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Xue JY, Ikegawa S, Guo L. SLC4A2, another gene involved in acid-base balancing machinery of osteoclasts, causes osteopetrosis. Bone 2023; 167:116603. [PMID: 36343920 DOI: 10.1016/j.bone.2022.116603] [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: 08/24/2022] [Revised: 09/30/2022] [Accepted: 11/01/2022] [Indexed: 11/06/2022]
Abstract
SLC4A2 belongs to the Na+-independent solute carrier family 4 (SLC4) of anion exchangers, which regulate electroneutral exchange of Cl- for HCO3- and mediate intra- and extra-cellular pH, chloride concentration and cell volume. Slc4a2 also participates in gastric acid secretion, spermatogenesis and osteoclastogenesis. During osteoclast differentiation, Slc4a2 is exclusively expressed at the contra-lacunar membrane and is up-regulated with osteoclast maturation. Bi-allelic Slc4a2 loss-of-function mutations have been known to cause osteopetrosis in mice and cattle, but not in human. Recently, we have identified bi-allelic pathogenic variants in SLC4A2 in a patient affected by osteopetrosis with severe renal insufficiency, suggesting SLC4A2 deficiency causes a new type of autosomal recessive osteopetrosis (osteopetrosis, Ikegawa type). In this article, we review the advances in exploring the multiple functions of SLC4A2 with emphasis on its roles in osteoclast. Our review would contribute to understanding of the phenotypic spectrum and the pathomechanism of SLC4A2-associated osteopetrosis.
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Affiliation(s)
- Jing-Yi Xue
- Shaanxi Institute for Pediatric Diseases, Xi'an Children's Hospital, Affiliated Children's Hospital of Xi'an Jiaotong University, Xi'an 710082, China
| | - Shiro Ikegawa
- Laboratory for Bone and Joint Diseases, RIKEN Center for Integrative Medical Sciences, Tokyo 108-8639, Japan
| | - Long Guo
- Shaanxi Institute for Pediatric Diseases, Xi'an Children's Hospital, Affiliated Children's Hospital of Xi'an Jiaotong University, Xi'an 710082, China; Department of Laboratory Animal Science, School of Basic Medical Sciences, Xi'an Jiaotong University, Xi'an 710061, China.
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Turan S. Osteopetrosis: Gene-based nosology and significance Dysosteosclerosis. Bone 2023; 167:116615. [PMID: 36402365 DOI: 10.1016/j.bone.2022.116615] [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: 07/03/2022] [Revised: 11/09/2022] [Accepted: 11/12/2022] [Indexed: 11/18/2022]
Abstract
Dysosteosclerosis (DSS) refers to skeletal dysplasias that radiographically feature focal appendicular osteosclerosis with variable platyspondyly. Genetic heterogeneity is increasingly reported for the DSS phenotype and now involves mutations of SLC29A3, TNFRSF11A, TCIRG1, LRRK1, and CSF1R. Typical radiological findings are widened radiolucent long bones with thin cortices yet dense irregular metaphyses, flattened vertebral bodies, dense ribs, and multiple fractures. However, the radiographic features of DSS evolve, and the metaphyseal and/or appendicular osteosclerosis variably fades with increasing patient age, likely due to some residual osteoclast function. Fractures are the principal presentation of DSS, and may even occur in infancy with SLC29A3-associated DSS. Cranial base sclerosis can lead to cranial nerve palsies such as optic atrophy, and may be the initial presentation, though not observed with SLC29A3-associated DSS. Gene-specific extra-skeletal features can be the main complication in some forms of DSS such as CSF1R- associated DSS. Further genetic heterogeneity is likely, especially for X-linked recessive DSS and cases currently with an unknown genetic defect. Distinguishing DSS can be challenging due to variable clinical and radiological features and an evolving phenotype. However, defining the DSS phenotype is important for predicting complications, prognosis, and instituting appropriate health surveillance and treatment.
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Affiliation(s)
- Serap Turan
- Pediatric Endocrinology and Diabetes, Marmara University School of Medicine, Istanbul, Turkey.
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Abstract
Osteopetrosis (OPT) is a rare inherited bone disease characterized by a bone resorption defect, due to osteoclast malfunction (in osteoclast-rich, oc-rich, OPT forms) or absence (in oc-poor OPT forms). This causes severe clinical abnormalities, including increased bone density, lack of bone marrow cavity, stunted growth, macrocephaly, progressive deafness, blindness, hepatosplenomegaly, and severe anemia. The oc-poor subtype of OPT is ultra-rare in humans. It is caused by mutations in either the tumor necrosis factor ligand superfamily member 11 (TNFSF11) gene, encoding RANKL (Receptor Activator of Nuclear factor-kappa B [NF-κB] Ligand) which is expressed on cells of mesenchymal origin and lymphocytes, or the TNFRSF member 11A (TNFRSF11A) gene, encoding the RANKL functional receptor RANK which is expressed on cells of myeloid lineage including osteoclasts. Clinical presentation is usually severe with onset in early infancy or in fetal life, although as more patients are reported, expressivity is variable. Phenotypic variability of RANK-deficient OPT sometimes includes hypogammaglobulinemia or radiological features of dysosteosclerosis. Disease progression is somewhat slower in RANKL-deficient OPT than in other 'malignant' subtypes of OPT. While both RANKL and RANK are essential for normal bone turnover, hematopoietic stem cell transplantation (HSCT) is the treatment of choice only for patients with the RANK-deficient form of oc-poor OPT. So far, there is no cure for RANKL-deficient OPT.
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Affiliation(s)
- Cristina Sobacchi
- CNR-IRGB, Milan Unit, via Fantoli 16/15, 20138 Milan, Italy; Humanitas Research Hospital, via Manzoni 56, 20089 Rozzano, MI, Italy.
| | - Mario Abinun
- Paediatric Haematopoietic Stem Cell Transplant Unit, Great North Children's Hospital, Royal Victoria Infirmary, Queen Victoria Road, Newcastle upon Tyne NE1 4LP, UK; Translational and Clinical Research Institute, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne NE2 4HH, UK
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Turan S, Mumm S, Alavanda C, Kaygusuz BS, Gurpinar Tosun B, Arman A, Huskey M, Guran T, Duan S, Bereket A, Whyte MP. Dysosteosclerosis: Clinical and Radiological Evolution Reflecting Genetic Heterogeneity. JBMR Plus 2022; 6:e10663. [PMID: 35991533 PMCID: PMC9382861 DOI: 10.1002/jbm4.10663] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/29/2022] [Accepted: 06/27/2022] [Indexed: 11/12/2022] Open
Affiliation(s)
- Serap Turan
- Pediatric Endocrinology and Diabetes Marmara University Faculty of Medicine Istanbul Turkey
| | - Steven Mumm
- Division of Bone and Mineral Diseases, Department of Internal Medicine Washington University School of Medicine; St Louis Missouri USA
- Center for Metabolic Bone Disease and Molecular Research Shriners Hospitals for Children – St. Louis St. Louis Missouri USA
| | - Ceren Alavanda
- Medical Genetics Marmara University Faculty of Medicine Istanbul Turkey
| | - Betul Sare Kaygusuz
- Pediatric Endocrinology and Diabetes Marmara University Faculty of Medicine Istanbul Turkey
| | - Busra Gurpinar Tosun
- Pediatric Endocrinology and Diabetes Marmara University Faculty of Medicine Istanbul Turkey
| | - Ahmet Arman
- Medical Genetics Marmara University Faculty of Medicine Istanbul Turkey
| | - Margaret Huskey
- Division of Bone and Mineral Diseases, Department of Internal Medicine Washington University School of Medicine; St Louis Missouri USA
| | - Tulay Guran
- Pediatric Endocrinology and Diabetes Marmara University Faculty of Medicine Istanbul Turkey
| | - Shenghui Duan
- Division of Bone and Mineral Diseases, Department of Internal Medicine Washington University School of Medicine; St Louis Missouri USA
| | - Abdullah Bereket
- Pediatric Endocrinology and Diabetes Marmara University Faculty of Medicine Istanbul Turkey
| | - Michael P. Whyte
- Division of Bone and Mineral Diseases, Department of Internal Medicine Washington University School of Medicine; St Louis Missouri USA
- Center for Metabolic Bone Disease and Molecular Research Shriners Hospitals for Children – St. Louis St. Louis Missouri USA
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Kırkgöz T, Özkan B, Hazan F, Acar S, Nalbantoğlu Ö, Özkaya B, Kulalı MA, Gürsoy S, Ikegawa S, Guo L. A Null Mutation of TNFRSF11A Causes Dysosteosclerosis, Not Osteopetrosis. Front Genet 2022; 13:938814. [PMID: 35812760 PMCID: PMC9263543 DOI: 10.3389/fgene.2022.938814] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2022] [Accepted: 06/06/2022] [Indexed: 11/15/2022] Open
Abstract
Dysosteosclerosis (DOS) is a rare sclerosing bone dysplasia characterized by unique osteosclerosis of the long tubular bones and platyspondyly. DOS is inherited in an autosomal recessive manner and is genetically and clinically heterogeneous. To date, four individuals with DOS who have five different TNFRSF11A mutations have been reported. Based on their data, it is hypothesized that mutations producing aberrant mutant RANK proteins (missense or truncated or elongated) cause DOS, while null mutations lead to osteopetrosis, autosomal recessive 7 (OPTB7). Herein, we present the fifth case of TNFRSF11A-associated DOS with a novel homozygous frame-shift mutation (c.19_31del; p.[Arg7CysfsTer172]). The mutation is predicted to cause nonsense mutation-mediated mRNA decay (NMD) in all RANK isoform transcripts, resulting in totally null allele. Our findings suggest genotype-phenotype relationship in TNFRSF11A-associated OPTB7 and DOS remains unclear, and that the deficiency of TNFRSF11A functions might cause DOS, rather than osteopetrosis. More data are necessary to understand the phenotypic spectrum caused by TNFRSF11A mutations.
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Affiliation(s)
- Tarık Kırkgöz
- Division of Pediatric Endocrinology, Dr. Behçet Uz Children’s Education and Research Hospital, Izmir, Turkey
| | - Behzat Özkan
- Division of Pediatric Endocrinology, Dr. Behçet Uz Children’s Education and Research Hospital, Izmir, Turkey
| | - Filiz Hazan
- Department of Medical Genetics, Dr. Behçet Uz Children’s Education and Research Hospital, Izmir, Turkey
| | - Sezer Acar
- Division of Pediatric Endocrinology, Dr. Behçet Uz Children’s Education and Research Hospital, Izmir, Turkey
- *Correspondence: Sezer Acar, ; Long Guo,
| | - Özlem Nalbantoğlu
- Division of Pediatric Endocrinology, Dr. Behçet Uz Children’s Education and Research Hospital, Izmir, Turkey
| | - Beyhan Özkaya
- Division of Pediatric Endocrinology, Dr. Behçet Uz Children’s Education and Research Hospital, Izmir, Turkey
| | - Melike Ataseven Kulalı
- Division of Pediatric Genetics, School of Medicine, Afyon Kocatepe University, Afyonkarahisar, Turkey
| | - Semra Gürsoy
- Division of Pediatric Genetics, Dr. Behçet Uz Children’s Education and Research Hospital, Izmir, Turkey
| | - Shiro Ikegawa
- Laboratory for Bone and Joint Diseases, RIKEN Center for Integrative Medical Sciences, Tokyo, Japan
| | - Long Guo
- Laboratory for Bone and Joint Diseases, RIKEN Center for Integrative Medical Sciences, Tokyo, Japan
- *Correspondence: Sezer Acar, ; Long Guo,
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Uludağ Alkaya D, Akpınar E, Bilguvar K, Tüysüz B. Resolution of sclerotic lesions of dysosteosclerosis due to biallelic SLC29A3 variant in a Turkish girl. Am J Med Genet A 2021; 185:2271-2277. [PMID: 33837634 DOI: 10.1002/ajmg.a.62198] [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: 12/28/2020] [Revised: 02/13/2021] [Accepted: 03/19/2021] [Indexed: 11/09/2022]
Abstract
Dysosteosclerosis is a group of sclerosing bone dysplasia characterized by short stature, increased bone fragility, osteosclerosis, and platyspondyly. It is a genetically heterogeneous disorder caused by biallelic mutations in the SLC29A3, TNFRSF11A, TCIRG1, and CSF1R genes. To date, four dysosteosclerosis patients with SLC29A3 mutations have been reported. Here, we report biallelic SLC29A3 (c.303_320dupCTACTTTGAGAGCTACCT) variant in a three-year-old girl. She had large anterior fontanelle, fracture history, short stature, camptodactyly, elbow contracture, and melanocytic nevus. Initial skeletal radiographs revealed platyspondyly, dense vertebral endplates (sandwich appearance of the vertebral bodies), diffuse sclerosis of the peripheral side of the pelvic bones, sclerosis of metaphysis and diaphysis of the long bones, metaphyseal widening, and diaphyseal cortical thickening. Mild sclerosis was also present in the skull base, maxilla, rib, scapula, and phalanges. Notably, we observed that sandwich vertebrae appearance significantly resolved and sclerosis of ribs, scapula, pelvis, and long bone metaphysis regressed over a 2.5-year period. However, platyspondyly, metaphyseal widening, and diaphyseal cortical thickening persisted. In conclusion, this study demonstrates spontaneous resolution of osteosclerosis, which was not described previously in patients with dysosteosclerosis.
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Affiliation(s)
- Dilek Uludağ Alkaya
- Department of Pediatric Genetics, Cerrahpasa Medical School, Istanbul University-Cerrahpasa, Istanbul, Turkey
| | - Evren Akpınar
- Baltalimani Bone Diseases Training and Research Center, Departments of Orthopedics and Traumatology, University of Health Sciences Istanbul, Istanbul, Turkey
| | - Kaya Bilguvar
- Department of Neurosurgery, Program on Neurogenetics, Yale Medical School, Yale University, New Haven, Connecticut, USA
| | - Beyhan Tüysüz
- Department of Pediatric Genetics, Cerrahpasa Medical School, Istanbul University-Cerrahpasa, Istanbul, Turkey
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Taylor-Miller T, Sivaprakasam P, Smithson SF, Steward CG, Burren CP. Challenges in long-term control of hypercalcaemia with denosumab after haematopoietic stem cell transplantation for TNFRSF11A osteoclast-poor autosomal recessive osteopetrosis. Bone Rep 2020; 14:100738. [PMID: 33364264 PMCID: PMC7750151 DOI: 10.1016/j.bonr.2020.100738] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/20/2020] [Revised: 11/22/2020] [Accepted: 11/28/2020] [Indexed: 11/30/2022] Open
Abstract
Autosomal recessive osteopetrosis (ARO) is rare, involving increased bone density due to defective osteoclast differentiation or function, with several genetic subtypes. Case This child with compound heterozygous novel loss-of-function TNFRSF11A pathogenic variants causing osteoclast-poor ARO underwent haematopoietic stem cell transplantation (HSCT) aged 3.1 years and experienced episodic severe hypercalcaemia over 2.5 years. She initially presented aged 8 months with craniosynostosis and visual impairment and underwent surgery; no increased bone density evident on skull imaging nor variants in genes associated with craniosynostosis identified. She was subsequently referred for investigation of poor linear growth and low alkaline phosphatase. Clinical abnormalities included asymmetric pectus carinatum, thickened anterior tibia and wrists, and markedly delayed dentition. Skeletal survey revealed generalised osteosclerosis with undertubulation. Management She received haploidentical HSCT aged 3.1 years and developed hypercalcaemia (adjusted calcium 4.09mmol/L = 16.4mg/dL) Day 18 post-HSCT, unresponsive to hyperhydration and diuretics. Denosumab achieved normocalcaemia, which required 0.6mg/kg every 6 weeks long-term. The ensuing 2.75 years feature full donor engraftment, good HSCT graft function, skeletal remodelling with 2.5 years recurrent severe hypercalcaemia and nine fragility long bone fractures. Conclusion This case illustrates challenges of bone and calcium management in ultrarare TNFRSF11A-related OP-ARO. Craniosynostosis was an early feature, evident pre-sclerosis in osteopetrosis. Following HSCT, restoration of osteoclast activity in the context of elevated bone mass produced severe and prolonged (2.5 years) hypercalcaemia. Denosumab was effective medium-term, but required concurrent long duration (11 months) zoledronic acid to manage recurrent hypercalcaemia. Fragility fractures brought appreciable additional morbidity in the post-HSCT phase.
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Affiliation(s)
- Tashunka Taylor-Miller
- Department of Paediatric Endocrinology, Bristol Royal Hospital for Children, University Hospitals Bristol and Weston NHS Foundation Trust, Bristol, United Kingdom
| | - Ponni Sivaprakasam
- Paediatric Bone Marrow Transplant Service, Bristol Royal Hospital for Children, University Hospitals Bristol and Weston NHS Foundation Trust, Bristol, United Kingdom
| | - Sarah F Smithson
- Department of Clinical Genetics, St Michaels Hospital, University Hospitals Bristol and Weston NHS Foundation Trust, Bristol, United Kingdom.,Bristol Medical School: Translational Health Sciences, University of Bristol, Bristol, United Kingdom
| | - Colin G Steward
- Bristol Medical School: Translational Health Sciences, University of Bristol, Bristol, United Kingdom.,School of Cellular and Molecular Medicine, University of Bristol, Queens Road, Bristol BS8 1QU, United Kingdom
| | - Christine P Burren
- Department of Paediatric Endocrinology, Bristol Royal Hospital for Children, University Hospitals Bristol and Weston NHS Foundation Trust, Bristol, United Kingdom.,Bristol Medical School: Translational Health Sciences, University of Bristol, Bristol, United Kingdom
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