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Giambra M, Di Cristofori A, Conconi D, Marzorati M, Redaelli S, Zambuto M, Rocca A, Roumy L, Carrabba G, Lavitrano M, Roversi G, Giussani C, Bentivegna A. Insights into the Peritumoural Brain Zone of Glioblastoma: CDK4 and EXT2 May Be Potential Drivers of Malignancy. Int J Mol Sci 2023; 24. [PMID: 36769158 DOI: 10.3390/ijms24032835] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2022] [Revised: 01/20/2023] [Accepted: 01/30/2023] [Indexed: 02/05/2023] Open
Abstract
Despite the efforts made in recent decades, glioblastoma is still the deadliest primary brain cancer without cure. The potential role in tumour maintenance and progression of the peritumoural brain zone (PBZ), the apparently normal area surrounding the tumour, has emerged. Little is known about this area due to a lack of common definition and due to difficult sampling related to the functional role of peritumoural healthy brain. The aim of this work was to better characterize the PBZ and to identify genes that may have role in its malignant transformation. Starting from our previous study on the comparison of the genomic profiles of matched tumour core and PBZ biopsies, we selected CDK4 and EXT2 as putative malignant drivers of PBZ. The gene expression analysis confirmed their over-expression in PBZ, similarly to what happens in low-grade glioma and glioblastoma, and CDK4 high levels seem to negatively influence patient overall survival. The prognostic role of CDK4 and EXT2 was further confirmed by analysing the TCGA cohort and bioinformatics prediction on their gene networks and protein-protein interactions. These preliminary data constitute a good premise for future investigations on the possible role of CDK4 and EXT2 in the malignant transformation of PBZ.
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Ajmal M, Muhammad H, Nasir M, Shoaib M, Malik SA, Ullah I. Haploinsufficiency of EXT1 and Heparan Sulphate Deficiency Associated with Hereditary Multiple Exostoses in a Pakistani Family. Medicina (B Aires) 2022; 59. [PMID: 36676722 DOI: 10.3390/medicina59010100] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2022] [Revised: 12/26/2022] [Accepted: 12/28/2022] [Indexed: 01/04/2023] Open
Abstract
Background and Objectives: Hereditary multiple exostoses (HME) is a disease characterized by cartilage-capped bony protuberances at the site of growth plates of long bones. Functional mutations in the exostosin genes (EXT1 and EXT2) are reported to affect the hedgehog signalling pathways leading to multiple enchondromatosis. However, the exact role of each EXT protein in the regulation of heparan sulphate (HS) chain elongation is still an enigma. In this study, a Pakistani family with HME is investigated to find out the genetic basis of the disease. Materials and Methods: Genotyping of eight members of the family by amplifying microsatellite markers, tightly linked to the EXT1 and EXT2 genes. Results: The study revealed linkage of the HME family to the EXT1 locus 8q24.1. Sanger sequencing identified a heterozygous deletion (c.247Cdel) in exon 1 of EXT1, segregating with the disease phenotype in the family. In silico analysis predicted a shift in the frame causing an early stop codon (p.R83GfsX52). The predicted dwarf protein constituting 134 amino acids was functionally aberrant with a complete loss of the catalytic domain at the C-terminus. Interestingly, an alternative open reading frame 3 (ORF3) caused by the frame shift is predicted to encode a protein sequence, identical to the wild type and containing the catalytic domain, but lacking the first 100 amino acids of the wild-type EXT1 protein. Conclusion: Consequently, haploinsufficiency could be the cause of HME in the investigated family as the mutated copy of EXT1 is ineffective for EXT-1/2 complex formation. The predicted ORF3 protein could be of great significance in understanding several aspects of HME pathogenesis.
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Corsini S, Pedrini E, Patavino C, Gnoli M, Lanza M, Sangiorgi L. An Easy-to-Use Approach to Detect CNV From Targeted NGS Data: Identification of a Novel Pathogenic Variant in MO Disease. Front Endocrinol (Lausanne) 2022; 13:874126. [PMID: 35837302 PMCID: PMC9273874 DOI: 10.3389/fendo.2022.874126] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/11/2022] [Accepted: 05/25/2022] [Indexed: 11/17/2022] Open
Abstract
BACKGROUND Despite the new next-generation sequencing (NGS) molecular approaches implemented the genetic testing in clinical diagnosis, copy number variation (CNV) detection from NGS data remains difficult mainly in the absence of bioinformatics personnel (not always available among laboratory resources) and when using very small gene panels that do not meet commercial software criteria. Furthermore, not all large deletions/duplications can be detected with the Multiplex Ligation-dependent Probe Amplification (MLPA) technique due to both the limitations of the methodology and no kits available for the most of genes. AIM We propose our experience regarding the identification of a novel large deletion in the context of a rare skeletal disease, multiple osteochondromas (MO), using and validating a user-friendly approach based on NGS coverage data, which does not require any dedicated software or specialized personnel. METHODS The pipeline uses a simple algorithm comparing the normalized coverage of each amplicon with the mean normalized coverage of the same amplicon in a group of "wild-type" samples representing the baseline. It has been validated on 11 samples, previously analyzed by MLPA, and then applied on 20 patients with MO but negative for the presence of pathogenic variants in EXT1 or EXT2 genes. Sensitivity, specificity, and accuracy were evaluated. RESULTS All the 11 known CNVs (exon and multi-exon deletions) have been detected with a sensitivity of 97.5%. A novel EXT2 partial exonic deletion c. (744-122)-?_804+?del -out of the MLPA target regions- has been identified. The variant was confirmed by real-time quantitative Polymerase Chain Reaction (qPCR). CONCLUSION In addition to enhancing the variant detection rate in MO molecular diagnosis, this easy-to-use approach for CNV detection can be easily extended to many other diagnostic fields-especially in resource-limited settings or very small gene panels. Notably, it also allows partial-exon deletion detection.
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Yang M, Xie H, Xu B, Xiang Q, Wang H, Hu T, Liu S. Identification of a novel EXT2 frameshift mutation in a family with hereditary multiple exostoses by whole-exome sequencing. J Clin Lab Anal 2021; 35:e23968. [PMID: 34403521 PMCID: PMC8418499 DOI: 10.1002/jcla.23968] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2020] [Revised: 08/04/2021] [Accepted: 08/10/2021] [Indexed: 02/06/2023] Open
Abstract
BACKGROUND Hereditary multiple exostoses (HME), also referred to as multiple osteochondromas, is an autosomal dominant skeletal disease characterized by the development of multiple overgrown benign bony tumors capped by cartilage and is associated with bone deformity, joint limitation, and short stature. Mutations in exostosin glycosyltransferase (EXT)1 and EXT2 genes, which are located on chromosomes 8q24.1 and 11p13, contribute to the pathogenesis of HME. METHODS In the present study, a genetic analysis of a four-generation Chinese family with HME was conducted using whole-exome sequencing (WES), followed by validation using Sanger sequencing. RESULTS A novel heterozygous frameshift mutation in exon 5 of EXT2 (c.944dupT, p.Leu316fs) was identified in all affected individuals but was not detected in any unaffected individuals. This mutation results in a frameshift that introduces a premature termination codon at position 318 (p.Leu316fs) with the ability to produce a truncated EXT2 protein that lacks the last 433 amino acids at its C-terminal to indicate a defective exostosin domain and the absence of the glycosyltransferase family 64 domain, or to lead to the degradation of mRNAs by nonsense-mediated mRNA decay, which is critical for the function of EXT2. CONCLUSION Our results indicate that WES is effective in extending the EXT mutational spectra and is advantageous for genetic counseling and the subsequent prenatal diagnosis.
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Affiliation(s)
- Mei Yang
- Department of Obstetrics & Gynecology, West China Second University Hospital, Sichuan University, Chengdu, Sichuan, China.,Key Laboratory of Birth Defects and Related Diseases of Women and Children, Ministry of Education, Sichuan University, Chengdu, Sichuan, China
| | - Hanbing Xie
- Department of Obstetrics & Gynecology, West China Second University Hospital, Sichuan University, Chengdu, Sichuan, China.,Key Laboratory of Birth Defects and Related Diseases of Women and Children, Ministry of Education, Sichuan University, Chengdu, Sichuan, China
| | - Bocheng Xu
- Department of Obstetrics & Gynecology, West China Second University Hospital, Sichuan University, Chengdu, Sichuan, China.,Key Laboratory of Birth Defects and Related Diseases of Women and Children, Ministry of Education, Sichuan University, Chengdu, Sichuan, China
| | - Qinqin Xiang
- Department of Obstetrics & Gynecology, West China Second University Hospital, Sichuan University, Chengdu, Sichuan, China.,Key Laboratory of Birth Defects and Related Diseases of Women and Children, Ministry of Education, Sichuan University, Chengdu, Sichuan, China
| | - He Wang
- Department of Obstetrics & Gynecology, West China Second University Hospital, Sichuan University, Chengdu, Sichuan, China.,Key Laboratory of Birth Defects and Related Diseases of Women and Children, Ministry of Education, Sichuan University, Chengdu, Sichuan, China
| | - Ting Hu
- Department of Obstetrics & Gynecology, West China Second University Hospital, Sichuan University, Chengdu, Sichuan, China.,Key Laboratory of Birth Defects and Related Diseases of Women and Children, Ministry of Education, Sichuan University, Chengdu, Sichuan, China
| | - Shanling Liu
- Department of Obstetrics & Gynecology, West China Second University Hospital, Sichuan University, Chengdu, Sichuan, China.,Key Laboratory of Birth Defects and Related Diseases of Women and Children, Ministry of Education, Sichuan University, Chengdu, Sichuan, China
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Tong Y, Luo J, Zhang Y, Hong Z, Cao L, Chen X, Chen J, Bi Q. Novel Mutations in Chinese Patients with Multiple Osteochondromas Identified Using Whole Exome Sequencing. Genet Test Mol Biomarkers 2021; 25:361-367. [PMID: 34003695 DOI: 10.1089/gtmb.2020.0317] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Background: Multiple osteochondromas (MO) are an autosomal-dominant disease characterized by the growth of multiple cartilage-capped prominences in the growth plate region of the metaphysis in long and flat bones. Materials and Methods: To detect genetic mutations related to MO, a three-generation Chinese family with MO was evaluated using whole exome sequencing for mutation screening. The candidate pathogenic mutation was validated by Sanger sequencing. Results: A novel frameshift (NM_000401.3:c.1321del:p.Leu441TrpfsTer28) in exon 8 of the exotosin 2 (EXT2) gene was identified in two affected individuals. Codons 441 and 468 in the EXT2 gene are highly conserved among vertebrates as demonstrated by multiple sequence alignment. The c.1321 del C resulted in an amino acid change at codon 441, which generated a premature stop codon at position 468, causing complete loss of the glycosyltransferase domain. Conclusions: A novel frameshift mutation c.1321delC detected in the EXT2 gene may help in prenatal genetic screening and early diagnosis of MO.
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Affiliation(s)
- Yu Tong
- The Second Affiliated Hospital and Yuying Children's Hospital of Wenzhou Medical University, Wenzhou, Zhejiang, China.,Department of Orthopedic Surgery, People's Hospital of Hangzhou Medical College, Zhejiang Provincial People's Hospital, Hangzhou, Zhejiang, China
| | - Junchao Luo
- The Second Affiliated Hospital and Yuying Children's Hospital of Wenzhou Medical University, Wenzhou, Zhejiang, China
| | - Yin Zhang
- Graduate Department, Bengbu Medical College, Bengbu, China
| | - Zheping Hong
- Department of Orthopedic Surgery, People's Hospital of Hangzhou Medical College, Zhejiang Provincial People's Hospital, Hangzhou, Zhejiang, China
| | - Li Cao
- Department of Orthopedic Surgery, People's Hospital of Hangzhou Medical College, Zhejiang Provincial People's Hospital, Hangzhou, Zhejiang, China
| | - Xinji Chen
- Department of Orthopedic Surgery, People's Hospital of Hangzhou Medical College, Zhejiang Provincial People's Hospital, Hangzhou, Zhejiang, China
| | - Jihang Chen
- Department of Orthopedic Surgery, People's Hospital of Hangzhou Medical College, Zhejiang Provincial People's Hospital, Hangzhou, Zhejiang, China
| | - Qing Bi
- The Second Affiliated Hospital and Yuying Children's Hospital of Wenzhou Medical University, Wenzhou, Zhejiang, China.,Department of Orthopedic Surgery, People's Hospital of Hangzhou Medical College, Zhejiang Provincial People's Hospital, Hangzhou, Zhejiang, China
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Abstract
UNLABELLED We analyzed osteoporosis in 20 HME patients. According to the T-score of BMD, 30% and 67.5% of the patients fell in the range of osteopenia in the lumbar spine and femoral neck. Our results indicate HME patients have low bone mass. They do not have abnormal bone metabolism. INTRODUCTION There are few reports of osteoporosis in hereditary multiple exostoses (HME) patients. Therefore, the purpose of this study was to analyze osteoporosis in HME patients. METHODS This retrospective cohort study included 20 patients diagnosed with HME. Patients underwent bone mineral density (BMD) measurement of the lumbar spine (n = 20) and femoral neck (n = 40). Bone metabolic parameters, including serum osteocalcin and urinary cross-linked N-telopeptide of type 1 collagen (NTx), were analyzed in all subjects. EXT1 and EXT2 genes were sequenced using genomic DNA. We also examined the correlation between genotype and BMD Z-score and T-score. RESULTS The mean BMD values of the lumbar spine were 1.085 ± 0.116 g/cm2 (n = 11) in male and 1.108 ± 0.088 g/cm2 (n = 9) in female. The mean BMD values of the femoral neck area were 0.759 ± 0.125 g/cm2 (n = 22) in male and 0.749 ± 0.115 g/cm2 (n = 18) in female. Z-score of most HME patients show < 0, indicating that these patients tend to have low bone mass compared with the age-matched population. According to the T-score of BMD, 30% (6 of 20) and 67.5% (27 of 40) of the patients fell in the range of osteopenia in the lumbar spine and femoral neck areas, respectively. Serum osteocalcin and urinary NTx were in the normal range in most patients. There was no significant correlation between genotypes and Z-score. CONCLUSION HME patients have low bone mass, especially in the femoral neck area. They do not have abnormal bone metabolism, and there was no correlation between genotypes and Z-score.
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Affiliation(s)
- K Matsumoto
- Department of Orthopaedic Surgery, Gifu University, Graduate School of Medicine, 1-1, Yanagido, Gifu, 501-1194, Japan.
| | - H Ogawa
- Department of Orthopaedic Surgery, Gifu University, Graduate School of Medicine, 1-1, Yanagido, Gifu, 501-1194, Japan
| | - S Nozawa
- Department of Orthopaedic Surgery, Gifu University, Graduate School of Medicine, 1-1, Yanagido, Gifu, 501-1194, Japan
| | - H Akiyama
- Department of Orthopaedic Surgery, Gifu University, Graduate School of Medicine, 1-1, Yanagido, Gifu, 501-1194, Japan
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Liang C, Wang YJ, Wei YX, Dong Y, Zhang ZC. Identification of Novel EXT Mutations in Patients with Hereditary Multiple Exostoses Using Whole-Exome Sequencing. Orthop Surg 2020; 12:990-996. [PMID: 32293802 PMCID: PMC7307237 DOI: 10.1111/os.12660] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/11/2019] [Revised: 02/11/2020] [Accepted: 02/19/2020] [Indexed: 12/16/2022] Open
Abstract
Objective To find novel potential gene mutations other than EXT1 and EXT2 mutations, to expand the mutational spectrum of EXT and to explore the correlation between clinical outcome and genotype in patients with hereditary multiple exostoses (HME). Methods The study recruited seven families diagnosed with multiple osteochondromas (MO). Family histories and clinical information were collected in detail through comprehensive physical and image examination. Patients with deformities and functional limitations were classified as “severe” and the remaining without functional limitations were classified as “mild,” in accordance with previous study. Whole‐exome sequencing (WES) was performed on a total of 13 affected individuals, 1 available unaffected relative, and 10 healthy unrelated individuals. Sanger sequencing was used to validate the screened mutations. Finally, the structural change in protein caused by pathogenic mutations was analyzed using information from the relevant database online and we attempted to correlate clinical phenotype with genotype in patients with HME. Results Other than EXT1 and EXT2, no novel potential gene mutations were found through WES. We identified nine heterozygous mutations in EXT1 or EXT2. Of these mutations, four have not been reported previously. These are c.996delT in exon 2 of EXT1 (family 1), c.544C > T in exon 3 of EXT2 (family 2), c.1171C > T in exon 7 of EXT2 (family 5), and c.823–824delAA in exon 5 of EXT1 (family 7). The other five mutations have already been reported in previous works. It was surprising that we found two mutation sites, in exon 2 and exon 5, respectively, of EXT1 in 1 patient diagnosed with MO, when his father had two mutation sites, in exon 6 and exon 5, respectively, of EXT1 and EXT2 (family 4). In addition, 1 patient showed degeneration, while his father only exhibited slight symptoms (family 7). In our study, among 51 affected patients in seven families, the sex ratio (male vs female) was 58.9% (n = 30) vs 41.2% (n = 21). Male patients seemed to show more severe symptoms compared to females, but because the sample was small, we did not obtain statistically significance results. Conclusion Whole‐exome sequencing to screen pathogenic gene mutations was applied successfully. Although no third‐gene mutation associated with HME was found, a total of nine mutations across EXT1 and EXT2 were identified, four of which are novel. Our results expand the mutational spectrum of EXT and can be used in genetic counseling and prenatal diagnosis for patients with MO.
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Affiliation(s)
- Chao Liang
- Department of Orthopaedics, Shanghai Jiao Tong University Affiliated Sixth People's Hospital, Shanghai, China
| | - Yong-Jie Wang
- Department of Orthopaedics, Shanghai Jiao Tong University Affiliated Sixth People's Hospital, Shanghai, China
| | - Yu-Xuan Wei
- Department of Orthopaedics, National Cancer Center/National Clinical Research Center for Cancer/Cancer Hospital & Shenzhen Hospital, Chinese Academy of Sciences and Peking Union Medical College, Shenzhen, China
| | - Yang Dong
- Department of Orthopaedics, Shanghai Jiao Tong University Affiliated Sixth People's Hospital, Shanghai, China
| | - Zhi-Chang Zhang
- Department of Orthopaedics, Shanghai Jiao Tong University Affiliated Sixth People's Hospital, Shanghai, China
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Serra-Vinardell J, Roca-Ayats N, De-Ugarte L, Vilageliu L, Balcells S, Grinberg D. Bone development and remodeling in metabolic disorders. J Inherit Metab Dis 2020; 43:133-144. [PMID: 30942483 DOI: 10.1002/jimd.12097] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/04/2019] [Accepted: 03/29/2019] [Indexed: 02/01/2023]
Abstract
There are many metabolic disorders that present with bone phenotypes. In some cases, the pathological bone symptoms are the main features of the disease whereas in others they are a secondary characteristic. In general, the generation of the bone problems in these disorders is not well understood and the therapeutic options for them are scarce. Bone development occurs in the early stages of embryonic development where the bone formation, or osteogenesis, takes place. This osteogenesis can be produced through the direct transformation of the pre-existing mesenchymal cells into bone tissue (intramembranous ossification) or by the replacement of the cartilage by bone (endochondral ossification). In contrast, bone remodeling takes place during the bone's growth, after the bone development, and continues throughout the whole life. The remodeling involves the removal of mineralized bone by osteoclasts followed by the formation of bone matrix by the osteoblasts, which subsequently becomes mineralized. In some metabolic diseases, bone pathological features are associated with bone development problems but in others they are associated with bone remodeling. Here, we describe three examples of impaired bone development or remodeling in metabolic diseases, including work by others and the results from our research. In particular, we will focus on hereditary multiple exostosis (or osteochondromatosis), Gaucher disease, and the susceptibility to atypical femoral fracture in patients treated with bisphosphonates for several years.
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Affiliation(s)
- Jenny Serra-Vinardell
- Department of Genetics, Microbiology and Statistics, Faculty of Biology, Universitat de Barcelona, CIBERER, IBUB, IRSJD, Barcelona, Spain
- Section of Human Biochemical Genetics, Medical Genetics Branch, National Human Genome Research Institute, National Institutes of Health, Bethesda, Maryland
| | - Neus Roca-Ayats
- Department of Genetics, Microbiology and Statistics, Faculty of Biology, Universitat de Barcelona, CIBERER, IBUB, IRSJD, Barcelona, Spain
| | - Laura De-Ugarte
- Department of Anatomy and Cell Biology, Indiana University School of Medicine, Indianapolis, Indiana
- Department of Anatomy and Cell Biology, Indiana Center for Musculoskeletal Health, Indianapolis, Indiana
| | - Lluïsa Vilageliu
- Department of Genetics, Microbiology and Statistics, Faculty of Biology, Universitat de Barcelona, CIBERER, IBUB, IRSJD, Barcelona, Spain
| | - Susanna Balcells
- Department of Genetics, Microbiology and Statistics, Faculty of Biology, Universitat de Barcelona, CIBERER, IBUB, IRSJD, Barcelona, Spain
| | - Daniel Grinberg
- Department of Genetics, Microbiology and Statistics, Faculty of Biology, Universitat de Barcelona, CIBERER, IBUB, IRSJD, Barcelona, Spain
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D'Arienzo A, Andreani L, Sacchetti F, Colangeli S, Capanna R. Hereditary Multiple Exostoses: Current Insights. Orthop Res Rev 2019; 11:199-211. [PMID: 31853203 PMCID: PMC6916679 DOI: 10.2147/orr.s183979] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2019] [Accepted: 10/11/2019] [Indexed: 12/31/2022] Open
Abstract
Hereditary multiple exostoses (HME), also called hereditary multiple osteochondromas, is a rare genetic disorder characterized by multiple osteochondromas that grow near the growth plates of bones such as the ribs, pelvis, vertebrae and especially long bones. The disease presents with various clinical manifestations including chronic pain syndromes, restricted range of motion, limb deformity, short stature, scoliosis and neurovascular alteration. Malignant transformation of exostosis is rarely seen. The disease has no medical treatment and surgery is only recommended in symptomatic exostoses or in cases where a malignant transformation is suspected. HME is mainly caused by mutations and functional loss of the EXT1 and EXT2 genes which encode glycosyltransferases, an enzyme family involved in heparan sulfate (HS) synthesis. However, the peculiar molecular mechanism that leads to the structural changes of the cartilage and to osteochondroma formation is still being studied. Basic science studies have recently shown new insights about altering the molecular and cellular mechanism caused by HS deficiency. Pediatricians, geneticists and orthopedic surgeons play an important role in the study and treatment of this severe pathology. Despite the recent significant advances, we still need novel insights to better specify the role of HS in signal transduction. The purpose of this review was to analyze the most relevant aspects of HME from the literature review, give readers an important tool to understand its clinical features and metabolic-pathogenetic mechanism, and to identify an effective treatment method. We focused on the aspects of the disease related to clinical management and surgical treatment in order to give up-to-date information that could be useful for following best clinical practice.
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Affiliation(s)
- Antonio D'Arienzo
- Department of Translational Research on New Surgical and Medical Technologies, University of Pisa, Pisa, Italy
| | - Lorenzo Andreani
- Department of Translational Research on New Surgical and Medical Technologies, University of Pisa, Pisa, Italy
| | - Federico Sacchetti
- Department of Translational Research on New Surgical and Medical Technologies, University of Pisa, Pisa, Italy
| | - Simone Colangeli
- Department of Translational Research on New Surgical and Medical Technologies, University of Pisa, Pisa, Italy
| | - Rodolfo Capanna
- Department of Translational Research on New Surgical and Medical Technologies, University of Pisa, Pisa, Italy
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Gupta A, Ewing SA, Renaud DL, Hasadsri L, Raymond KM, Klee EW, Gavrilova RH. Developmental delay, coarse facial features, and epilepsy in a patient with EXT2 gene variants. Clin Case Rep 2019; 7:632-637. [PMID: 30997052 PMCID: PMC6452521 DOI: 10.1002/ccr3.2010] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2018] [Revised: 11/28/2018] [Accepted: 01/08/2019] [Indexed: 01/08/2023] Open
Abstract
We report a patient with developmental delay, autism, epilepsy, macrocephaly, facial dysmorphism, gastrointestinal, and behavioral issues due to EXT2 compound heterozygous likely pathogenic variants. This case report expands the EXT2 gene mutation database and the clinical spectrum of patients with deficiencies in the heparan sulfate pathway.
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Affiliation(s)
- Aditi Gupta
- Center for Individualized MedicineMayo ClinicRochesterMinnesota
- Department of Health Sciences ResearchMayo ClinicRochesterMinnesota
| | - Sarah A. Ewing
- Department of Clinical GenomicsMayo ClinicRochesterMinnesota
| | - Deborah L. Renaud
- Department of Pediatric and Adolescent MedicineMayo ClinicRochesterMinnesota
- Department of NeurologyMayo ClinicRochesterMinnesota
| | - Linda Hasadsri
- Department of Laboratory Medicine and PathologyMayo ClinicRochesterMinnesota
| | - Kimiyo M. Raymond
- Department of Clinical GenomicsMayo ClinicRochesterMinnesota
- Department of Laboratory Medicine and PathologyMayo ClinicRochesterMinnesota
| | - Eric W. Klee
- Center for Individualized MedicineMayo ClinicRochesterMinnesota
- Department of Health Sciences ResearchMayo ClinicRochesterMinnesota
- Department of Clinical GenomicsMayo ClinicRochesterMinnesota
- Department of Laboratory Medicine and PathologyMayo ClinicRochesterMinnesota
| | - Ralitza H. Gavrilova
- Department of Clinical GenomicsMayo ClinicRochesterMinnesota
- Department of NeurologyMayo ClinicRochesterMinnesota
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Yang A, Kim J, Jang JH, Lee C, Lee JE, Cho SY, Jin DK. Identification of a novel mutation in EXT2 in a fourth-generation Korean family with multiple osteochondromas and overview of mutation spectrum. Ann Hum Genet 2019; 83:160-170. [PMID: 30730578 DOI: 10.1111/ahg.12298] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2018] [Revised: 10/31/2018] [Accepted: 12/17/2018] [Indexed: 12/01/2022]
Abstract
Multiple osteochondromas (MOs) or hereditary multiple exostoses is a rare autosomal-dominant disease characterized by growths of MOs, which are benign cartilage-capped bone tumors that grow away from the growth plates. Almost 90% of MOs have a molecular explanation and 10% are unexplained. MOs are genetically heterogeneous with two causal genes on 8q24.11 (EXT1) and 11p12 (EXT2), with a higher frequency in EXT1. MO is a very rare genetic disorder, and the genotype-phenotype of MO with EXT2 mutation has not been well investigated in Korea. We present the clinical radiographic and molecular analysis of a four-generation Korean family with 11 MO-affected members (seven males and four females). The affected members from the third generation available for molecular analysis and their detailed medical histories showed moderate-to-severe phenotypes (clinical classes II-III), including bony deformities and limb misalignment with pain requiring surgical correction. The x-rays showed MOs in multiple sites. A novel EXT2 frameshift mutation (c.590delC, p.P197Qfs*73) was revealed by targeted exome sequencing in the affected members of this family. In this article, we not only expand the phenotypic-genotypic spectrum of MOs but also highlight the phenotypic heterogeneity in a family with the same mutation. In addition, we compiled the mutation spectrum of EXT2 from a literature review and identified that exon 2 of EXT2 is a mutation hot spot. Early medical attention with diagnosis of MO through careful examination of the clinical manifestations and genetic analysis can provide the opportunity to establish coordinated multispecialty management of the patient.
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Affiliation(s)
- Aram Yang
- Department of Pediatrics, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea
| | - Jinsup Kim
- Department of Pediatrics, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea
| | - Ja-Hyun Jang
- Green Cross Genome, Yongin-si, Republic of Korea
| | - Chung Lee
- Department of Health Sciences and Technology, SAIHST, Sungkyunkwan University, Seoul, Samsung Genome Institute, Samsung Medical Center, Seoul, Republic of Korea
| | - Ji-Eun Lee
- Department of Pediatrics, Inha University Hospital, Inha University Graduate School of Medicine, Incheon, Republic of Korea
| | - Sung Yoon Cho
- Department of Pediatrics, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea
| | - Dong-Kyu Jin
- Department of Pediatrics, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea
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Gentile M, Agolini E, Cocciadiferro D, Ficarella R, Ponzi E, Bellacchio E, Antonucci MF, Novelli A. Novel exostosin-2 missense variants in a family with autosomal recessive exostosin-2-related syndrome: further evidences on the phenotype. Clin Genet 2018; 95:165-171. [PMID: 30288735 DOI: 10.1111/cge.13458] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2018] [Revised: 09/26/2018] [Accepted: 09/29/2018] [Indexed: 12/23/2022]
Abstract
Biallelic exostosin-2 (EXT2) pathogenic variants have been described as the cause of the Seizures-Scoliosis-Macrocephaly syndrome (OMIM 616682) characterized by intellectual disability, facial dysmorphisms and seizures. More recently, it has been proposed to rename this disorder with the acronym AREXT2 (autosomal recessive EXT2-related syndrome). Here, we report the third family affected by AREXT2 syndrome, harboring compound missense variants in EXT2, p.Asp227Asn, and p.Tyr608Cys. In addition, our patients developed multiple exostoses, which were not observed in the previously described families. AREXT2 syndrome can be considered as a multiorgan Congenital Disorder of Glycosylation caused by a significant, but non-lethal, decrease in EXT2 expression, thereby affecting the synthesis of the heparan sulfate proteoglycans, which is relevant in many physiological processes. Our finding expands the clinical and molecular spectrum of the AREXT2 syndrome and suggests a possible genotype/phenotype correlation in the development of the exostoses.
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Affiliation(s)
- Mattia Gentile
- Department of Medical Genetics, Hospital Di Venere, Local Sanitary Agency of BARI, Bari, Italy
| | - Emanuele Agolini
- Laboratory of Medical Genetics, Ospedale Pediatrico Bambino Gesù, Rome, Italy
| | - Dario Cocciadiferro
- Laboratory of Medical Genetics, Ospedale Pediatrico Bambino Gesù, Rome, Italy
| | - Romina Ficarella
- Department of Medical Genetics, Hospital Di Venere, Local Sanitary Agency of BARI, Bari, Italy
| | - Emanuela Ponzi
- Department of Medical Genetics, Hospital Di Venere, Local Sanitary Agency of BARI, Bari, Italy
| | - Emanuele Bellacchio
- Laboratory of Medical Genetics, Ospedale Pediatrico Bambino Gesù, Rome, Italy
| | - Maria F Antonucci
- Department of Medical Genetics, Hospital Di Venere, Local Sanitary Agency of BARI, Bari, Italy
| | - Antonio Novelli
- Laboratory of Medical Genetics, Ospedale Pediatrico Bambino Gesù, Rome, Italy
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13
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Camacho J, Gutierrez LD, Rubio C, Suárez A, Amaya A. Multiple Hereditary Exostoses: Report of an EXT2 Gene Mutation in a Colombian Family. J Pediatr Genet 2018; 7:122-124. [PMID: 30105120 DOI: 10.1055/s-0038-1636998] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2017] [Accepted: 02/06/2018] [Indexed: 10/17/2022]
Abstract
Multiple hereditary exostoses (MHE) is a rare disease with autosomal dominant inheritance, caused by heterozygous germline mutations in the EXT1 or EXT2 genes. This disorder is characterized by the growth of prominences surrounded by cartilage in the growth plates and the long bones. Here, we report a family affected by MHE. In this family, a pathogenic variant c.544C > T (p. Arg182Ter) was identified in the EXT2 gene. This variant has been previously described in the literature, and here we are reporting the relationship with clinical findings. MHE is suspected according to the clinical manifestations; molecular research should be performed to establish the most frequent mutations. A support, diagnosis, and follow-up group should be created, and genetic counseling should be available for patients and families.
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Affiliation(s)
- Jhon Camacho
- Department of Pediatrics, Fundación Universitaria de Ciencias de la Salud, Hospital de San José, Bogotá D.C., Colombia
| | - Luz Dary Gutierrez
- Clinical Genetics, Fundación Universitaria de Ciencias de la Salud, Hospital de San José, Hospital Infantil Universitario de San José, Bogotá D.C., Colombia
| | - Cladelis Rubio
- Clinical Genetics, Fundación Universitaria de Ciencias de la Salud, Hospital de San José, Hospital Infantil Universitario de San José, Bogotá D.C., Colombia
| | - Alfonso Suárez
- Clinical Genetics, Fundación Universitaria de Ciencias de la Salud, Hospital de San José, Hospital Infantil Universitario de San José, Bogotá D.C., Colombia
| | - Angie Amaya
- Department of Pediatrics, Hospital de San José, Bogotá D.C., Colombia
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14
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El-Bazzal L, Atkinson A, Gillart AC, Obeid M, Delague V, Mégarbané A. A novel EXT2 mutation in a consanguineous family with severe developmental delay, microcephaly, seizures, feeding difficulties, and osteopenia extends the phenotypic spectrum of autosomal recessive EXT2-related syndrome (AREXT2). Eur J Med Genet 2019; 62:259-64. [PMID: 30075207 DOI: 10.1016/j.ejmg.2018.07.025] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2018] [Revised: 07/12/2018] [Accepted: 07/28/2018] [Indexed: 12/31/2022]
Abstract
We report a consanguineous family where 2 boys presented with developmental delay, hypotonia, microcephaly, seizures, gastro-intestinal abnormalities, osteopenia, and neurological regression. Whole exome sequencing performed in one of the boys revealed the presence of a novel homozygous missense variant in the EXT2 gene: c.11C > T (p.Ser4Leu). Segregation analysis by Sanger sequencing confirmed homozygous by descent autosomal recessive transmission of this mutation. Another family was previously reported with homozygous mutations in this gene in four siblings affected with a nearly similar clinical condition (Farhan et al., 2015). We discuss the similarities and differences between the two syndromes and propose AREXT2 as a new acronym for EXT2-related diseases.
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15
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Abstract
Introduction Hereditary multiple exostoses (HME) is a rare congenital pediatric disorder characterized by osteochondromas forming next to the growth plates in young patients. The osteochondromas cause multiple health problems that include skeletal deformities and chronic pain. Surgery is used to remove the most symptomatic osteochondromas but because of their large number, many are left in place, causing life-long problems and increasing the probability of malignant transformation. There is no other treatment to prevent or reduce osteochondromas formation at present. Areas covered Recent studies reviewable through PubMed are providing new insights into cellular and molecular mechanisms of osteochondroma development. The resulting data are suggesting rational and plausible new therapeutic strategies for osteochondroma prevention some of which are being tested in HME animal models and one of which is part of a just announced clinical trial. Expert Commentary This section summarizes and evaluates such strategies and points also to possible future alternatives.
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Affiliation(s)
- Maurizio Pacifici
- Translational Research Program in Pediatric Orthopaedics, Division of Orthopaedic Surgery, The Children's Hospital of Philadelphia, Philadelphia, PA 19104
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16
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Santos SCL, Rizzo IMPO, Takata RI, Speck‐Martins CE, Brum JM, Sollaci C. Analysis of mutations in EXT1 and EXT2 in Brazilian patients with multiple osteochondromas. Mol Genet Genomic Med 2018. [PMID: 29529714 PMCID: PMC6014457 DOI: 10.1002/mgg3.382] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Background Multiple osteochondromas is a dysplasia characterized by growth of two or more osteochondromas. It is genetically heterogeneous, caused by pathogenic variants in EXT1 or EXT2 genes in 70%–90% of patients. The EXT1 is more often mutated than EXT2 gene, with a variable prevalence between populations. There are no data about EXT1 and EXT2 pathogenic variants in patients with multiple osteochondromas in Brazilian population. The aim of this survey is to characterize these to determine the genotype profile of this population. Methods DNA sequencing (Sanger Method) and MLPA analysis were performed to identify point mutations and deletions/duplications in the sample of 153 patients in 114 families. Results Germline variants were identified in 83% of families in which EXT2 variants were detected in 46% and EXT1 in 37% of cases. No variants were detected in 17% of them. We identified 50 different variants, 33 (13 frameshift, 11 nonsense, 5 missense, 2 splice site mutation, and 2 large deletions) in EXT1 and 17 (6 frameshift, 6 splice site mutation, 3 nonsense, 1 missense, and 1 large deletion) in EXT2. Of all 50 variants, 31 (62%) were novel, including 20 out of 33 (60,6%) EXT1 and 11 out of 17 (64.7%) EXT2 alleles. The vast majority of variants (88%) were “loss‐of‐function” and two novel hotspots in EXT2 gene were observed in our study. Conclusion The prevalence of variants detected in the EXT2 gene differs from other researches from Latin America, European, and Asian population. This uncommon prevalence could be related with the newly characterized variant hotspot sites detected in EXT2 gene (p.Ala409Profs*26 and p.Ser290*). A high number of novel variants were also identified indicating that Brazilian population has a unique genetic profile. Characterizing this population and establishing its genotype is essential to understand the molecular pathogenesis of this disease in Brazil.
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Affiliation(s)
- Savana C. L. Santos
- Molecular Pathology LaboratorySARAH Network of Rehabilitation HospitalsBrasíliaBrazil
| | | | - Reinaldo I. Takata
- Molecular Pathology LaboratorySARAH Network of Rehabilitation HospitalsBrasíliaBrazil
| | | | - Jaime M. Brum
- Department of Clinical GeneticsSARAH Network of Rehabilitation HospitalsBrasíliaBrazil
| | - Claudio Sollaci
- Department of OrthopaedicsSARAH Network of Rehabilitation HospitalsBrasíliaBrazil
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Abstract
Multiple hereditary exostoses (MHE) is an autosomal dominant disorder that affects about 1 in 50,000 children worldwide. MHE, also known as hereditary multiple exostoses (HME) or multiple osteochondromas (MO), is characterized by cartilage-capped outgrowths called osteochondromas that develop adjacent to the growth plates of skeletal elements in young patients. These benign tumors can affect growth plate function, leading to skeletal growth retardation, or deformations, and can encroach on nerves, tendons, muscles, and other surrounding tissues and cause motion impairment, chronic pain, and early onset osteoarthritis. In about 2-5% of patients, the osteochondromas can become malignant and life threatening. Current treatments consist of surgical removal of the most symptomatic tumors and correction of the major skeletal defects, but physical difficulties and chronic pain usually continue and patients may undergo multiple surgeries throughout life. Thus, there is an urgent need to find new treatments to prevent or reverse osteochondroma formation. The 2016 International MHE Research Conference was convened to provide a forum for the presentation of the most up-to-date and advanced clinical and basic science data and insights in MHE and related fields; to stimulate the forging of new perspectives, collaborations, and venues of research; and to publicize key scientific findings within the biomedical research community and share insights and relevant information with MHE patients and their families. This report provides a description, review, and assessment of all the exciting and promising studies presented at the Conference and delineates a general roadmap for future MHE research targets and goals.
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Affiliation(s)
- Anne Q. Phan
- Department of Cellular and Molecular Medicine, Glycobiology Research and Training Center, University of California, San Diego, La Jolla, CA, USA
| | - Maurizio Pacifici
- Translational Research Program in Pediatric Orthopaedics, Division of Orthopaedic Surgery, The Children’s Hospital of Philadelphia, Philadelphia, PA, USA
| | - Jeffrey D. Esko
- Department of Cellular and Molecular Medicine, Glycobiology Research and Training Center, University of California, San Diego, La Jolla, CA, USA
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18
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Pacifici M. The pathogenic roles of heparan sulfate deficiency in hereditary multiple exostoses. Matrix Biol 2017; 71-72:28-39. [PMID: 29277722 DOI: 10.1016/j.matbio.2017.12.011] [Citation(s) in RCA: 46] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2017] [Revised: 12/19/2017] [Accepted: 12/19/2017] [Indexed: 12/20/2022]
Abstract
Heparan sulfate (HS) is an essential component of cell surface and matrix proteoglycans (HS-PGs) that include syndecans and perlecan. Because of their unique structural features, the HS chains are able to specifically interact with signaling proteins -including bone morphogenetic proteins (BMPs)- via their HS-binding domain, regulating protein availability, distribution and action on target cells. Hereditary Multiple Exostoses (HME) is a rare pediatric disorder linked to germline heterozygous loss-of-function mutations in EXT1 or EXT2 that encode Golgi-resident glycosyltransferases responsible for HS synthesis, resulting in a systemic HS deficiency. HME is characterized by cartilaginous/bony tumors -called osteochondromas or exostoses- that form within perichondrium in long bones, ribs and other elements. This review examines most recent studies in HME, framing them in the context of classic studies. New findings show that the spectrum of EXT mutations is larger than previously realized and the clinical complications of HME extend beyond the skeleton. Osteochondroma development requires a somatic "second hit" that would complement the germline EXT mutation to further decrease HS production and/levels at perichondrial sites of osteochondroma induction. Cellular studies have shown that the steep decreases in local HS levels: derange the normal homeostatic signaling pathways keeping perichondrium mesenchymal; cause excessive BMP signaling; and provoke ectopic chondrogenesis and osteochondroma formation. Data from HME mouse models have revealed that systemic treatment with a BMP signaling antagonist markedly reduces osteochondroma formation. In sum, recent studies have provided major new insights into the molecular and cellular pathogenesis of HME and the roles played by HS deficiency. These new insights have led to the first ever proof-of-principle demonstration that osteochondroma formation is a druggable process, paving the way toward the creation of a clinically-relevant treatment.
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Affiliation(s)
- Maurizio Pacifici
- Translational Research Program in Pediatric Orthopaedics, Division of Orthopaedic Surgery, The Children's Hospital of Philadelphia, Philadelphia, PA 19104, United States.
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19
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Medek K, Zeman J, Honzík T, Hansíková H, Švecová Š, Beránková K, Kučerová Vidrová V, Kuklík M, Chomiak J, Tesařová M. Hereditary Multiple Exostoses: Clinical, Molecular and Radiologic Survey in 9 Families. Prague Med Rep 2017; 118:87-94. [PMID: 28922105 DOI: 10.14712/23362936.2017.8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022] Open
Abstract
Hereditary multiple exostoses (HME) represents a heterogeneous group of diseases often associated with progressive skeletal deformities. Most frequently, mutations in EXT1 and EXT2 genes with autosomal dominant inheritance are responsible for HME. In our group of 9 families with HME we evaluated the clinical course of the disease and analysed molecular background using Sanger sequencing and MLPA in EXT1 and EXT2 genes. The mean age in our group of patients, when the first exostosis was recognised was 4.5 years (range 2-10 years) and the number of exostoses per one patient documented on X-ray ranged from 2 to 54. Most of the exostoses developed before the growth was completed and they were dominantly localised in the distal femurs, proximal tibia, proximal humerus and distal radius. In all patients, at least one to 8 surgeries were necessary due to complaints and local complications, but neither patient developed malignant transformation. In half of the patients, the disease resulted in short stature. DNA analyses were positive in 7 families. In five probands, different EXT1 gene mutations resulting in premature stop-codon (p.Gly124Argfs*65, p.Leu191*, p.Trp364Lysfs*11, p.Val371Glyfs*10, p.Leu490Profs*31) were found. In two probands, nonsense mutations were found in EXT2 gene (p.Val187Profs*115, p.Cys319fs*46). Five mutations have been novel and two mutations have occurred de novo in probands. Although the risk for malignant transformation is usually low, especially in patients with low number of exostoses, early diagnostics and longitudinal follow up of patients is of a big importance, because early surgery can prevent progression of secondary bone deformities.
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Affiliation(s)
- Karel Medek
- Department of Pediatrics and Adolescent Medicine, First Faculty of Medicine, Charles University and General University Hospital in Prague, Prague, Czech Republic
| | - Jiří Zeman
- Department of Pediatrics and Adolescent Medicine, First Faculty of Medicine, Charles University and General University Hospital in Prague, Prague, Czech Republic
| | - Tomáš Honzík
- Department of Pediatrics and Adolescent Medicine, First Faculty of Medicine, Charles University and General University Hospital in Prague, Prague, Czech Republic
| | - Hana Hansíková
- Department of Pediatrics and Adolescent Medicine, First Faculty of Medicine, Charles University and General University Hospital in Prague, Prague, Czech Republic
| | - Štěpánka Švecová
- Department of Pediatrics and Adolescent Medicine, First Faculty of Medicine, Charles University and General University Hospital in Prague, Prague, Czech Republic
| | - Kamila Beránková
- Department of Pediatrics and Adolescent Medicine, First Faculty of Medicine, Charles University and General University Hospital in Prague, Prague, Czech Republic
| | - Vendula Kučerová Vidrová
- Department of Pediatrics and Adolescent Medicine, First Faculty of Medicine, Charles University and General University Hospital in Prague, Prague, Czech Republic
| | | | - Jiří Chomiak
- Department of Orthopaedics, First Faculty of Medicine, Charles University and Na Bulovce Hospital, Prague, Czech Republic
| | - Markéta Tesařová
- Department of Pediatrics and Adolescent Medicine, First Faculty of Medicine, Charles University and General University Hospital in Prague, Prague, Czech Republic.
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Abstract
PURPOSE OF REVIEW Hereditary multiple exostoses (HME) is a complex musculoskeletal pediatric disorder characterized by osteochondromas that form next to the growth plates of many skeletal elements, including long bones, ribs, and vertebrae. Due to its intricacies and unresolved issues, HME continues to pose major challenges to both clinicians and biomedical researchers. The purpose of this review is to describe and analyze recent advances in this field and point to possible targets and strategies for future biologically based therapeutic intervention. RECENT FINDINGS Most HME cases are linked to loss-of-function mutations in EXT1 or EXT2 that encode glycosyltransferases responsible for heparan sulfate (HS) synthesis, leading to HS deficiency. Recent genomic inquiries have extended those findings but have yet to provide a definitive genotype-phenotype correlation. Clinical studies emphasize that in addition to the well-known skeletal problems caused by osteochondromas, HME patients can experience, and suffer from, other symptoms and health complications such as chronic pain and nerve impingement. Laboratory work has produced novel insights into alterations in cellular and molecular mechanisms instigated by HS deficiency and subtending onset and growth of osteochondroma and how such changes could be targeted toward therapeutic ends. HME is a rare and orphan disease and, as such, is being studied only by a handful of clinical and basic investigators. Despite this limitation, significant advances have been made in the last few years, and the future bodes well for deciphering more thoroughly its pathogenesis and, in turn, identifying the most effective treatment for osteochondroma prevention.
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Affiliation(s)
- Maurizio Pacifici
- Translational Research Program in Pediatric Orthopaedics, Abramson Research Center, 902D, Division of Orthopaedic Surgery, Department of Surgery, The Children's Hospital of Philadelphia, Philadelphia, PA, 19104, USA.
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21
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Beltrami G, Ristori G, Scoccianti G, Tamburini A, Capanna R. Hereditary Multiple Exostoses: a review of clinical appearance and metabolic pattern. ACTA ACUST UNITED AC 2016; 13:110-118. [PMID: 27920806 DOI: 10.11138/ccmbm/2016.13.2.110] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Hereditary multiple exostoses (HME) is an inherited genetic condition characterized by the presence of multiple exostoses (osteochondromas). MHE is a relatively rare autosomal dominant disorder, mainly caused by loss of function mutations in two genes: exostosin-1 (EXT1) and exostosin-2 (EXT2). These genes are linked to heparan sulfate (HS) synthesis, but the specific molecular mechanism leading to the disruption of the cartilage structure and the consequent exostoses formation is still not resolved. The aim of this paper is to encounter the main aspects of HME reviewing the literature, in order to improve clinical features and evolution, and the metabolic-pathogenetic mechanisms underlying. Although MHE may be asymptomatic, a wide spectrum of clinical manifestations is found in paediatric patients with this disorder. Pain is experienced by the majority of patients, even restricted motion of the joint is often encountered. Sometimes exostoses can interfere with normal development of the growth plate, giving rise to limb deformities, low stature and scoliosis. Other many neurovascular and associated disorders can lead to surgery. The most feared complication is the malignant transformation of an existing osteochondroma into a secondary peripheral chondrosarcoma, during adulthood. The therapeutic approach to HME is substantially surgical, whereas the medical one is still at an experimental level. In conclusion, HME is a complex disease where the paediatrician, the geneticist and the orthopaedic surgeon play an interchangeable role in diagnosis, research and therapy. We are waiting for new studies able to explain better the role of HS in signal transduction, because it plays a role in other bone and cartilage diseases (in particular malignant degeneration) as well as in skeletal embryology.
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Affiliation(s)
- Giovanni Beltrami
- Department of Orthopaedic Oncology and Reconstructive Surgery, "Azienda Ospedaliera Universitaria Careggi", Firenze, Italy
| | - Gabriele Ristori
- Department of Orthopaedic Oncology and Reconstructive Surgery, "Azienda Ospedaliera Universitaria Careggi", Firenze, Italy
| | - Guido Scoccianti
- Department of Orthopaedic Oncology and Reconstructive Surgery, "Azienda Ospedaliera Universitaria Careggi", Firenze, Italy
| | - Angela Tamburini
- Hematology-Oncology Service, Department of Pediatrics, "Azienda Ospedaliera Universitaria Meyer", Firenze, Italy
| | - Rodolfo Capanna
- Department of Orthopaedic Oncology and Reconstructive Surgery, "Azienda Ospedaliera Universitaria Careggi", Firenze, Italy
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22
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Xia P, Xu H, Shi Q, Li D. Identification of a novel frameshift mutation of the EXT2 gene in a family with multiple osteochondroma. Oncol Lett 2015; 11:105-110. [PMID: 26870176 PMCID: PMC4727190 DOI: 10.3892/ol.2015.3844] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2014] [Accepted: 10/02/2015] [Indexed: 01/31/2023] Open
Abstract
Multiple osteochondroma (MO), also known as multiple hereditary exostoses, is an autosomal dominant skeletal disorder with characteristic multiple cartilage-capped tumours (osteochondromas or exostoses) growing outward from the metaphyseal region of the long tubular bones. Mutations in exostosin glycosyltransferase 1 (EXT1) or EXT2 are the most commonly associated mutations with MO and are responsible for 70–95% of cases. In the present study, a genetic analysis was performed on a large family with MO using polymerase chain reaction and direct DNA sequencing of the entire coding regions of EXT1 and EXT2. Sanger sequencing identified a novel heterozygous frameshift mutation, c.119_120delCT (p.Thr40ArgfsX15), in exon 2 of the EXT2 gene in the proband and all other affected individuals, while this deleterious mutation was not detected in the healthy family members and normal controls. The c.119_120delCT mutation is located in the transmembrane region of the EXT2 protein and results in a truncated EXT2 protein lacking 665 amino acids at the C-terminus, which includes the critical exostosin and glycosyltransferase family 64 domains. Thus, the present study identified a novel causative frameshift mutation in EXT2 from a large MO family. This study is useful for extending the known mutational spectrum of EXT2, for understanding the genetic basis of MO in the patients studied, and for further application of mutation screening in the genetic counseling and subsequent prenatal diagnosis of this family.
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Affiliation(s)
- Peng Xia
- Department of Spinal Surgery, Orthopedics Hospital, The Second Hospital of Jilin University, Changchun, Jilin 130041, P.R. China
| | - Haikun Xu
- Department of Cardiology, China-Japan Union Hospital of Jilin University, Changchun, Jilin 130033, P.R. China
| | - Qingyang Shi
- Center for Prenatal Diagnosis, The First Hospital of Jilin University, Changchun, Jilin 130021, P.R. China
| | - Dejun Li
- Center for Prenatal Diagnosis, The First Hospital of Jilin University, Changchun, Jilin 130021, P.R. China
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23
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Labonne JDJ, Vogt J, Reali L, Kong IK, Layman LC, Kim HG. A microdeletion encompassing PHF21A in an individual with global developmental delay and craniofacial anomalies. Am J Med Genet A 2015; 167A:3011-8. [PMID: 26333423 DOI: 10.1002/ajmg.a.37344] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2014] [Accepted: 08/12/2015] [Indexed: 11/09/2022]
Abstract
In Potocki-Shaffer syndrome (PSS), the full phenotypic spectrum is manifested when deletions are at least 2.1 Mb in size at 11p11.2. The PSS-associated genes EXT2 and ALX4, together with PHF21A, all map to this region flanked by markers D11S1393 and D11S1319. Being proximal to EXT2 and ALX4, a 1.1 Mb region containing 12 annotated genes had been identified by deletion mapping to explain PSS phenotypes except multiple exostoses and parietal foramina. Here, we report a male patient with partial PSS phenotypes including global developmental delay, craniofacial anomalies, minor limb anomalies, and micropenis. Using microarray, qPCR, RT-qPCR, and Western blot analyses, we refined the candidate gene region, which harbors five genes, by excluding two genes, SLC35C1 and CRY2, which resulted in a corroborating role of PHF21A in developmental delay and craniofacial anomalies. This microdeletion contains the least number of genes at 11p11.2 reported to date. Additionally, we also discuss the phenotypes observed in our patient with respect to those of published cases of microdeletions across the Potocki-Shaffer interval.
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Affiliation(s)
- Jonathan D J Labonne
- Section of Reproductive Endocrinology, Infertility and Genetics, Department of Obstetrics and Gynecology, Georgia Regents University, Augusta, Georgia.,Department of Neuroscience and Regenerative Medicine, Georgia Regents University, Augusta, Georgia
| | - Julie Vogt
- West Midlands Regional Genetics Service, Birmingham Women's Hospital, Birmingham, United Kingdom
| | - Lisa Reali
- West Midlands Regional Genetics Service, Birmingham Women's Hospital, Birmingham, United Kingdom
| | - Il-Keun Kong
- Department of Animal Science, Division of Applied Life Science, Gyeongsang National University, Jinju, Gyeongsangnam-do, Republic of Korea
| | - Lawrence C Layman
- Section of Reproductive Endocrinology, Infertility and Genetics, Department of Obstetrics and Gynecology, Georgia Regents University, Augusta, Georgia.,Department of Neuroscience and Regenerative Medicine, Georgia Regents University, Augusta, Georgia.,Department of Physiology, Medical College of Georgia, Georgia Regents University, Augusta, Georgia
| | - Hyung-Goo Kim
- Section of Reproductive Endocrinology, Infertility and Genetics, Department of Obstetrics and Gynecology, Georgia Regents University, Augusta, Georgia.,Department of Neuroscience and Regenerative Medicine, Georgia Regents University, Augusta, Georgia
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24
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Farhan SMK, Wang J, Robinson JF, Prasad AN, Rupar CA, Siu VM, Hegele RA. Old gene, new phenotype: mutations in heparan sulfate synthesis enzyme, EXT2 leads to seizure and developmental disorder, no exostoses. J Med Genet 2015; 52:666-75. [PMID: 26246518 DOI: 10.1136/jmedgenet-2015-103279] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2015] [Accepted: 07/06/2015] [Indexed: 01/24/2023]
Abstract
BACKGROUND Heparan sulfate proteoglycans are vital components of the extracellular matrix and are essential for cellular homeostasis. Many genes are involved in modulating heparan sulfate synthesis, and when these genes are mutated, they can give rise to early-onset developmental disorders affecting multiple body systems. Herein, we describe a consanguineous family of four sibs with a novel disorder, which we designate as seizures-scoliosis-macrocephaly syndrome, characterised by seizures, intellectual disability, hypotonia, scoliosis, macrocephaly, hypertelorism and renal dysfunction. METHODS Our application of autozygosity mapping and whole-exome sequencing allowed us to identify mutations in the patients. To confirm the autosomal-recessive mode of inheritance, all available family members were genotyped. We also studied the effect of these mutations on protein expression and function in patient cells and using an in vitro system. RESULTS We identified two homozygous mutations p.Met87Arg and p.Arg95 Cys in exostosin 2, EXT2, a ubiquitously expressed gene that encodes a glycosyltransferase required for heparan sulfate synthesis. In patient cells, we observed diminished EXT2 expression and function. We also performed an in vitro assay to determine which mutation has a larger effect on protein expression and observed reduced EXT2 expression in constructs expressing either one of the mutations but a greater reduction when both residues were mutated. CONCLUSIONS In short, we have unravelled the genetic basis of a new recessive disorder, seizures-scoliosis-macrocephaly syndrome. Our results have implicated a well-characterised gene in a new developmental disorder and have further illustrated the spectrum of phenotypes that can arise due to errors in glycosylation.
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Affiliation(s)
- Sali M K Farhan
- Robarts Research Institute, London, Ontario, Canada Department of Biochemistry, Schulich School of Medicine and Dentistry, Western University, London, Ontario, Canada
| | - Jian Wang
- Robarts Research Institute, London, Ontario, Canada
| | | | - Asuri N Prasad
- Division of Clinical Neurological Sciences, Department of Pediatrics, London Health Sciences Centre, London, Ontario, Canada Children's Health Research Institute, London, Ontario, Canada
| | - C Anthony Rupar
- Department of Biochemistry, Schulich School of Medicine and Dentistry, Western University, London, Ontario, Canada Children's Health Research Institute, London, Ontario, Canada Medical Genetics Program, Department of Pediatrics, London Health Sciences Centre, London, Ontario, Canada
| | - Victoria M Siu
- Department of Biochemistry, Schulich School of Medicine and Dentistry, Western University, London, Ontario, Canada Children's Health Research Institute, London, Ontario, Canada Medical Genetics Program, Department of Pediatrics, London Health Sciences Centre, London, Ontario, Canada
| | | | - Robert A Hegele
- Robarts Research Institute, London, Ontario, Canada Department of Biochemistry, Schulich School of Medicine and Dentistry, Western University, London, Ontario, Canada
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Abstract
PURPOSE/AIM OF THE STUDY Exostosin 2 (EXT2) is involved in early pancreatic development and the regulation of insulin synthesis. In this study, we aim to evaluate the contribution of EXT2 to the genetic pathogenesis of type 2 diabetes and its related traits in the Chinese population. MATERIALS AND METHODS A case-control study in a Chinese Han population was conducted that included 4766 patients with type 2 diabetes and 4596 control subjects from 14 different regions of China. Three single nucleotide polymorphism (SNP), rs3740878, rs11037909 and rs1113132, in the EXT2 gene were genotyped using the Illumina GoldenGate Genotyping assay. RESULTS After adjusting for sex, age and body mass index, logistic regression analysis revealed that the EXT2 gene had no association with type 2 diabetes using an additive genetic model [rs3740878 (Odds Ratio (OR) = 0.996, 95% confidence interval (CI) 0.928-1.069, p = 0.910), rs11037909 (OR = 1.003, 95%CI 0.933-1.078, p = 0.931), and rs1113132 (OR = 0.993, 95% CI 0.925-1.065, p = 0.842)]. None of these SNPs were associated with beta cell function as determined using the baseline disposition index, early phase insulin secretion and Oral Glucose Tolerance Test (OGTT) total disposition index. CONCLUSIONS Our study suggests that the EXT2 gene might not have a major role in the development of type 2 diabetes in the Chinese population.
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Affiliation(s)
- Qian Ren
- Department of Endocrinology and Metabolism, Peking University People's Hospital, Peking University Diabetes Center , Beijing , P.R. China and
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Abstract
BACKGROUND Multiple hereditary exostoses (MHE) is characterized by multiple benign projections of bone capped by cartilage, most numerous in metaphyses of long bones. HME are usually inherited in autosomal dominant mode, chief genes EXT1 and EXT2. METHODS Two MHE patients were identified from clinic and enrolled in genetic study, complete coding regions of EXT1 and EXT2, including intron/exon boundaries, sequenced via DNA samples drawn from participants. RESULTS DNA sequencing revealed mutant EXT1 gene in both cases, within which frame-shift mutation c.447delC (p.Ser149fsX156) in exon1 and nonsense mutation c.2034T>G (p.Tyr678X) in exon10, emerged. Neither mutation was detected in control group. CONCLUSIONS Our results extended the spectrum of EXT1 mutations, revealing similar incidence of EXT1 and EXT2 in Taiwanese MHE patients.
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Affiliation(s)
- Wei-De Lin
- Department of Medical Research, China Medical University Hospital, Taichung, Taiwan ; School of Post Baccalaureate Chinese Medicine, China Medical University, Taichung, Taiwan
| | - Wuh-Liang Hwu
- Department of Pediatrics and Medical Genetics, National Taiwan University Hospital and National Taiwan University School of Medicine, Taipei, Taiwan
| | - Chung-Hsing Wang
- Department of Pediatrics, China Medical University Hospital, Taichung, Taiwan ; School of Medicine, China Medical University, Taichung, Taiwan
| | - Fuu-Jen Tsai
- Department of Medical Research, China Medical University Hospital, Taichung, Taiwan ; Department of Pediatrics, China Medical University Hospital, Taichung, Taiwan ; Department of Medical Genetics, China Medical University Hospital, Taichung, Taiwan ; School of Chinese Medicine, China Medical University, Taichung, Taiwan ; Department of Health and Nutrition Biotechnology, Asia University, Taichung, Taiwan ; Department of Pediatrics and Medical Genetics, China Medical University Hospital, No. 2, Yuh Der Road, 404 Taichung, Taiwan
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Busse-Wicher M, Wicher KB, Kusche-Gullberg M. The exostosin family: proteins with many functions. Matrix Biol 2014; 35:25-33. [PMID: 24128412 DOI: 10.1016/j.matbio.2013.10.001] [Citation(s) in RCA: 91] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2013] [Revised: 10/01/2013] [Accepted: 10/04/2013] [Indexed: 12/13/2022]
Abstract
Heparan sulfates are complex sulfated molecules found in abundance at cell surfaces and in the extracellular matrix. They bind to and influence the activity of a variety of molecules like growth factors, proteases and morphogens and are thus involved in various cell-cell and cell-matrix interactions. The mammalian EXT proteins have glycosyltransferase activities relevant for HS chain polymerization, however their exact role in this process is still confusing. In this review, we summarize current knowledge about the biochemical activities and some proposed functions of the members of the EXT protein family and their roles in human disease.
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Kang QL, Xu J, Zhang Z, He JW, Fu WZ, Zhang ZL. Mutation screening for the EXT1 and EXT2 genes in Chinese patients with multiple osteochondromas. Arch Med Res 2013; 44:542-8. [PMID: 24120389 DOI: 10.1016/j.arcmed.2013.09.008] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2013] [Accepted: 09/19/2013] [Indexed: 12/26/2022]
Abstract
BACKGROUND AND AIMS Multiple osteochondromas (MO), an autosomal dominant skeletal disease, is characterized by the presence of multiple cartilage-capped bone tumors (exostoses). Two genes with mutations that are most commonly associated with MO have been identified as EXT1 and EXT2, which are Exostosin-1 and Exostosin-2. In this study, a variety of EXT1 and EXT2 gene mutations were identified in ten Chinese families with MO. METHODS We investigated ten unrelated Chinese families involving a total of 46 patients who exhibited typical features of MO. The coding exons of EXT1 and EXT2 were sequenced after PCR amplification in ten probands. Radiological investigation was conducted simultaneously. RESULTS Nine mutations were identified, five in EXT1 and four in EXT2, of which three were de novo mutations and six were novel mutations. One proband carried mutations in both EXT1 and EXT2 simultaneously, and three probands, including one sporadic case and two familial cases, had no detectable mutations. CONCLUSIONS Our findings are useful for extending the mutational spectrum in EXT1 and EXT2 and understanding the genetic basis of MO in Chinese patients.
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Affiliation(s)
- Qing-lin Kang
- Department of Orthopedic Surgery, Shanghai Jiao Tong University Affiliated Sixth People's Hospital, Shanghai, PR China
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Wu Y, Xing X, Xu S, Ma H, Cao L, Wang S, Luo Y. Novel and recurrent mutations in the EXT1 and EXT2 genes in Chinese kindreds with multiple osteochondromas. J Orthop Res 2013; 31:1492-9. [PMID: 23629877 DOI: 10.1002/jor.22378] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/10/2012] [Accepted: 04/04/2013] [Indexed: 02/04/2023]
Abstract
Multiple osteochondromas (MO) is an autosomal dominant hereditary disorder caused by heterozygous germline mutations in the exostonsin-1 (EXT1) or exostosin-2 (EXT2) genes. In this study, we screened mutations in the EXT1/EXT2 genes in four Chinese MO kindreds by direct sequencing. Three point mutations were detected, including a nonsense mutation in the EXT2 gene (c.544C > T) and two splice site mutations in the EXT1 and EXT2 genes, respectively (EXT1: c.1883 + 1G > A and EXT2: c.1173 + 1G > T). Although splice site mutations constitute at least 10% of all mutations that cause MO, there has been limited research on their pathogenic effect on RNA processing due to poor availability of patient RNA samples. In this study, ex vivo and in vivo splicing assays were used to investigate the effect of EXT1 and EXT2 mutations on aberrant splicing at the mRNA level. Our results indicate that identified splice site mutations can cause either cryptic splice site usage or exon skipping.
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Affiliation(s)
- Yuhong Wu
- The Research Center for Medical Genomics, Key Laboratory of Medical Cell Biology, Ministry of Education, China Medical University, Shenyang, 110001, China
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