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Posukh OL, Maslova EA, Danilchenko VY, Zytsar MV, Orishchenko KE. Functional Consequences of Pathogenic Variants of the GJB2 Gene (Cx26) Localized in Different Cx26 Domains. Biomolecules 2023; 13:1521. [PMID: 37892203 PMCID: PMC10604905 DOI: 10.3390/biom13101521] [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: 09/15/2023] [Revised: 10/08/2023] [Accepted: 10/10/2023] [Indexed: 10/29/2023] Open
Abstract
One of the most common forms of genetic deafness has been predominantly associated with pathogenic variants in the GJB2 gene, encoding transmembrane protein connexin 26 (Cx26). The Cx26 molecule consists of an N-terminal domain (NT), four transmembrane domains (TM1-TM4), two extracellular loops (EL1 and EL2), a cytoplasmic loop, and a C-terminus (CT). Pathogenic variants in the GJB2 gene, resulting in amino acid substitutions scattered across the Cx26 domains, lead to a variety of clinical outcomes, including the most common non-syndromic autosomal recessive deafness (DFNB1A), autosomal dominant deafness (DFNA3A), as well as syndromic forms combining hearing loss and skin disorders. However, for rare and poorly documented variants, information on the mode of inheritance is often lacking. Numerous in vitro studies have been conducted to elucidate the functional consequences of pathogenic GJB2 variants leading to amino acid substitutions in different domains of Cx26 protein. In this work, we summarized all available data on a mode of inheritance of pathogenic GJB2 variants leading to amino acid substitutions and reviewed published information on their functional effects, with an emphasis on their localization in certain Cx26 domains.
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Affiliation(s)
- Olga L. Posukh
- Federal Research Center Institute of Cytology and Genetics, Siberian Branch of the Russian Academy of Sciences, 630090 Novosibirsk, Russia; (E.A.M.); (V.Y.D.); (M.V.Z.); (K.E.O.)
- Novosibirsk State University, 630090 Novosibirsk, Russia
| | - Ekaterina A. Maslova
- Federal Research Center Institute of Cytology and Genetics, Siberian Branch of the Russian Academy of Sciences, 630090 Novosibirsk, Russia; (E.A.M.); (V.Y.D.); (M.V.Z.); (K.E.O.)
- Novosibirsk State University, 630090 Novosibirsk, Russia
| | - Valeriia Yu. Danilchenko
- Federal Research Center Institute of Cytology and Genetics, Siberian Branch of the Russian Academy of Sciences, 630090 Novosibirsk, Russia; (E.A.M.); (V.Y.D.); (M.V.Z.); (K.E.O.)
- Novosibirsk State University, 630090 Novosibirsk, Russia
| | - Marina V. Zytsar
- Federal Research Center Institute of Cytology and Genetics, Siberian Branch of the Russian Academy of Sciences, 630090 Novosibirsk, Russia; (E.A.M.); (V.Y.D.); (M.V.Z.); (K.E.O.)
| | - Konstantin E. Orishchenko
- Federal Research Center Institute of Cytology and Genetics, Siberian Branch of the Russian Academy of Sciences, 630090 Novosibirsk, Russia; (E.A.M.); (V.Y.D.); (M.V.Z.); (K.E.O.)
- Novosibirsk State University, 630090 Novosibirsk, Russia
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Of Mycelium and Men: Inherent Human Susceptibility to Fungal Diseases. Pathogens 2023; 12:pathogens12030456. [PMID: 36986378 PMCID: PMC10058615 DOI: 10.3390/pathogens12030456] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2023] [Revised: 03/09/2023] [Accepted: 03/09/2023] [Indexed: 03/17/2023] Open
Abstract
In medical mycology, the main context of disease is iatrogenic-based disease. However, historically, and occasionally, even today, fungal diseases affect humans with no obvious risk factors, sometimes in a spectacular fashion. The field of “inborn errors of immunity” (IEI) has deduced at least some of these previously enigmatic cases; accordingly, the discovery of single-gene disorders with penetrant clinical effects and their immunologic dissection have provided a framework with which to understand some of the key pathways mediating human susceptibility to mycoses. By extension, they have also enabled the identification of naturally occurring auto-antibodies to cytokines that phenocopy such susceptibility. This review provides a comprehensive update of IEI and autoantibodies that inherently predispose humans to various fungal diseases.
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Alsabbagh MM. Keratitis-ichthyosis-deafness syndrome: A comprehensive review of cutaneous and systemic manifestations. Pediatr Dermatol 2023; 40:19-27. [PMID: 36444857 DOI: 10.1111/pde.15201] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/13/2022] [Accepted: 11/05/2022] [Indexed: 11/30/2022]
Abstract
Keratitis-ichthyosis-deafness syndrome is a rare genetic disease presenting with cutaneous, ocular, and otic defects. This comprehensive review provides insight into the clinical presentations, highlighting the cutaneous manifestations including histopathology and treatment options.
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Affiliation(s)
- Manahel Mahmood Alsabbagh
- Department of Molecular Medicine, Princess Al-Jawhara Center for Molecular Medicine and Inherited Disorders, Arabian Gulf University, Manama, Kingdom of Bahrain
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Lilly E, Bunick CG, Maley AM, Zhang S, Spraker MK, Theos AJ, Vivar KL, Seminario-Vidal L, Bennett AE, Sidbury R, Ogawa Y, Akiyama M, Binder B, Hadj-Rabia S, Morotti RA, Glusac EJ, Choate KA, Richard G, Milstone LM. More than keratitis, ichthyosis, and deafness: Multisystem effects of lethal GJB2 mutations. J Am Acad Dermatol 2018; 80:617-625. [PMID: 30287322 DOI: 10.1016/j.jaad.2018.09.042] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2018] [Revised: 09/06/2018] [Accepted: 09/24/2018] [Indexed: 10/28/2022]
Abstract
BACKGROUND Infant death in keratitis-ichthyosis-deafness (KID) syndrome is recognized; its association with specific genotypes and pathophysiology is inadequately understood. OBJECTIVE We sought to discover characteristics that account for poor outcomes in lethal KID syndrome. METHODS We collected 4 new cases and 9 previously reported, genotyped cases of lethal KID syndrome. We performed new molecular modeling of the lethal mutants GJB2 p.A88V and GJB2 p.G45E. RESULTS Infant death occurred in all patients with GJB2 p.G45E and p.A88V; it is unusual with other GJB2 mutations. Early death with those 2 "lethal" mutations is likely multifactorial: during life all had ≥1 serious infection; most had poor weight gain and severe respiratory difficulties; many had additional anatomic abnormalities. Structural modeling of GJB2 p.G45E identified no impact on the salt bridge previously predicted to account for abnormal central carbon dioxide sensing of GJB2 p.A88V. LIMITATIONS This clinical review was retrospective. CONCLUSION GJB2 p.G45E and p.A88V are the only KID syndrome mutations associated with uniform early lethality. Those electrophysiologically severe mutations in GJB2 reveal abnormalities in many organs in lethal KID syndrome. All patients with KID syndrome may have subtle abnormalities beyond the eyes, ears, and skin. Early genotyping of KID syndrome births will inform prognostic discussion.
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Affiliation(s)
- Evelyn Lilly
- Department of Dermatology at Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts.
| | | | - Alexander M Maley
- Department of Dermatology, Emory University School of Medicine, Atlanta, Georgia
| | - Shali Zhang
- Department of Dermatology, Emory University School of Medicine, Atlanta, Georgia
| | - Mary K Spraker
- Department of Dermatology, Emory University School of Medicine, Atlanta, Georgia
| | - Amy J Theos
- Department of Dermatology, University of Alabama at Birmingham, Birmingham, Alabama
| | - Karina L Vivar
- Department of Dermatology and Cutaneous Surgery, University of South Florida, Tampa, Florida
| | - Lucia Seminario-Vidal
- Department of Dermatology and Cutaneous Surgery, University of South Florida, Tampa, Florida
| | - Adam E Bennett
- Department of Dermatology and Cutaneous Surgery, University of South Florida, Tampa, Florida
| | - Robert Sidbury
- Division of Dermatology, Department of Pediatrics, University of Washington School of Medicine, Seattle, Washington
| | - Yasushi Ogawa
- Department of Dermatology, Nagoya University Graduate School of Medicine, Nagoya, Japan
| | - Masashi Akiyama
- Department of Dermatology, Nagoya University Graduate School of Medicine, Nagoya, Japan
| | - Barbara Binder
- Department of Dermatology, Medical University of Graz, Graz, Austria
| | - Smail Hadj-Rabia
- Department of Dermatology, Reference Center for Genodermatoses and Rare Skin Diseases, INSERM U1163, Paris Descartes - Sorbonne Paris Cité University, Imagine Institute, Necker-Enfants Malades Universitary Hospital, Paris, France
| | | | - Earl J Glusac
- Department of Dermatology, Yale School of Medicine, New Haven, Connecticut; Department of Pathology, Yale School of Medicine, New Haven, Connecticut
| | - Keith A Choate
- Department of Dermatology, Yale School of Medicine, New Haven, Connecticut; Department of Pathology, Yale School of Medicine, New Haven, Connecticut
| | | | - Leonard M Milstone
- Department of Dermatology, Yale School of Medicine, New Haven, Connecticut
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Connexin channels in congenital skin disorders. Semin Cell Dev Biol 2016; 50:4-12. [PMID: 26775130 DOI: 10.1016/j.semcdb.2015.11.018] [Citation(s) in RCA: 57] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2015] [Accepted: 11/23/2015] [Indexed: 11/22/2022]
Abstract
Gap junctions and hemichannels comprised of connexins influence epidermal proliferation and differentiation. Significant advances in our understanding of the functional role of connexins in the skin have been made by studying the diseases caused by connexin mutations. Eleven clinically defined cutaneous disorders with an overlapping spectrum of phenotypes are caused by mutations in five different connexin genes, highlighting that disease presentation must be deciphered with an understanding of how connexin functions are affected. Increasing evidence suggests that the skin diseases produced by connexin mutations result from dominant gains of function. In palmoplantar keratoderma with deafness, the connexin 26 mutations transdominantly alter the function of wild-type connexin 43 and create leaky heteromeric hemichannels. In keratitis-ichthyosis-deafness syndrome, different connexin 26 mutations can either form dominant hemichannels with altered calcium regulation or increased calcium permeability, leading to clinical subtypes of this syndrome. It is only with detailed understanding of these subtle functional differences that we can hope to create successful pathophysiology driven therapies for the connexin skin disorders.
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