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Grosz BR, Parmar JM, Ellis M, Bryen S, Simons C, Reis ALM, Stevanovski I, Deveson IW, Nicholson G, Laing N, Wallis M, Ravenscroft G, Kumar KR, Vucic S, Kennerson ML. A deep intronic variant in MME causes autosomal recessive Charcot-Marie-Tooth neuropathy through aberrant splicing. J Peripher Nerv Syst 2024; 29:262-274. [PMID: 38860315 DOI: 10.1111/jns.12637] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2024] [Revised: 05/26/2024] [Accepted: 05/28/2024] [Indexed: 06/12/2024]
Abstract
BACKGROUND Loss-of-function variants in MME (membrane metalloendopeptidase) are a known cause of recessive Charcot-Marie-Tooth Neuropathy (CMT). A deep intronic variant, MME c.1188+428A>G (NM_000902.5), was identified through whole genome sequencing (WGS) of two Australian families with recessive inheritance of axonal CMT using the seqr platform. MME c.1188+428A>G was detected in a homozygous state in Family 1, and in a compound heterozygous state with a known pathogenic MME variant (c.467del; p.Pro156Leufs*14) in Family 2. AIMS We aimed to determine the pathogenicity of the MME c.1188+428A>G variant through segregation and splicing analysis. METHODS The splicing impact of the deep intronic MME variant c.1188+428A>G was assessed using an in vitro exon-trapping assay. RESULTS The exon-trapping assay demonstrated that the MME c.1188+428A>G variant created a novel splice donor site resulting in the inclusion of an 83 bp pseudoexon between MME exons 12 and 13. The incorporation of the pseudoexon into MME transcript is predicted to lead to a coding frameshift and premature termination codon (PTC) in MME exon 14 (p.Ala397ProfsTer47). This PTC is likely to result in nonsense mediated decay (NMD) of MME transcript leading to a pathogenic loss-of-function. INTERPRETATION To our knowledge, this is the first report of a pathogenic deep intronic MME variant causing CMT. This is of significance as deep intronic variants are missed using whole exome sequencing screening methods. Individuals with CMT should be reassessed for deep intronic variants, with splicing impacts being considered in relation to the potential pathogenicity of variants.
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Affiliation(s)
- Bianca R Grosz
- Northcott Neuroscience Laboratory, ANZAC Research Institute, Sydney, New South Wales, Australia
- The University of Sydney, Camperdown, New South Wales, Australia
| | - Jevin M Parmar
- Rare Disease Genetics and Functional Genomics Research Group, Harry Perkins Institute of Medical Research, QEII Medical Centre, Nedlands, Western Australia, Australia
- Centre for Medical Research, Faculty of Health and Medical Sciences, The University of Western Australia, Perth, Western Australia, Australia
| | - Melina Ellis
- Northcott Neuroscience Laboratory, ANZAC Research Institute, Sydney, New South Wales, Australia
- The University of Sydney, Camperdown, New South Wales, Australia
| | - Samantha Bryen
- Centre for Population Genomics, Garvan Institute of Medical Research, and UNSW Sydney, Sydney, New South Wales, Australia
- Centre for Population Genomics, Murdoch Children's Research Institute, Melbourne, Victoria, Australia
| | - Cas Simons
- Centre for Population Genomics, Garvan Institute of Medical Research, and UNSW Sydney, Sydney, New South Wales, Australia
- Centre for Population Genomics, Murdoch Children's Research Institute, Melbourne, Victoria, Australia
| | - Andre L M Reis
- Centre for Population Genomics, Garvan Institute of Medical Research, and UNSW Sydney, Sydney, New South Wales, Australia
- Genomics and Inherited Disease Program, Garvan Institute of Medical Research, Sydney, New South Wales, Australia
- Faculty of Medicine, University of New South Wales, Sydney, New South Wales, Australia
| | - Igor Stevanovski
- Centre for Population Genomics, Garvan Institute of Medical Research, and UNSW Sydney, Sydney, New South Wales, Australia
- Genomics and Inherited Disease Program, Garvan Institute of Medical Research, Sydney, New South Wales, Australia
| | - Ira W Deveson
- Centre for Population Genomics, Garvan Institute of Medical Research, and UNSW Sydney, Sydney, New South Wales, Australia
- Genomics and Inherited Disease Program, Garvan Institute of Medical Research, Sydney, New South Wales, Australia
- Faculty of Medicine, University of New South Wales, Sydney, New South Wales, Australia
| | - Garth Nicholson
- The University of Sydney, Camperdown, New South Wales, Australia
- Molecular Medicine Laboratory and Neurology Department, Concord Repatriation General Hospital, Concord, New South Wales, Australia
| | - Nigel Laing
- Rare Disease Genetics and Functional Genomics Research Group, Harry Perkins Institute of Medical Research, QEII Medical Centre, Nedlands, Western Australia, Australia
| | - Mathew Wallis
- Tasmanian Clinical Genetics Service, Tasmanian Health Service, Hobart, Australia
- School of Medicine and Menzies Institute for Medical Research, University of Tasmania, Hobart, Australia
| | - Gianina Ravenscroft
- Rare Disease Genetics and Functional Genomics Research Group, Harry Perkins Institute of Medical Research, QEII Medical Centre, Nedlands, Western Australia, Australia
| | - Kishore R Kumar
- The University of Sydney, Camperdown, New South Wales, Australia
- Molecular Medicine Laboratory and Neurology Department, Concord Repatriation General Hospital, Concord, New South Wales, Australia
- Translational Neurogenomics Group, Genomic and Inherited Disease Program, The Garvan Institute of Medical Research, Darlinghurst, New South Wales, Australia
- St Vincent's Healthcare Campus, Faculty of Medicine, UNSW Sydney, Darlinghurst, New South Wales, Australia
| | - Steve Vucic
- The University of Sydney, Camperdown, New South Wales, Australia
- Brain and Nerve Research Centre, The University of Sydney, Sydney, New South Wales, Australia
| | - Marina L Kennerson
- Northcott Neuroscience Laboratory, ANZAC Research Institute, Sydney, New South Wales, Australia
- The University of Sydney, Camperdown, New South Wales, Australia
- Molecular Medicine Laboratory and Neurology Department, Concord Repatriation General Hospital, Concord, New South Wales, Australia
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Uncini A, Cavallaro T, Fabrizi GM, Manganelli F, Vallat JM. Conduction slowing, conduction block and temporal dispersion in demyelinating, dysmyelinating and axonal neuropathies: Electrophysiology meets pathology. J Peripher Nerv Syst 2024; 29:135-160. [PMID: 38600691 DOI: 10.1111/jns.12625] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2024] [Revised: 03/02/2024] [Accepted: 03/28/2024] [Indexed: 04/12/2024]
Abstract
Nerve conduction studies are usually the first diagnostic step in peripheral nerve disorders and their results are the basis for planning further investigations. However, there are some commonplaces in the interpretation of electrodiagnostic findings in peripheral neuropathies that, although useful in the everyday practice, may be misleading: (1) conduction block and abnormal temporal dispersion are distinctive features of acquired demyelinating disorders; (2) hereditary neuropathies are characterized by uniform slowing of conduction velocity; (3) axonal neuropathies are simply diagnosed by reduced amplitude of motor and sensory nerve action potentials with normal or slightly slow conduction velocity. In this review, we reappraise the occurrence of uniform and non-uniform conduction velocity slowing, conduction block and temporal dispersion in demyelinating, dysmyelinating and axonal neuropathies attempting, with a translational approach, a correlation between electrophysiological and pathological features as derived from sensory nerve biopsy in patients and animal models. Additionally, we provide some hints to navigate in this complex field.
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Affiliation(s)
- Antonino Uncini
- Department of Neurosciences, Imaging and Clinical Sciences, University "G. d'Annunzio", Chieti-Pescara, Italy
| | - Tiziana Cavallaro
- Department of Neurosciences, Biomedicine, and Movement Sciences, University of Verona, Verona, Italy
| | - Gian Maria Fabrizi
- Department of Neurosciences, Biomedicine, and Movement Sciences, University of Verona, Verona, Italy
| | - Fiore Manganelli
- Department of Neurosciences, Reproductive Sciences and Odontostomatology, University of Naples "Federico II", Naples, Italy
| | - Jean-Michel Vallat
- Department of Neurology, National Reference Center for "Rare Peripheral Neuropathies", CHU Dupuytren, Limoges, France
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Record CJ, Skorupinska M, Laura M, Rossor AM, Pareyson D, Pisciotta C, Feely SME, Lloyd TE, Horvath R, Sadjadi R, Herrmann DN, Li J, Walk D, Yum SW, Lewis RA, Day J, Burns J, Finkel RS, Saporta MA, Ramchandren S, Weiss MD, Acsadi G, Fridman V, Muntoni F, Poh R, Polke JM, Zuchner S, Shy ME, Scherer SS, Reilly MM. Genetic analysis and natural history of Charcot-Marie-Tooth disease CMTX1 due to GJB1 variants. Brain 2023; 146:4336-4349. [PMID: 37284795 PMCID: PMC10545504 DOI: 10.1093/brain/awad187] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2023] [Revised: 05/05/2023] [Accepted: 05/20/2023] [Indexed: 06/08/2023] Open
Abstract
Charcot-Marie-Tooth disease (CMT) due to GJB1 variants (CMTX1) is the second most common form of CMT. It is an X-linked disorder characterized by progressive sensory and motor neuropathy with males affected more severely than females. Many reported GJB1 variants remain classified as variants of uncertain significance (VUS). In this large, international, multicentre study we prospectively collected demographic, clinical and genetic data on patients with CMT associated with GJB1 variants. Pathogenicity for each variant was defined using adapted American College of Medical Genetics criteria. Baseline and longitudinal analyses were conducted to study genotype-phenotype correlations, to calculate longitudinal change using the CMT Examination Score (CMTES), to compare males versus females, and pathogenic/likely pathogenic (P/LP) variants versus VUS. We present 387 patients from 295 families harbouring 154 variants in GJB1. Of these, 319 patients (82.4%) were deemed to have P/LP variants, 65 had VUS (16.8%) and three benign variants (0.8%; excluded from analysis); an increased proportion of patients with P/LP variants compared with using ClinVar's classification (74.6%). Male patients (166/319, 52.0%, P/LP only) were more severely affected at baseline. Baseline measures in patients with P/LP variants and VUS showed no significant differences, and regression analysis suggested the disease groups were near identical at baseline. Genotype-phenotype analysis suggested c.-17G>A produces the most severe phenotype of the five most common variants, and missense variants in the intracellular domain are less severe than other domains. Progression of disease was seen with increasing CMTES over time up to 8 years follow-up. Standard response mean (SRM), a measure of outcome responsiveness, peaked at 3 years with moderate responsiveness [change in CMTES (ΔCMTES) = 1.3 ± 2.6, P = 0.00016, SRM = 0.50]. Males and females progressed similarly up to 8 years, but baseline regression analysis suggested that over a longer period, females progress more slowly. Progression was most pronounced for mild phenotypes (CMTES = 0-7; 3-year ΔCMTES = 2.3 ± 2.5, P = 0.001, SRM = 0.90). Enhanced variant interpretation has yielded an increased proportion of GJB1 variants classified as P/LP and will aid future variant interpretation in this gene. Baseline and longitudinal analysis of this large cohort of CMTX1 patients describes the natural history of the disease including the rate of progression; CMTES showed moderate responsiveness for the whole group at 3 years and higher responsiveness for the mild group at 3, 4 and 5 years. These results have implications for patient selection for upcoming clinical trials.
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Affiliation(s)
- Christopher J Record
- Department of Neuromuscular Diseases, UCL Queen Square Institute of Neurology, London, WC1N 3BG, UK
| | - Mariola Skorupinska
- Department of Neuromuscular Diseases, UCL Queen Square Institute of Neurology, London, WC1N 3BG, UK
| | - Matilde Laura
- Department of Neuromuscular Diseases, UCL Queen Square Institute of Neurology, London, WC1N 3BG, UK
| | - Alexander M Rossor
- Department of Neuromuscular Diseases, UCL Queen Square Institute of Neurology, London, WC1N 3BG, UK
| | - Davide Pareyson
- Department of Clinical Neurosciences, Fondazione IRCCS Istituto Neurologico Carlo Besta, 20133 Milan, Italy
| | - Chiara Pisciotta
- Department of Clinical Neurosciences, Fondazione IRCCS Istituto Neurologico Carlo Besta, 20133 Milan, Italy
| | - Shawna M E Feely
- Department of Neurology, University of Iowa Carver College of Medicine, Iowa City, IA 52242, USA
| | - Thomas E Lloyd
- Departments of Neurology and Neuroscience, John Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Rita Horvath
- Department of Clinical Neurosciences, University of Cambridge, Cambridge, CB2 0PY, UK
| | - Reza Sadjadi
- Department of Neurology, Massachusetts General Hospital, Boston, MA 02114, USA
| | - David N Herrmann
- Department of Neurology, University of Rochester, Rochester, NY 14618, USA
| | - Jun Li
- Department of Neurology, Houston Methodist Hospital, Houston, TX 77030, USA
| | - David Walk
- Department of Neurology, University of Minnesota, Minneapolis, MN 55455, USA
| | - Sabrina W Yum
- Department of Neurology, The Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA 19104, USA
- Department of Neurology, Children’s Hospital of Philadelphia, Philadelphia, PA 19104, USA
| | - Richard A Lewis
- Department of Neurology, Cedars-Sinai Medical Center, Los Angeles, CA 90048, USA
| | - John Day
- Department of Neurology, Stanford University, Stanford, CA 94304, USA
| | - Joshua Burns
- University of Sydney School of Health Sciences, Faculty of Medicine and Health; Paediatric Gait Analysis Service of New South Wales, Sydney Children’s Hospitals Network, Sydney, 2145Australia
| | - Richard S Finkel
- Department of Neurology, Nemours Children’s Hospital, Orlando, FL 32827, USA
| | - Mario A Saporta
- Department of Neurology, University of Miami Miller School of Medicine, Miami, FL 33136, USA
| | - Sindhu Ramchandren
- Department of Neurology, Wayne State University, Detroit, MI 48201, USA
- The Janssen Pharmaceutical Companies of Johnson & Johnson, Titusville, NJ 08560, USA
| | - Michael D Weiss
- Department of Neurology, University of Washington, Seattle, WA, 98195USA
| | - Gyula Acsadi
- Connecticut Children’s Medical Center, Hartford, CT 06106, USA
| | - Vera Fridman
- Department of Neurology, University of Colorado Denver School of Medicine, Aurora, CO 80045, USA
| | - Francesco Muntoni
- The Dubowitz Neuromuscular Centre, NIHR Great Ormond Street Hospital Biomedical Research Centre, Great Ormond Street Institute of Child Health University College London, and Great Ormond Street Hospital Trust, London, WC1N 1EH, UK
| | - Roy Poh
- Neurogenetics Laboratory, National Hospital for Neurology and Neurosurgery, London, WC1N 3BG, UK
| | - James M Polke
- Neurogenetics Laboratory, National Hospital for Neurology and Neurosurgery, London, WC1N 3BG, UK
| | - Stephan Zuchner
- Dr. John T. Macdonald Foundation Department of Human Genetics and John P. Hussman Institute for Human Genomics, University of Miami Miller School of Medicine, Miami, FL 33136, USA
| | - Michael E Shy
- Department of Neurology, University of Iowa Carver College of Medicine, Iowa City, IA 52242, USA
| | - Steven S Scherer
- Department of Neurology, The Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Mary M Reilly
- Department of Neuromuscular Diseases, UCL Queen Square Institute of Neurology, London, WC1N 3BG, UK
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Li M, Yin M, Yang L, Chen Z, Du P, Sun L, Chen J. A novel splicing mutation in 5'UTR of GJB1 causes X-linked Charcot-Marie-tooth disease. Mol Genet Genomic Med 2023; 11:e2108. [PMID: 36394156 PMCID: PMC10009907 DOI: 10.1002/mgg3.2108] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2022] [Revised: 11/08/2022] [Accepted: 11/09/2022] [Indexed: 11/18/2022] Open
Abstract
BACKGROUND Charcot-Marie-Tooth (CMT) disease is the most frequent hereditary motor sensory neurological disease. GJB1 gene is the second most frequent cause of CMT, accounting for approximately 10% of CMT cases worldwide. We identified a large Han family with X-linked CMT disease. METHODS In this study, the probands and his mother underwent electrophysiological examinations and other family members were assessed retrospectively. Whole-exome sequencing, Sanger sequencing, and SNP array linkage analysis were performed to find and confirm the variant. The functional effect of the identified variant was further investigated in HEK293 cells and MCF-7 cells by minigene splicing assay. RESULTS The affected individuals had some clinical symptoms including symmetric atrophy and progressive weakness of the distal muscles in their twenties. Electrophysiological examinations result in peripheral nerve injury of the upper and lower limbs. Whole-exome sequencing identified a novel hemizygous deletion mutation (NM_000166: c.-16-8_-14del) in the GJB1 gene. SNP array linkage analysis and co-segregation analysis confirmed this mutation. Minigene splicing assay verified that this mutation leads to the activation of cryptic splicing sites in exon 2 which results in the deletion of exon 2. CONCLUSION Our study provides theoretical guidance for prenatal diagnosis and subsequent fertility of this family. This result expands the spectrum of mutations in GJB1 known to be associated with CMTX and contributes to the diagnosis of CMT and clinical genetic counseling.
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Affiliation(s)
- MeiYi Li
- Center of Reproductive Medicine, Guangzhou Women and Children's Medical Center, Guangzhou Medical University, Guangzhou, China
| | - Minna Yin
- Center of Reproductive Medicine, Guangzhou Women and Children's Medical Center, Guangzhou Medical University, Guangzhou, China
| | - Li Yang
- Center of Reproductive Medicine, Guangzhou Women and Children's Medical Center, Guangzhou Medical University, Guangzhou, China
| | - Zhiheng Chen
- Center of Reproductive Medicine, Guangzhou Women and Children's Medical Center, Guangzhou Medical University, Guangzhou, China
| | - Peng Du
- Genetic Testing Center, Guangzhou Women and Children's Medical Center, Guangzhou Medical University, Guangzhou, China
| | - Ling Sun
- Center of Reproductive Medicine, Guangzhou Women and Children's Medical Center, Guangzhou Medical University, Guangzhou, China
| | - Juan Chen
- Center of Reproductive Medicine, Guangzhou Women and Children's Medical Center, Guangzhou Medical University, Guangzhou, China
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Skorodumova LO, Davydenko KA, Filatova AY, Skoblov MY, Kulemin NA, Khadzhieva MB, Zakharova ES, Gordeeva VD, Smetanina NS, Fedyushkina IV, Anastasevich LA, Larin SS. Splice-site variant in the RPS7 5'-UTR leads to a decrease in the mRNA level and development of Diamond-Blackfan anemia. Clin Genet 2023; 103:93-96. [PMID: 36057918 DOI: 10.1111/cge.14221] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2022] [Revised: 08/11/2022] [Accepted: 08/23/2022] [Indexed: 12/13/2022]
Abstract
Diamond-Blackfan anemia (DBA) is an inherited bone marrow failure syndrome characterized by erythroid aplasia. Pathogenic variants in ribosomal protein (RP) genes, GATA1, TSR2, and EPO, are considered to be the etiology of DBA. Variants in 5'-untranslated regions (UTRs) of these genes are poorly studied and can complicate the variant interpretation. We investigated the functional consequences NM_001011.4:c.-19 + 1G > T variant in the donor splice-site of the RPS7 5'-UTR. This variant was found in a family where two sons with DBA were carriers. Father, who also had this variant, developed myelodysplastic syndrome, which caused his death. Search for candidate causal variants and copy number variations in DBA-associated genes left RPS7 variant as the best candidate. Trio whole exome sequencing analysis revealed no pathogenic variants in other genes. Functional analysis using luciferase expression system revealed that this variant leads to disruption of splicing. Also, a decrease in the levels of mRNA and protein expression was detected. In conclusion, the established consequences of 5'-UTR splice-site variant c.-19 + 1G > T in the RPS7 gene provide evidence that it is likely pathogenic.
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Affiliation(s)
- Liubov O Skorodumova
- Dmitry Rogachev National Research Center of Pediatric Hematology, Oncology and Immunology, Moscow, Russian Federation.,Federal Research and Clinical Center of Physical-Chemical Medicine of Federal Medical Biological Agency, Moscow, Russian Federation
| | | | | | | | - Nikolay A Kulemin
- Federal Research and Clinical Center of Physical-Chemical Medicine of Federal Medical Biological Agency, Moscow, Russian Federation
| | - Maryam B Khadzhieva
- Dmitry Rogachev National Research Center of Pediatric Hematology, Oncology and Immunology, Moscow, Russian Federation.,Federal Research and Clinical Center of Intensive Care Medicine and Rehabilitology, Moscow, Russian Federation
| | - Elena S Zakharova
- Dmitry Rogachev National Research Center of Pediatric Hematology, Oncology and Immunology, Moscow, Russian Federation
| | - Veronika D Gordeeva
- Federal Research and Clinical Center of Physical-Chemical Medicine of Federal Medical Biological Agency, Moscow, Russian Federation
| | - Nataliya S Smetanina
- Dmitry Rogachev National Research Center of Pediatric Hematology, Oncology and Immunology, Moscow, Russian Federation
| | - Irina V Fedyushkina
- Federal Research and Clinical Center of Physical-Chemical Medicine of Federal Medical Biological Agency, Moscow, Russian Federation
| | - Lyudmila A Anastasevich
- Dmitry Rogachev National Research Center of Pediatric Hematology, Oncology and Immunology, Moscow, Russian Federation
| | - Sergey S Larin
- Dmitry Rogachev National Research Center of Pediatric Hematology, Oncology and Immunology, Moscow, Russian Federation
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Zlomuzica A, Plank L, Dere E. A new path to mental disorders: Through gap junction channels and hemichannels. Neurosci Biobehav Rev 2022; 142:104877. [PMID: 36116574 DOI: 10.1016/j.neubiorev.2022.104877] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2022] [Revised: 08/20/2022] [Accepted: 09/13/2022] [Indexed: 11/18/2022]
Abstract
Behavioral disturbances related to emotional regulation, reward processing, cognition, sleep-wake regulation and activity/movement represent core symptoms of most common mental disorders. Increasing empirical and theoretical evidence suggests that normal functioning of these behavioral domains relies on fine graded coordination of neural and glial networks which are maintained and modulated by intercellular gap junction channels and unapposed pannexin or connexin hemichannels. Dysfunctions in these networks might contribute to the development and maintenance of psychopathological and neurobiological features associated with mental disorders. Here we review and discuss the evidence indicating a prominent role of gap junction channel and hemichannel dysfunction in core symptoms of mental disorders. We further discuss how the increasing knowledge on intercellular gap junction channels and unapposed pannexin or connexin hemichannels in the brain might lead to deeper mechanistic insight in common mental disorders and to the development of novel treatment approaches. We further attempt to exemplify what type of future research on this topic could be integrated into multidimensional approaches to understand and cure mental disorders.
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Affiliation(s)
- Armin Zlomuzica
- Department of Behavioral and Clinical Neuroscience, Ruhr-University Bochum (RUB), Massenbergstraße 9-13, D-44787 Bochum, Germany.
| | - Laurin Plank
- Department of Behavioral and Clinical Neuroscience, Ruhr-University Bochum (RUB), Massenbergstraße 9-13, D-44787 Bochum, Germany
| | - Ekrem Dere
- Department of Behavioral and Clinical Neuroscience, Ruhr-University Bochum (RUB), Massenbergstraße 9-13, D-44787 Bochum, Germany; Sorbonne Université. Institut de Biologie Paris-Seine, (IBPS), Département UMR 8256: Adaptation Biologique et Vieillissement, UFR des Sciences de la Vie, Campus Pierre et Marie Curie, Bâtiment B, 9 quai Saint Bernard, F-75005 Paris, France.
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Viakhireva I, Kalinchenko N, Vasilyev E, Chistousova GV, Filatova A, Marakhonov A, Rubtsov PM, Skoblov M, Tiulpakov A. A Founder Mutation in the POMC 5'-UTR Causes Proopiomelanocortin Deficiency Through Splicing-Mediated Decrease of mRNA. J Clin Endocrinol Metab 2022; 107:e3654-e3660. [PMID: 35775692 DOI: 10.1210/clinem/dgac397] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/30/2022] [Indexed: 11/19/2022]
Abstract
CONTEXT The syndrome of adrenal insufficiency, obesity, and red hair is a rare autosomal recessive disorder. The majority of disease-causing variants associated with the syndrome are located in the coding region of the POMC gene. OBJECTIVE This work describes 7 unrelated patients who shared a novel homozygous mutation in the 5'-untranslated region (UTR) of the POMC gene and functionally characterize this novel variant. METHODS Whole-exome sequencing (WES) with autozygosity mapping, Sanger sequencing, model expression system studies, and RNA sequencing were used for identification of the disease-causing variant and its subsequent functional characterization. Seven unrelated patients of the Perm Tatar ethnic group presented with hypoglycemia and excessive weight gain, low plasma adrenocorticotropin, and cortisol. Five of 7 children had red hair; 6 of 7 patients also showed signs of bronchial obstruction. RESULTS WES showed shared autozygosity regions overlapping the POMC gene. Sanger sequencing of the POMC 5'-UTR detected a homozygous variant chr2:25391366C > T (hg19) at the splice donor site of intron 1. As demonstrated by the model expression system, the variant led to a significant decrease in the POMC messenger RNA level. Analyses of the patients' haplotypes were suggestive of the founder effect. We estimate that the mutation must have occurred at least 4.27 generations ago (95% CI, 0.86-7.67). CONCLUSION This report presents a new molecular mechanism of POMC deficiency and contributes to the information on phenotypic variability in patients with this disorder.
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Affiliation(s)
- Iuliia Viakhireva
- Department of Endocrine Genetics, Research Centre for Medical Genetics, 115522 Moscow, Russian Federation
| | | | - Evgeny Vasilyev
- Endocrinology Research Centre, Moscow 117036, Russian Federation
| | | | - Alexandra Filatova
- Department of Endocrine Genetics, Research Centre for Medical Genetics, 115522 Moscow, Russian Federation
| | - Andrey Marakhonov
- Department of Endocrine Genetics, Research Centre for Medical Genetics, 115522 Moscow, Russian Federation
| | - Petr M Rubtsov
- Engelhardt Institute of Molecular Biology of Russian Academy of Sciences, Moscow 119991, Russian Federation
| | - Mikhail Skoblov
- Department of Endocrine Genetics, Research Centre for Medical Genetics, 115522 Moscow, Russian Federation
| | - Anatoly Tiulpakov
- Department of Endocrine Genetics, Research Centre for Medical Genetics, 115522 Moscow, Russian Federation
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Abstract
Demyelinating forms of Charcot-Marie-Tooth disease (CMT) are genetically and phenotypically heterogeneous and result from highly diverse biological mechanisms including gain of function (including dominant negative effects) and loss of function. While no definitive treatment is currently available, rapid advances in defining the pathomechanisms of demyelinating CMT have led to promising pre-clinical studies, as well as emerging clinical trials. Especially promising are the recently completed pre-clinical genetic therapy studies in PMP-22, GJB1, and SH3TC2-associated neuropathies, particularly given the success of similar approaches in humans with spinal muscular atrophy and transthyretin familial polyneuropathy. This article focuses on neuropathies related to mutations in PMP-22, MPZ, and GJB1, which together comprise the most common forms of demyelinating CMT, as well as on select rarer forms for which promising treatment targets have been identified. Clinical characteristics and pathomechanisms are reviewed in detail, with emphasis on therapeutically targetable biological pathways. Also discussed are the challenges facing the CMT research community in its efforts to advance the rapidly evolving biological insights to effective clinical trials. These considerations include the limitations of currently available animal models, the need for personalized medicine approaches/allele-specific interventions for select forms of demyelinating CMT, and the increasing demand for optimal clinical outcome assessments and objective biomarkers.
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Affiliation(s)
- Vera Fridman
- Department of Neurology, University of Colorado Anschutz Medical Campus, 12631 E 17th Avenue, Mailstop B185, Room 5113C, Aurora, CO, 80045, USA.
| | - Mario A Saporta
- Department of Neurology, University of Miami Miller School of Medicine, Miami, FL, USA
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Nerve Biopsy in Peripheral Neuropathies: Not All Water Is under the Bridge. Brain Sci 2021; 11:brainsci11050550. [PMID: 33925500 PMCID: PMC8145769 DOI: 10.3390/brainsci11050550] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2021] [Accepted: 04/22/2021] [Indexed: 11/24/2022] Open
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