nerea Alonso Lopez
- Rheumatology and Bone Disease Unit, CGEM, Institute of Genetics and Cancer (IGC), Edinburgh, United Kingdom
| | - Bodhisattwa Banerjee
- Musculoskeletal Genetics Laboratory, Azrieli Faculty of Medicine, Bar-Ilan University, Safed, Israel
| | - Dylan Bergen
- School of Physiology, Pharmacology, and Neuroscience, Faculty of Life Sciences, University of Bristol, Bristol, United Kingdom
- Musculoskeletal Research Unit, Translational Health Sciences, Bristol Medical School, Faculty of Health Sciences, University of Bristol, Bristol, United Kingdom
| | - Björn Busse
- Department of Osteology and Biomechanics, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Ângelo Calado
- Instituto de Medicina Molecular João Lobo Antunes, Faculdade de Medicina, Universidade de Lisboa, Centro Académico de Medicina de Lisboa, Lisbon, Portugal
| | - Eleni Douni
- Department of Biotechnology, Agricultural University of Athens, Athens, Greece
- Institute for Bioinnovation, B.S.R.C. “Alexander Fleming”, Vari, Greece
| | - Yankel Gabet
- Department of Anatomy & Anthropology, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Natalia García Giralt
- Musculoskeletal Research Group, IMIM (Hospital del Mar Medical Research Institute), Centro de Investigación Biomédica en Red en Fragilidad y Envejecimiento Saludable (CIBERFES), ISCIII, Barcelona, Spain
| | - Daniel Grinberg
- Department of Genetics, Microbiology and Statistics, Faculty of Biology, Universitat de Barcelona, CIBERER, IBUB, IRSJD, Barcelona, Spain
| | - Nika M. Lovsin
- Department of Clinical Biochemistry, Faculty of Pharmacy, University of Ljubljana, Ljubljana, Slovenia
| | - Xavier Nogues Solan
- Musculoskeletal Research Group, IMIM (Hospital del Mar Medical Research Institute), Centro de Investigación Biomédica en Red en Fragilidad y Envejecimiento Saludable (CIBERFES), ISCIII, Barcelona, Spain
| | - Barbara Ostanek
- Department of Clinical Biochemistry, Faculty of Pharmacy, University of Ljubljana, Ljubljana, Slovenia
| | - Nathan J. Pavlos
- Bone Biology & Disease Laboratory, School of Biomedical Sciences, The University of Western Australia, Nedlands, WA, Australia
| | | | - Ivan Soldatovic
- Institute of Medical Statistics and Informatic, Faculty of Medicine, University of Belgrade, Belgrade, Serbia
| | - Jeroen van de Peppel
- Department of Internal Medicine, Erasmus MC, University Medical Center Rotterdam, Rotterdam, Netherlands
| | - Bram van der Eerden
- Department of Internal Medicine, Erasmus MC, University Medical Center Rotterdam, Rotterdam, Netherlands
| | - Wim van Hul
- Department of Medical Genetics, University of Antwerp, Antwerp, Belgium
| | - Susanna Balcells
- Department of Genetics, Microbiology and Statistics, Faculty of Biology, Universitat de Barcelona, CIBERER, IBUB, IRSJD, Barcelona, Spain
| | - Janja Marc
- Department of Clinical Biochemistry, Faculty of Pharmacy, University of Ljubljana, Ljubljana, Slovenia
| | - Sjur Reppe
- Unger-Vetlesen Institute, Lovisenberg Diaconal Hospital, Oslo, Norway
- Department of Plastic and Reconstructive Surgery, Oslo University Hospital, Oslo, Norway
- Department of Medical Biochemistry, Oslo University Hospital, Oslo, Norway
| | - Kent Søe
- Clinical Cell Biology, Department of Pathology, Odense University Hospital, Odense, Denmark
- Department of Clinical Research, University of Southern Denmark, Odense, Denmark
- Department of Molecular Medicine, University of Southern Denmark, Odense, Denmark
| | - David Karasik
- Azrieli Faculty of Medicine, Bar-Ilan University, Ramat Gan, Israel
- Marcus Research Institute, Hebrew SeniorLife, Boston, MA, United States
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15
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Prata AR, Saraiva J, Salgado M, Estanqueiro P. Juvenile Paget's Disease: Report of a successful treatment throughout the complete growth of a patient with a missense TNFRSF11B mutation. Joint Bone Spine 2021; 88:105243. [PMID: 34166796 DOI: 10.1016/j.jbspin.2021.105243] [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: 04/22/2021] [Accepted: 06/09/2021] [Indexed: 11/17/2022]
Abstract
INTRODUCTION Juvenile Paget's Disease (JPD) is an ultra-rare inherited osteopathy featuring markedly accelerated bone turnover. Several clinical characteristics have been reported, including bone deformities developing in childhood and hearing loss. CASE REPORT We report the case of a 2 ¾-year-old girl that presented with progressive bowing of both legs since the age of 2, lower limb pain and frequent falls with one consequent femur fracture. Plain radiographs revealed osteoectasia of the long bone's diaphysis, and laboratory tests showed extremely high serum total alkaline phosphatase levels. A missense mutation on the gene TNFRSF11B was identified in homozygosity, and the diagnosis of JPD was made. Treatment with bisphosphonates was initiated early and markedly improved lower limb bowing and pain. The patient reached adulthood with normal height, minor bone deformities, and no functional impairment. Despite the good skeletal symptom's response, bisphosphonates failed to prevent or improve sensorineural hearing loss. CONCLUSIONS In this clinical case, early treatment with bisphosphonates was effective for the treatment of JPD skeletal deformities. New therapeutic strategies need to be developed to better control the extraskeletal manifestations of JPD.
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Affiliation(s)
- Ana Rita Prata
- Rheumatology Unit, Hospitais da Universidade de Coimbra, Centro Hospitalar e Universitário de Coimbra, Praceta Professor Mota Pinto, 3004-561 Coimbra, Portugal.
| | - Jorge Saraiva
- Medical Genetics Unit, Hospital Pediátrico, Centro Hospitalar e Universitário de Coimbra, Avenida Afonso Romão, 3000-602 Coimbra, Portugal; University Clinic of Pediatrics, Faculty of Medicine, University of Coimbra, Rua Larga 2, 3000-370 Coimbra, Portugal; Clinical Academic Center of Coimbra, Rua Larga 2, 3000-370 Coimbra, Portugal
| | - Manuel Salgado
- Pediatric Rheumatology Unit, Hospital Pediátrico, Centro Hospitalar e Universitário de Coimbra, Avenida Afonso Romão, 3000-602 Coimbra, Portugal
| | - Paula Estanqueiro
- Pediatric Rheumatology Unit, Hospital Pediátrico, Centro Hospitalar e Universitário de Coimbra, Avenida Afonso Romão, 3000-602 Coimbra, Portugal
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16
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Abstract
PURPOSE OF REVIEW To provide an overview of the role of genes and loci that predispose to Paget's disease of bone and related disorders. RECENT FINDINGS Studies over the past ten years have seen major advances in knowledge on the role of genetic factors in Paget's disease of bone (PDB). Genome wide association studies have identified six loci that predispose to the disease whereas family based studies have identified a further eight genes that cause PDB. This brings the total number of genes and loci implicated in PDB to fourteen. Emerging evidence has shown that a number of these genes also predispose to multisystem proteinopathy syndromes where PDB is accompanied by neurodegeneration and myopathy due to the accumulation of abnormal protein aggregates, emphasising the importance of defects in autophagy in the pathogenesis of PDB. Genetic factors play a key role in the pathogenesis of PDB and the studies in this area have identified several genes previously not suspected to play a role in bone metabolism. Genetic testing coupled to targeted therapeutic intervention is being explored as a way of halting disease progression and improving outcome before irreversible skeletal damage has occurred.
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Affiliation(s)
- Navnit S Makaram
- Centre for Genomic and Experimental Medicine, Institute of Genetics and Cancer, University of Edinburgh, Edinburgh, EH4 2XU, UK
| | - Stuart H Ralston
- Centre for Genomic and Experimental Medicine, Institute of Genetics and Cancer, University of Edinburgh, Edinburgh, EH4 2XU, UK.
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