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Fox SC, Waskiewicz AJ. Transforming growth factor beta signaling and craniofacial development: modeling human diseases in zebrafish. Front Cell Dev Biol 2024; 12:1338070. [PMID: 38385025 PMCID: PMC10879340 DOI: 10.3389/fcell.2024.1338070] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2023] [Accepted: 01/18/2024] [Indexed: 02/23/2024] Open
Abstract
Humans and other jawed vertebrates rely heavily on their craniofacial skeleton for eating, breathing, and communicating. As such, it is vital that the elements of the craniofacial skeleton develop properly during embryogenesis to ensure a high quality of life and evolutionary fitness. Indeed, craniofacial abnormalities, including cleft palate and craniosynostosis, represent some of the most common congenital abnormalities in newborns. Like many other organ systems, the development of the craniofacial skeleton is complex, relying on specification and migration of the neural crest, patterning of the pharyngeal arches, and morphogenesis of each skeletal element into its final form. These processes must be carefully coordinated and integrated. One way this is achieved is through the spatial and temporal deployment of cell signaling pathways. Recent studies conducted using the zebrafish model underscore the importance of the Transforming Growth Factor Beta (TGF-β) and Bone Morphogenetic Protein (BMP) pathways in craniofacial development. Although both pathways contain similar components, each pathway results in unique outcomes on a cellular level. In this review, we will cover studies conducted using zebrafish that show the necessity of these pathways in each stage of craniofacial development, starting with the induction of the neural crest, and ending with the morphogenesis of craniofacial elements. We will also cover human skeletal and craniofacial diseases and malformations caused by mutations in the components of these pathways (e.g., cleft palate, craniosynostosis, etc.) and the potential utility of zebrafish in studying the etiology of these diseases. We will also briefly cover the utility of the zebrafish model in joint development and biology and discuss the role of TGF-β/BMP signaling in these processes and the diseases that result from aberrancies in these pathways, including osteoarthritis and multiple synostoses syndrome. Overall, this review will demonstrate the critical roles of TGF-β/BMP signaling in craniofacial development and show the utility of the zebrafish model in development and disease.
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2
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FGF9-Associated Multiple Synostoses Syndrome Type 3 in a Multigenerational Family. Genes (Basel) 2023; 14:genes14030724. [PMID: 36980996 PMCID: PMC10048304 DOI: 10.3390/genes14030724] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2023] [Revised: 03/08/2023] [Accepted: 03/13/2023] [Indexed: 03/18/2023] Open
Abstract
Multiple synostoses syndrome (OMIM: #186500, #610017, #612961, #617898) is a genetically heterogeneous group of autosomal dominant diseases characterized by abnormal bone unions. The joint fusions frequently involve the hands, feet, elbows or vertebrae. Pathogenic variants in FGF9 have been associated with multiple synostoses syndrome type 3 (SYNS3). So far, only five different missense variants in FGF9 that cause SYNS3 have been reported in 18 affected individuals. Unlike other multiple synostoses syndromes, conductive hearing loss has not been reported in SYNS3. In this report, we describe the clinical and selected radiological findings in a large multigenerational family with a novel missense variant in FGF9: c.430T>C, p.(Trp144Arg). We extend the phenotypic spectrum of SYNS3 by suggesting that cleft palate and conductive hearing loss are part of the syndrome and highlight the high degree of intrafamilial phenotypic variability. These findings should be considered when counseling affected individuals.
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3
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Yu T, Li G, Wang C, Li N, Yao R, Wang J. Defective Joint Development and Maintenance in GDF6-Related Multiple Synostoses Syndrome. J Bone Miner Res 2023; 38:568-577. [PMID: 36744814 DOI: 10.1002/jbmr.4785] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/11/2022] [Revised: 01/31/2023] [Accepted: 02/01/2023] [Indexed: 02/07/2023]
Abstract
Multiple synostoses syndromes (SYNS) are a group of rare genetic bone disorders characterized by multiple joint fusions. We previously reported an SYNS4-causing GDF6 c.1330 T > A (p.Tyr444Asn) mutation, which reduced Noggin-induced GDF6 inhibition and enhanced SMAD1/5/8 signaling. However, the mechanisms by which GDF6 gain-of-function mutation alters joint formation and the comprehensive molecular portraits of SYNS4 remain unclear. Herein, we introduce the p.Tyr443Asn (orthologous to the human GDF6 p.Tyr444Asn) mutation into the mouse Gdf6 locus and report the results of extensive phenotype analysis, joint development investigation, and transcriptome profiling of Gdf6 p.Tyr443Asn limb buds. Gdf6 p.Tyr443Asn knock-in mice recapitulated the morphological features of human SYNS4, showing joint fusion in the wrists, ankles, phalanges, and auditory ossicles. Analysis of mouse embryonic forelimbs demonstrated joint interzone formation defects and excess chondrogenesis in Gdf6 p.Tyr443Asn knock-in mice. Further, RNA sequencing of forelimb buds revealed enhanced bone formation and upregulated bone morphogenetic protein (BMP) signaling in mice carrying the Gdf6 p.Tyr443Asn mutation. Because tightly regulated BMP signaling is critical for skeletal development and joint morphogenesis, our study shows that enhancing GDF6 activity has a significant impact on both prenatal joint development and postnatal joint maintenance. © 2023 American Society for Bone and Mineral Research (ASBMR).
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Affiliation(s)
- Tingting Yu
- Department of Medical Genetics and Molecular Diagnostic Laboratory, Shanghai Children's Medical Center, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
| | - Guoqiang Li
- Department of Medical Genetics and Molecular Diagnostic Laboratory, Shanghai Children's Medical Center, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
| | - Chen Wang
- Department of Laboratory Medicine, Zhongshan Hospital, Fudan University, Shanghai, China
| | - Niu Li
- Department of Medical Genetics and Molecular Diagnostic Laboratory, Shanghai Children's Medical Center, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
| | - Ruen Yao
- Department of Medical Genetics and Molecular Diagnostic Laboratory, Shanghai Children's Medical Center, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
| | - Jian Wang
- Department of Medical Genetics and Molecular Diagnostic Laboratory, Shanghai Children's Medical Center, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
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4
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Dobson SM, Kiss C, Borschneck D, Heath KE, Gross A, Glucksman MJ, Guerin A. Novel
FGF9
variant contributes to multiple synostoses syndrome 3. Am J Med Genet A 2022; 188:2162-2167. [DOI: 10.1002/ajmg.a.62729] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2021] [Revised: 02/26/2022] [Accepted: 03/04/2022] [Indexed: 11/07/2022]
Affiliation(s)
| | - Courtney Kiss
- Division of Medical Genetics, Department of Pediatrics Queen’s University Kingston Ontario Canada
| | | | - Karen E. Heath
- Institute of Medical & Molecular Genetics (INGEMM), Hospital Universitario La Paz, IdiPAZ Universidad de Madrid Madrid Spain
- Skeletal dysplasia multidisciplinary Unit and ERN‐BOND Hospital Universitario La Paz Madrid Spain
- CIBERER, ISCIII Madrid Spain
| | - Adrian Gross
- Center for Proteomics and Molecular Therapeutics, Department of Biochemistry and Molecular Biology, Chicago Medical School Rosalind Franklin University of Medicine and Science North Chicago Illinois USA
| | | | - Andrea Guerin
- Division of Medical Genetics, Department of Pediatrics Queen’s University Kingston Ontario Canada
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5
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GDF6 Knockdown in a Family with Multiple Synostosis Syndrome and Speech Impairment. Genes (Basel) 2021; 12:genes12091354. [PMID: 34573339 PMCID: PMC8470939 DOI: 10.3390/genes12091354] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2021] [Revised: 08/24/2021] [Accepted: 08/26/2021] [Indexed: 11/16/2022] Open
Abstract
Multiple synostoses syndrome type 4 (SYNS4; MIM 617898) is an autosomal dominant disorder characterized by carpal-tarsal coalition and otosclerosis-associated hearing loss. SYSN4 has been associated with GDF6 gain-of-function mutations. Here we report a five-generation SYNS4 family with a reduction in GDF6 expression resulting from a chromosomal breakpoint 3' of GDF6. A 30-year medical history of the family indicated bilateral carpal-tarsal coalition in ~50% of affected family members and acquired otosclerosis-associated hearing loss in females only, whereas vertebral fusion was present in all affected family members, most of whom were speech impaired. All vertebral fusions were acquired postnatally in progressive fashion from a very early age. Thinning across the 2nd cervical vertebral interspace (C2-3) in the proband during infancy progressed to block fusion across C2-7 and T3-7 later in life. Carpal-tarsal coalition and pisiform expansion were bilaterally symmetrical within, but varied greatly between, affected family members. This is the first report of SYNS4 in a family with reduced GDF6 expression indicating a prenatal role for GDF6 in regulating development of the joints of the carpals and tarsals, the pisiform, ears, larynx, mouth and face and an overlapping postnatal role in suppression of aberrant ossification and synostosis of the joints of the inner ear (otosclerosis), larynx and vertebrae. RNAseq gene expression analysis indicated >10 fold knockdown of NOMO3, RBMXL1 and NEIL2 in both primary fibroblast cultures and fresh white blood cells. Together these results provide greater insight into the role of GDF6 in skeletal joint development.
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Bademci G, Abad C, Cengiz FB, Seyhan S, Incesulu A, Guo S, Fitoz S, Atli EI, Gosstola NC, Demir S, Colbert BM, Seyhan GC, Sineni CJ, Duman D, Gurkan H, Morton CC, Dykxhoorn DM, Walz K, Tekin M. Long-range cis-regulatory elements controlling GDF6 expression are essential for ear development. J Clin Invest 2021; 130:4213-4217. [PMID: 32369452 DOI: 10.1172/jci136951] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2020] [Accepted: 04/29/2020] [Indexed: 12/15/2022] Open
Abstract
Molecular mechanisms governing the development of the mammalian cochlea, the hearing organ, remain largely unknown. Through genome sequencing in 3 subjects from 2 families with nonsyndromic cochlear aplasia, we identified homozygous 221-kb and 338-kb deletions in a noncoding region on chromosome 8 with an approximately 200-kb overlapping section. Genomic location of the overlapping deleted region started from approximately 350 kb downstream of GDF6, which codes for growth and differentiation factor 6. Otic lineage cells differentiated from induced pluripotent stem cells derived from an affected individual showed reduced expression of GDF6 compared with control cells. Knockout of Gdf6 in a mouse model resulted in cochlear aplasia, closely resembling the human phenotype. We conclude that GDF6 plays a necessary role in early cochlear development controlled by cis-regulatory elements located within an approximately 500-kb region of the genome in humans and that its disruption leads to deafness due to cochlear aplasia.
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Affiliation(s)
- Guney Bademci
- John P. Hussman Institute for Human Genomics, University of Miami Miller School of Medicine, Miami, Florida, USA
| | - Clemer Abad
- John P. Hussman Institute for Human Genomics, University of Miami Miller School of Medicine, Miami, Florida, USA
| | - Filiz B Cengiz
- John P. Hussman Institute for Human Genomics, University of Miami Miller School of Medicine, Miami, Florida, USA
| | - Serhat Seyhan
- John P. Hussman Institute for Human Genomics, University of Miami Miller School of Medicine, Miami, Florida, USA
| | - Armagan Incesulu
- Department of Otolaryngology, Eskisehir Osmangazi University School of Medicine, Eskisehir, Turkey
| | - Shengru Guo
- John P. Hussman Institute for Human Genomics, University of Miami Miller School of Medicine, Miami, Florida, USA
| | - Suat Fitoz
- Department of Diagnostic Radiology, Ankara University School of Medicine, Ankara, Turkey
| | - Emine Ikbal Atli
- Department of Medical Genetics, Faculty of Medicine, Trakya University, Edirne, Turkey
| | - Nicholas C Gosstola
- John P. Hussman Institute for Human Genomics, University of Miami Miller School of Medicine, Miami, Florida, USA
| | - Selma Demir
- Department of Medical Genetics, Faculty of Medicine, Trakya University, Edirne, Turkey
| | - Brett M Colbert
- John P. Hussman Institute for Human Genomics, University of Miami Miller School of Medicine, Miami, Florida, USA.,Medical Scientist Training Program, University of Miami Miller School of Medicine, Miami, Florida, USA
| | - Gozde Cosar Seyhan
- Department of Dermatology, Bakirkoy Sadi Konuk Training and Research Hospital, Istanbul, Turkey
| | - Claire J Sineni
- John P. Hussman Institute for Human Genomics, University of Miami Miller School of Medicine, Miami, Florida, USA
| | - Duygu Duman
- Department of Audiology, Ankara University School of Medicine, Ankara, Turkey
| | - Hakan Gurkan
- Department of Medical Genetics, Faculty of Medicine, Trakya University, Edirne, Turkey
| | - Cynthia C Morton
- Department of Obstetrics and Gynecology, Brigham and Women's Hospital, Boston, Massachusetts, USA.,Harvard Medical School, Boston, Massachusetts, USA.,Program in Medical and Population Genetics, Broad Institute of MIT and Harvard, Cambridge, Massachusetts, USA.,Department of Pathology, Brigham and Women's Hospital, Boston, Massachusetts, USA.,Manchester Centre for Audiology and Deafness, School of Health Sciences, Faculty of Biology, Medicine and Health, Manchester Academic Health Science Centre, University of Manchester, Manchester, United Kingdom
| | - Derek M Dykxhoorn
- John P. Hussman Institute for Human Genomics, University of Miami Miller School of Medicine, Miami, Florida, USA.,John T. Macdonald Foundation Department of Human Genetics, and
| | - Katherina Walz
- John P. Hussman Institute for Human Genomics, University of Miami Miller School of Medicine, Miami, Florida, USA.,John T. Macdonald Foundation Department of Human Genetics, and
| | - Mustafa Tekin
- John P. Hussman Institute for Human Genomics, University of Miami Miller School of Medicine, Miami, Florida, USA.,John T. Macdonald Foundation Department of Human Genetics, and.,Department of Otolaryngology, University of Miami Miller School of Medicine, Miami, Florida, USA
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7
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De Tienda M, Bouthors C, Pejin Z, Glorion C, Wicart P. Multiple synostoses syndrome: Radiological findings and orthopedic management in a single institution cohort. J Pediatr Rehabil Med 2021; 14:361-369. [PMID: 34334433 DOI: 10.3233/prm-200702] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
PURPOSE Multiple synostoses syndrome (MSS) is a rare genetic condition. Classical features consist of joint fusions which notably start at the distal phalanx of the hands and feet with symphalangism progressing proximally to carpal, tarsal, radio-ulnar, and radio-humeral joints, as well as the spine. Usually, genetic testing reveals a mutation of the NOG gene with variable expressivity. The goal was to present the anatomical, functional, and radiological presentations of MSS in a series of patients followed since childhood. METHODS Patients with more than 3 synostoses affecting at least one hand joint were included. When possible, genetic screening was offered. RESULTS A retrospective study was performed from 1972 to 2017 and included 14 patients with a mean follow-up of 18.6 years. Mutation of the NOG protein coding gene was seen in 3 patients. All presented with tarsal synostoses including 9 carpal, 7 elbow, and 2 vertebral fusions. Facial dysmorphia was seen in 6 patients and 3 were hearing-impaired. Surgical treatment of tarsal synostosis was performed in 4 patients. Progressing joint fusions were invariably seen on x-rays amongst adults. CONCLUSION Long radiological follow-up allowed the assessment of MSS progression. Feet deformities resulted in a severe impact on quality of life, and neurological complications secondary to spine fusions warranted performing at least one imaging study in childhood. As there is no treatment of ankylosis, physiotherapy is not recommended. However, surgical arthrodesis for the treatment of pain may have reasonable outcomes.
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Affiliation(s)
- Marine De Tienda
- Universitary Hospital Necker Enfants Malades, Orthopaedic Department, Paris, France
| | - Charlie Bouthors
- Universitary Hospital Kremlin Bicêtre, Orthopaedic Department, Le Kremlin-Bicêtre, France
| | - Zagorha Pejin
- Universitary Hospital Necker Enfants Malades, Orthopaedic Department, Paris, France
| | - Christophe Glorion
- Universitary Hospital Necker Enfants Malades, Orthopaedic Department, Paris, France
| | - Philippe Wicart
- Universitary Hospital Necker Enfants Malades, Orthopaedic Department, Paris, France
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8
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Martens H, Hennies I, Getwan M, Christians A, Weiss AC, Brand F, Gjerstad AC, Christians A, Gucev Z, Geffers R, Seeman T, Kispert A, Tasic V, Bjerre A, Lienkamp SS, Haffner D, Weber RG. Rare heterozygous GDF6 variants in patients with renal anomalies. Eur J Hum Genet 2020; 28:1681-1693. [PMID: 32737436 PMCID: PMC7784874 DOI: 10.1038/s41431-020-0678-9] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2020] [Revised: 06/05/2020] [Accepted: 06/15/2020] [Indexed: 01/22/2023] Open
Abstract
Although over 50 genes are known to cause renal malformation if mutated, the underlying genetic basis, most easily identified in syndromic cases, remains unsolved in most patients. In search of novel causative genes, whole-exome sequencing in a patient with renal, i.e., crossed fused renal ectopia, and extrarenal, i.e., skeletal, eye, and ear, malformations yielded a rare heterozygous variant in the GDF6 gene encoding growth differentiation factor 6, a member of the BMP family of ligands. Previously, GDF6 variants were reported to cause pleiotropic defects including skeletal, e.g., vertebral, carpal, tarsal fusions, and ocular, e.g., microphthalmia and coloboma, phenotypes. To assess the role of GDF6 in the pathogenesis of renal malformation, we performed targeted sequencing in 193 further patients identifying rare GDF6 variants in two cases with kidney hypodysplasia and extrarenal manifestations. During development, gdf6 was expressed in the pronephric tubule of Xenopus laevis, and Gdf6 expression was observed in the ureteric tree of the murine kidney by RNA in situ hybridization. CRISPR/Cas9-derived knockout of Gdf6 attenuated migration of murine IMCD3 cells, an effect rescued by expression of wild-type but not mutant GDF6, indicating affected variant function regarding a fundamental developmental process. Knockdown of gdf6 in Xenopus laevis resulted in impaired pronephros development. Altogether, we identified rare heterozygous GDF6 variants in 1.6% of all renal anomaly patients and 5.4% of renal anomaly patients additionally manifesting skeletal, ocular, or auricular abnormalities, adding renal hypodysplasia and fusion to the phenotype spectrum of GDF6 variant carriers and suggesting an involvement of GDF6 in nephrogenesis.
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Affiliation(s)
- Helge Martens
- Department of Human Genetics, Hannover Medical School, 30625, Hannover, Germany
| | - Imke Hennies
- Department of Pediatric Kidney, Liver and Metabolic Diseases, Hannover Medical School, 30625, Hannover, Germany
| | - Maike Getwan
- Department of Medicine, Renal Division, University Medical Center Freiburg, Faculty of Medicine, University of Freiburg, 79110, Freiburg, Germany.,Institute of Anatomy and Zurich Center for Integrative Human Physiology (ZIHP), University of Zurich, 8057, Zurich, Switzerland
| | - Anne Christians
- Department of Human Genetics, Hannover Medical School, 30625, Hannover, Germany
| | - Anna-Carina Weiss
- Institute of Molecular Biology, Hannover Medical School, 30625, Hannover, Germany
| | - Frank Brand
- Department of Human Genetics, Hannover Medical School, 30625, Hannover, Germany
| | - Ann Christin Gjerstad
- Division of Paediatric and Adolescent Medicine, Oslo University Hospital, 0424, Oslo, Norway
| | - Arne Christians
- Department of Neuropathology, Institute of Pathology, Hannover Medical School, 30625, Hannover, Germany
| | - Zoran Gucev
- Medical Faculty Skopje, University Children's Hospital, 1000, Skopje, North Macedonia
| | - Robert Geffers
- Genome Analytics Research Group, Helmholtz Centre for Infection Research, 38124, Braunschweig, Germany
| | - Tomáš Seeman
- Department of Paediatrics and Transplantation Center, University Hospital Motol, Second Faculty of Medicine, Charles University, 150 06, Prague, Czech Republic
| | - Andreas Kispert
- Institute of Molecular Biology, Hannover Medical School, 30625, Hannover, Germany
| | - Velibor Tasic
- Medical Faculty Skopje, University Children's Hospital, 1000, Skopje, North Macedonia
| | - Anna Bjerre
- Division of Paediatric and Adolescent Medicine, Oslo University Hospital, 0424, Oslo, Norway
| | - Soeren S Lienkamp
- Department of Medicine, Renal Division, University Medical Center Freiburg, Faculty of Medicine, University of Freiburg, 79110, Freiburg, Germany.,Institute of Anatomy and Zurich Center for Integrative Human Physiology (ZIHP), University of Zurich, 8057, Zurich, Switzerland
| | - Dieter Haffner
- Department of Pediatric Kidney, Liver and Metabolic Diseases, Hannover Medical School, 30625, Hannover, Germany
| | - Ruthild G Weber
- Department of Human Genetics, Hannover Medical School, 30625, Hannover, Germany.
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Drage Berentsen R, Haukanes BI, Júlíusson PB, Rosendahl K, Houge G. A Novel GDF6 Mutation in a Family with Multiple Synostoses Syndrome without Hearing Loss. Mol Syndromol 2018; 9:228-234. [PMID: 30733656 DOI: 10.1159/000492418] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/07/2018] [Indexed: 11/19/2022] Open
Abstract
A 4-generation family with multiple synostoses syndrome type 4 (SYNS4) is reported, the third family identified so far. The phenotype segregated with a previously undescribed Asn399Lys (c.1197C>A) substitution in GDF6. N399 is part of a hydrophobic pocket critical for binding the BMP/GDF antagonist noggin. The N399K substitution renders GDF6 more similar to noggin-resistant members of the BMP family, namely GDF2 and BMP10, both of which contain lysine in the corresponding position. To further define the SYNS4 phenotype, we examined 6 of 9 affected family members. The phenotype was carpal and tarsal synostoses with painful feet after walking, but the condition could also be asymptomatic. Interestingly, unlike the previous SYNS4 families, the family presented here has no history of hearing loss, and a 73-year-old mutation carrier had normal audiometry for his age. Based on structure modelling, BMPR2 binding should not be affected by the GDF6-N399K substitution, unlike the S429R and Y444N mutations found in the 2 other families. Hypothetically, this difference may be related to lack of hearing loss.
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Affiliation(s)
| | - Bjørn I Haukanes
- Department of Medical Genetics, Haukeland University Hospital, Bergen, Norway
| | - Pétur B Júlíusson
- Department of Pediatrics, Haukeland University Hospital, Bergen, Norway.,Department of Department of Clinical Science, University of Bergen, Bergen, Norway
| | - Karen Rosendahl
- Department of Radiology, Haukeland University Hospital, Bergen, Norway
| | - Gunnar Houge
- Department of Medical Genetics, Haukeland University Hospital, Bergen, Norway
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