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von Hardenberg S, Klefenz I, Steinemann D, Di Donato N, Baumann U, Auber B, Klemann C. Current genetic diagnostics in inborn errors of immunity. Front Pediatr 2024; 12:1279112. [PMID: 38659694 PMCID: PMC11039790 DOI: 10.3389/fped.2024.1279112] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/17/2023] [Accepted: 03/28/2024] [Indexed: 04/26/2024] Open
Abstract
New technologies in genetic diagnostics have revolutionized the understanding and management of rare diseases. This review highlights the significant advances and latest developments in genetic diagnostics in inborn errors of immunity (IEI), which encompass a diverse group of disorders characterized by defects in the immune system, leading to increased susceptibility to infections, autoimmunity, autoinflammatory diseases, allergies, and malignancies. Various diagnostic approaches, including targeted gene sequencing panels, whole exome sequencing, whole genome sequencing, RNA sequencing, or proteomics, have enabled the identification of causative genetic variants of rare diseases. These technologies not only facilitated the accurate diagnosis of IEI but also provided valuable insights into the underlying molecular mechanisms. Emerging technologies, currently mainly used in research, such as optical genome mapping, single cell sequencing or the application of artificial intelligence will allow even more insights in the aetiology of hereditary immune defects in the near future. The integration of genetic diagnostics into clinical practice significantly impacts patient care. Genetic testing enables early diagnosis, facilitating timely interventions and personalized treatment strategies. Additionally, establishing a genetic diagnosis is necessary for genetic counselling and prognostic assessments. Identifying specific genetic variants associated with inborn errors of immunity also paved the way for the development of targeted therapies and novel therapeutic approaches. This review emphasizes the challenges related with genetic diagnosis of rare diseases and provides future directions, specifically focusing on IEI. Despite the tremendous progress achieved over the last years, several obstacles remain or have become even more important due to the increasing amount of genetic data produced for each patient. This includes, first and foremost, the interpretation of variants of unknown significance (VUS) in known IEI genes and of variants in genes of unknown significance (GUS). Although genetic diagnostics have significantly contributed to the understanding and management of IEI and other rare diseases, further research, exchange between experts from different clinical disciplines, data integration and the establishment of comprehensive guidelines are crucial to tackle the remaining challenges and maximize the potential of genetic diagnostics in the field of rare diseases, such as IEI.
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Affiliation(s)
| | - Isabel Klefenz
- Department of Human Genetics, Hannover Medical School, Hannover, Germany
| | - Doris Steinemann
- Department of Human Genetics, Hannover Medical School, Hannover, Germany
| | - Nataliya Di Donato
- Department of Human Genetics, Hannover Medical School, Hannover, Germany
| | - Ulrich Baumann
- Department of Pediatric Pneumology, Allergology and Neonatology, Hannover Medical School, Hannover, Germany
| | - Bernd Auber
- Department of Human Genetics, Hannover Medical School, Hannover, Germany
| | - Christian Klemann
- Department of Human Genetics, Hannover Medical School, Hannover, Germany
- Department of Pediatric Immunology, Rheumatology and Infectiology, Hospital for Children and Adolescents, University of Leipzig, Leipzig, Germany
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Della Mina E, Jackson KJL, Crawford AJI, Faulks ML, Pathmanandavel K, Acquarola N, O'Sullivan M, Kerre T, Naesens L, Claes K, Goodnow CC, Haerynck F, Kracker S, Meyts I, D'Orsogna LJ, Ma CS, Tangye SG. A Novel Heterozygous Variant in AICDA Impairs Ig Class Switching and Somatic Hypermutation in Human B Cells and is Associated with Autosomal Dominant HIGM2 Syndrome. J Clin Immunol 2024; 44:66. [PMID: 38363477 PMCID: PMC10873450 DOI: 10.1007/s10875-024-01665-1] [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: 09/24/2023] [Accepted: 01/21/2024] [Indexed: 02/17/2024]
Abstract
B cells and their secreted antibodies are fundamental for host-defense against pathogens. The generation of high-affinity class switched antibodies results from both somatic hypermutation (SHM) of the immunoglobulin (Ig) variable region genes of the B-cell receptor and class switch recombination (CSR) which alters the Ig heavy chain constant region. Both of these processes are initiated by the enzyme activation-induced cytidine deaminase (AID), encoded by AICDA. Deleterious variants in AICDA are causal of hyper-IgM syndrome type 2 (HIGM2), a B-cell intrinsic primary immunodeficiency characterised by recurrent infections and low serum IgG and IgA levels. Biallelic variants affecting exons 2, 3 or 4 of AICDA have been identified that impair both CSR and SHM in patients with autosomal recessive HIGM2. Interestingly, B cells from patients with autosomal dominant HIGM2, caused by heterozygous variants (V186X, R190X) located in AICDA exon 5 encoding the nuclear export signal (NES) domain, show abolished CSR but variable SHM. We herein report the immunological and functional phenotype of two related patients presenting with common variable immunodeficiency who were found to have a novel heterozygous variant in AICDA (L189X). This variant led to a truncated AID protein lacking the last 10 amino acids of the NES at the C-terminal domain. Interestingly, patients' B cells carrying the L189X variant exhibited not only greatly impaired CSR but also SHM in vivo, as well as CSR and production of IgG and IgA in vitro. Our findings demonstrate that the NES domain of AID can be essential for SHM, as well as for CSR, thereby refining the correlation between AICDA genotype and SHM phenotype as well as broadening our understanding of the pathophysiology of HIGM disorders.
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Affiliation(s)
- Erika Della Mina
- Garvan Institute of Medical Research, 384 Victoria St, Darlinghurst, NSW, 2010, Australia
- School of Clinical Medicine, Faculty of Medicine and Health, UNSW Sydney, Sydney, Australia
| | - Katherine J L Jackson
- Garvan Institute of Medical Research, 384 Victoria St, Darlinghurst, NSW, 2010, Australia
| | - Alexander J I Crawford
- Garvan Institute of Medical Research, 384 Victoria St, Darlinghurst, NSW, 2010, Australia
| | - Megan L Faulks
- Garvan Institute of Medical Research, 384 Victoria St, Darlinghurst, NSW, 2010, Australia
| | - Karrnan Pathmanandavel
- Garvan Institute of Medical Research, 384 Victoria St, Darlinghurst, NSW, 2010, Australia
- School of Clinical Medicine, Faculty of Medicine and Health, UNSW Sydney, Sydney, Australia
| | - Nicolino Acquarola
- Department of Clinical Immunology and PathWest, Fiona Stanley Hospital, Murdoch, WA, Australia
| | - Michael O'Sullivan
- Department of Clinical Immunology and PathWest, Fiona Stanley Hospital, Murdoch, WA, Australia
- Department of Immunology, Perth Children's Hospital, Perth, WA, Australia
| | - Tessa Kerre
- Department of Hematology, Department of Internal Medicine and Pediatrics, Ghent University, Ghent, Belgium
- Center for Primary Immunodeficiency Ghent (CPIG), Jeffrey Modell Diagnosis and Research Center, ERN Rita Network Center, Ghent University Hospital, Ghent, Belgium
| | - Leslie Naesens
- Center for Primary Immunodeficiency Ghent (CPIG), Jeffrey Modell Diagnosis and Research Center, ERN Rita Network Center, Ghent University Hospital, Ghent, Belgium
- Primary Immunodeficiency Research Lab, Department of Internal Medicine and Pediatrics, Ghent University, Ghent, Belgium
| | - Karlien Claes
- Center for Primary Immunodeficiency Ghent (CPIG), Jeffrey Modell Diagnosis and Research Center, ERN Rita Network Center, Ghent University Hospital, Ghent, Belgium
- Primary Immunodeficiency Research Lab, Department of Internal Medicine and Pediatrics, Ghent University, Ghent, Belgium
| | - Christopher C Goodnow
- Garvan Institute of Medical Research, 384 Victoria St, Darlinghurst, NSW, 2010, Australia
- School of Clinical Medicine, Faculty of Medicine and Health, UNSW Sydney, Sydney, Australia
| | - Filomeen Haerynck
- Center for Primary Immunodeficiency Ghent (CPIG), Jeffrey Modell Diagnosis and Research Center, ERN Rita Network Center, Ghent University Hospital, Ghent, Belgium
- Primary Immunodeficiency Research Lab, Department of Internal Medicine and Pediatrics, Ghent University, Ghent, Belgium
| | - Sven Kracker
- Laboratory of Human Lymphohematopoiesis, INSERM UMR 1163, Imagine Institute, 75015, Paris, France
- Université Paris Cité, 75015, Paris, France
| | - Isabelle Meyts
- Inborn Errors of Immunity, Department of Microbiology, Immunology and Transplantation, KU Leuven, Louvain, Belgium
- Pediatric Immunodeficiency, Department of Pediatrics, University Hospitals Leuven, Louvain, Belgium
| | - Lloyd J D'Orsogna
- Department of Clinical Immunology and PathWest, Fiona Stanley Hospital, Murdoch, WA, Australia
- School of Medicine, University of Western Australia, Nedlands, WA, Australia
| | - Cindy S Ma
- Garvan Institute of Medical Research, 384 Victoria St, Darlinghurst, NSW, 2010, Australia
- School of Clinical Medicine, Faculty of Medicine and Health, UNSW Sydney, Sydney, Australia
| | - Stuart G Tangye
- Garvan Institute of Medical Research, 384 Victoria St, Darlinghurst, NSW, 2010, Australia.
- School of Clinical Medicine, Faculty of Medicine and Health, UNSW Sydney, Sydney, Australia.
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Denis-Lagache N, Oblet C, Marchiol T, Baylet A, Têteau O, Dalloul I, Dalloul Z, Zawil L, Dézé O, Cook-Moreau J, Saintamand A, Boutouil H, Khamlichi AA, Carrion C, Péron S, Le Noir S, Laffleur B, Cogné M. Attempts to evaluate locus suicide recombination and its potential role in B cell negative selection in the mouse. Front Immunol 2023; 14:1155906. [PMID: 37359540 PMCID: PMC10288998 DOI: 10.3389/fimmu.2023.1155906] [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: 01/31/2023] [Accepted: 05/09/2023] [Indexed: 06/28/2023] Open
Abstract
Introduction In mature B cells, activation-induced deaminase reshapes Ig genes through somatic hypermutation and class switch recombination of the Ig heavy chain (IgH) locus under control of its 3' cis-regulatory region (3'RR). The 3'RR is itself transcribed and can undergo "locus suicide recombination" (LSR), then deleting the constant gene cluster and terminating IgH expression. The relative contribution of LSR to B cell negative selection remains to be determined. Methods Here, we set up a knock-in mouse reporter model for LSR events with the aim to get clearer insights into the circumstances triggering LSR. In order to explore the consequences of LSR defects, we reciprocally explored the presence of autoantibodies in various mutant mouse lines in which LSR was perturbed by the lack of Sµ or of the 3'RR. Results Evaluation of LSR events in a dedicated reporter mouse model showed their occurrence in various conditions of B cell activation, notably in antigen-experienced B cells Studies of mice with LSR defects evidenced increased amounts of self-reactive antibodies. Discussion While the activation pathways associated with LSR are diverse, in vivo as well as in vitro, this study suggests that LSR may contribute to the elimination of self-reactive B cells.
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Affiliation(s)
- Nicolas Denis-Lagache
- Limoges University, Centre National de la Recherche Scientifique (CNRS), Limoges, France
| | - Christelle Oblet
- Limoges University, Centre National de la Recherche Scientifique (CNRS), Limoges, France
| | - Tiffany Marchiol
- Limoges University, Centre National de la Recherche Scientifique (CNRS), Limoges, France
| | - Audrey Baylet
- Limoges University, Centre National de la Recherche Scientifique (CNRS), Limoges, France
| | - Ophélie Têteau
- Limoges University, Centre National de la Recherche Scientifique (CNRS), Limoges, France
| | - Iman Dalloul
- Limoges University, Centre National de la Recherche Scientifique (CNRS), Limoges, France
| | - Zeinab Dalloul
- Limoges University, Centre National de la Recherche Scientifique (CNRS), Limoges, France
| | - Lina Zawil
- Limoges University, Centre National de la Recherche Scientifique (CNRS), Limoges, France
| | | | - Jeanne Cook-Moreau
- Limoges University, Centre National de la Recherche Scientifique (CNRS), Limoges, France
| | - Alexis Saintamand
- Limoges University, Centre National de la Recherche Scientifique (CNRS), Limoges, France
| | - Hend Boutouil
- Limoges University, Centre National de la Recherche Scientifique (CNRS), Limoges, France
| | - Ahmed Amine Khamlichi
- Institut de Pharmacologie et de Biologie Structurale, Centre National de la Recherche Scientifique (CNRS), Toulouse University, Toulouse, France
| | - Claire Carrion
- Limoges University, Centre National de la Recherche Scientifique (CNRS), Limoges, France
| | - Sophie Péron
- Limoges University, Centre National de la Recherche Scientifique (CNRS), Limoges, France
| | - Sandrine Le Noir
- Limoges University, Centre National de la Recherche Scientifique (CNRS), Limoges, France
| | | | - Michel Cogné
- Limoges University, Centre National de la Recherche Scientifique (CNRS), Limoges, France
- Rennes University, Inserm, Rennes, France
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Prakash PR, Gupta G, Aggarwal M, Baitha U. Type 2 hyper-IgM syndrome with a rare variant of AICDA gene mutation in a young woman. BMJ Case Rep 2023; 16:e253878. [PMID: 36931691 PMCID: PMC10030550 DOI: 10.1136/bcr-2022-253878] [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] [Indexed: 03/19/2023] Open
Abstract
We report the case of a woman in her early 20s with a history of recurrent infection, atopic dermatitis, filariasis and bilateral purulent ear discharge since childhood with tonsillar enlargement on examination. She was started on supportive care and evaluated for primary immunodeficiency disease. Blood investigations revealed increased IgM levels with reduced IgG, IgA and IgE levels. Radiological imaging of the chest revealed bilateral bronchiectasis. Otoscopic examination showed features suggestive of chronic suppurative otitis media. Next-generation sequencing identified homozygous single base pair deletion in exon 2 of the activation-induced cytidine deaminase gene. Thus, a diagnosis of hyper-IgM syndrome type 2 was confirmed. The patient was started on monthly intravenous immunoglobulin replacement therapy and is currently symptomatically better, and she remains under regular follow-up.
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Affiliation(s)
| | - Gaurav Gupta
- Medicine, All India Institute of Medical Sciences, New Delhi, Delhi, India
| | - Mukul Aggarwal
- Hematology, All India Institute of Medical Sciences, New Delhi, Delhi, India
| | - Upendra Baitha
- Medicine, All India Institute of Medical Sciences, New Delhi, Delhi, India
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Della Mina E, Tangye SG. Atypical Autosomal Recessive AID Deficiency-Yet Another Piece of the Hyper-IgM Puzzle. J Clin Immunol 2022; 42:713-715. [PMID: 35332417 DOI: 10.1007/s10875-022-01255-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2022] [Accepted: 03/15/2022] [Indexed: 11/26/2022]
Affiliation(s)
- Erika Della Mina
- Immunology and Immunodeficiency Laboratory, Garvan Institute of Medical Research, 384 Victoria Street, Darlinghurst, New South Wales, 2010, Australia
- St. Vincent's Clinical School, UNSW Sydney, Darlinghurst, New South Wales, 2010, Australia
| | - Stuart G Tangye
- Immunology and Immunodeficiency Laboratory, Garvan Institute of Medical Research, 384 Victoria Street, Darlinghurst, New South Wales, 2010, Australia.
- St. Vincent's Clinical School, UNSW Sydney, Darlinghurst, New South Wales, 2010, Australia.
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