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Fukushima K, Parthasarathy P, Wade EM, Morgan T, Gowrishankar K, Markie DM, Robertson SP. Intragenic Deletions in FLNB Are Part of the Mutational Spectrum Causing Spondylocarpotarsal Synostosis Syndrome. Genes (Basel) 2021; 12:528. [PMID: 33916386 DOI: 10.3390/genes12040528] [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] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2021] [Revised: 03/25/2021] [Accepted: 04/01/2021] [Indexed: 11/16/2022] Open
Abstract
Spondylocarpotarsal synostosis syndrome (SCT) is characterized by vertebral fusions, a disproportionately short stature, and synostosis of carpal and tarsal bones. Pathogenic variants in FLNB, MYH3, and possibly in RFLNA, have been reported to be responsible for this condition. Here, we present two unrelated individuals presenting with features typical of SCT in which Sanger sequencing combined with whole genome sequencing identified novel, homozygous intragenic deletions in FLNB (c.1346-1372_1941+389del and c.3127-353_4223-1836del). Both deletions remove several consecutive exons and are predicted to result in a frameshift. To our knowledge, this is the first time that large structural variants in FLNB have been reported in SCT, and thus our findings add to the classes of variation that can lead to this disorder. These cases highlight the need for copy number sensitive methods to be utilized in order to be comprehensive in the search for a molecular diagnosis in individuals with a clinical diagnosis of SCT.
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Hakonen AH, Lehtonen J, Kivirikko S, Keski-Filppula R, Moilanen J, Kivisaari R, Almusa H, Jakkula E, Saarela J, Avela K, Aittomäki K. Recessive MYH3 variants cause "Contractures, pterygia, and variable skeletal fusions syndrome 1B" mimicking Escobar variant multiple pterygium syndrome. Am J Med Genet A 2020; 182:2605-2610. [PMID: 32902138 DOI: 10.1002/ajmg.a.61836] [Citation(s) in RCA: 3] [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] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2020] [Revised: 07/06/2020] [Accepted: 08/01/2020] [Indexed: 11/09/2022]
Abstract
The multiple pterygium syndromes (MPS) are rare disorders with disease severity ranging from lethal to milder forms. The nonlethal Escobar variant MPS (EVMPS) is characterized by multiple pterygia and arthrogryposis, as well as various additional features including congenital anomalies. The genetic etiology of EVMPS is heterogeneous and the diagnosis has been based either on the detection of pathogenic CHRNG variants (~23% of patients), or suggestive clinical features. We describe four patients with a clinical suspicion of EVMPS who manifested with multiple pterygia, mild flexion contractures of several joints, and vertebral anomalies. We revealed recessively inherited MYH3 variants as the underlying cause in all patients: two novel variants, c.1053C>G, p.(Tyr351Ter) and c.3102+5G>C, as compound heterozygous with the hypomorphic MYH3 variant c.-9+1G>A. Recessive MYH3 variants have been previously associated with spondylocarpotarsal synostosis syndrome. Our findings now highlight multiple pterygia as an important feature in patients with recessive MYH3 variants. Based on all patients with recessive MYH3 variants reported up to date, we consider that this disease entity should be designated as "Contractures, pterygia, and variable skeletal fusions syndrome 1B," as recently suggested by OMIM. Our findings underline the importance of analyzing MYH3 in the differential diagnosis of EVMPS, particularly as the hypomorphic MYH3 variant might remain undetected by routine exome sequencing.
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Affiliation(s)
- Anna H Hakonen
- Department of Clinical Genetics, HUSLAB, HUS Diagnostic Center, University of Helsinki and Helsinki University Hospital, Helsinki, Finland
| | - Johanna Lehtonen
- Institute for Molecular Medicine Finland, FIMM, University of Helsinki, Helsinki, Finland.,Folkhälsan Research Center, Helsinki, Finland
| | - Sirpa Kivirikko
- Department of Clinical Genetics, HUSLAB, HUS Diagnostic Center, University of Helsinki and Helsinki University Hospital, Helsinki, Finland
| | - Riikka Keski-Filppula
- Department of Clinical Genetics, Oulu University Hospital, Medical Research Center Oulu and PEDEGO Research Unit, University of Oulu, Oulu, Finland
| | - Jukka Moilanen
- Department of Clinical Genetics, Oulu University Hospital, Medical Research Center Oulu and PEDEGO Research Unit, University of Oulu, Oulu, Finland
| | - Reetta Kivisaari
- HUS Medical Imaging Center, Children's Hospital, University of Helsinki and Helsinki University Hospital, Helsinki, Finland
| | - Henrikki Almusa
- Institute for Molecular Medicine Finland, FIMM, University of Helsinki, Helsinki, Finland
| | - Eveliina Jakkula
- Department of Clinical Genetics, HUSLAB, HUS Diagnostic Center, University of Helsinki and Helsinki University Hospital, Helsinki, Finland
| | - Janna Saarela
- Institute for Molecular Medicine Finland, FIMM, University of Helsinki, Helsinki, Finland.,Centre for Molecular Medicine Norway (NCMM), University of Oslo, Oslo, Norway.,HUSLAB, HUS Diagnostic Center, University of Helsinki and Helsinki University Hospital, Helsinki, Finland
| | - Kristiina Avela
- Department of Clinical Genetics, HUSLAB, HUS Diagnostic Center, University of Helsinki and Helsinki University Hospital, Helsinki, Finland
| | - Kristiina Aittomäki
- Department of Clinical Genetics, HUSLAB, HUS Diagnostic Center, University of Helsinki and Helsinki University Hospital, Helsinki, Finland
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Salian S, Shukla A, Shah H, Bhat SN, Bhat VR, Nampoothiri S, Shenoy R, Phadke SR, Hariharan SV, Girisha KM. Seven additional families with spondylocarpotarsal synostosis syndrome with novel biallelic deleterious variants in FLNB. Clin Genet 2018; 94:159-164. [PMID: 29566257 DOI: 10.1111/cge.13252] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [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: 01/18/2018] [Revised: 03/15/2018] [Accepted: 03/17/2018] [Indexed: 02/01/2023]
Abstract
The location and/or type of variants in FLNB result in a spectrum of osteochondrodysplasias ranging from mild forms, like spondylocarpotarsal synostosis syndrome and Larsen syndrome, to severe perinatal lethal forms, such as atelosteogenesis I and III and Boomerang dysplasia. Spondylocarpotarsal synostosis syndrome is characterized by disproportionate short stature, vertebral anomalies and fusion of carpal and tarsal bones. Biallelic loss-of-function variants in FLNB are known to cause spondylocarpotarsal synostosis syndrome and 9 families and 9 pathogenic variants have been reported so far. We report clinical features of 10 additional patients from 7 families with spondylocarpotarsal synostosis syndrome due to 7 novel deleterious variants in FLNB, thus expanding the clinical and molecular repertoire of spondylocarpotarsal synostosis syndrome. Our report validates key clinical (fused thoracic vertebrae and carpal and tarsal coalition) and molecular (truncating variants in FLNB) characteristics of this condition.
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Affiliation(s)
- S Salian
- Department of Medical Genetics, Kasturba Medical College, Manipal Academy of Higher Education, Manipal, Karnataka, India
| | - A Shukla
- Department of Medical Genetics, Kasturba Medical College, Manipal Academy of Higher Education, Manipal, Karnataka, India
| | - H Shah
- Department of Orthopedics, Kasturba Medical College, Manipal Academy of Higher Education, Manipal, Karnataka, India
| | - S N Bhat
- Department of Orthopedics, Kasturba Medical College, Manipal Academy of Higher Education, Manipal, Karnataka, India
| | - V R Bhat
- Department of Medical Genetics, Kasturba Medical College, Manipal Academy of Higher Education, Manipal, Karnataka, India
| | - S Nampoothiri
- Department of Pediatric Genetics, Amrita Institute of Medical Sciences and Research Centre, Cochin, Kerala, India
| | - R Shenoy
- Department of Pediatrics, KS Hegde Medical Academy, Mangalore, Karnataka, India
| | - S R Phadke
- Department of Medical Genetics, Sanjay Gandhi Postgraduate Institute of Medical Sciences, Lucknow, Uttar Pradesh, India
| | - S V Hariharan
- Department of Pediatrics, Sree Avittom Thirunal Hospital, Government Medical College, Trivandrum, Kerala, India
| | - K M Girisha
- Department of Medical Genetics, Kasturba Medical College, Manipal Academy of Higher Education, Manipal, Karnataka, India
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Yang CF, Wang CH, Siong H'ng W, Chang CP, Lin WD, Chen YT, Wu JY, Tsai FJ. Filamin B Loss-of-Function Mutation in Dimerization Domain Causes Autosomal-Recessive Spondylocarpotarsal Synostosis Syndrome with Rib Anomalies. Hum Mutat 2017; 38:540-547. [PMID: 28145000 DOI: 10.1002/humu.23186] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2016] [Accepted: 01/23/2017] [Indexed: 02/06/2023]
Abstract
Spondylocarpotarsal synostosis syndrome (SCT) is a distinct group of disorders characterized by short stature, disrupted vertebral segmentation with vertebral fusion, scoliosis, lordosis, carpal/tarsal synostosis, and lack of rib anomalies. Mutations in filamin B (FLNB) and MYH3 have been reported for autosomal-recessive and autosomal-dominant SCT, respectively. We present a family with two patients suffering from autosomal-recessive SCT with rib anomalies, including malalignment, crowding, and uneven size and shape of ribs. Whole-exome sequencing revealed a novel p.S2542Lfs* 82 (c.7621dup) frameshift mutation in FLNB. This frameshift mutation lies in the C-terminal-most domain involved in FLNB dimerization and resulted in a 20-residue elongation, with complete familial segregation and absence in 376 normal controls. The mutant p.S2542Lfs* 82 FLNB demonstrated a complete loss of ability to form a functional dimer in transiently transfected HEK293T cells. The p.S2542Lfs* 82 mutation also led to significantly reduced protein levels and accumulation of the mutant protein in the Golgi apparatus. This is the first identified mutation in the dimerization domain of FLNB. This loss-of-function frameshift mutation in FLNB causes autosomal-recessive SCT with rarely reported rib anomalies. This report demonstrates the involvement of rib anomaly in SCT and its causative mutation in the dimerization domain of FLNB.
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Affiliation(s)
- Chi-Fan Yang
- Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan
| | - Chung-Hsing Wang
- Department of Genetics and Metabolism, Children's Hospital of China Medical University, Taichung, Taiwan
- School of Medicine, China Medical University, Taichung, Taiwan
| | - Weng Siong H'ng
- Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan
| | - Chun-Ping Chang
- Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan
| | - Wei-De Lin
- Department of Medical Genetics, China Medical University Hospital, Taichung, Taiwan
- School of Post Baccalaureate Chinese Medicine, China Medical University, Taichung, Taiwan
| | - Yuan-Tsong Chen
- Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan
| | - Jer-Yuarn Wu
- Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan
| | - Fuu-Jen Tsai
- Department of Medical Genetics, China Medical University Hospital, Taichung, Taiwan
- Department of Medical Research, China Medical University Hospital, Taichung, Taiwan
- School of Chinese Medicine, China Medical University, Taichung, Taiwan
- Division of Pediatric Genetics, Endocrinology & Metabolism, China Medical University Children's Hospital, Taichung, Taiwan
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