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Bernacchia A, Ginaca A, Rotondo S, Tejada MP, Di Giovanni D. Case Report: C3 deficiency in two siblings. Front Pediatr 2024; 12:1424380. [PMID: 39114852 PMCID: PMC11303290 DOI: 10.3389/fped.2024.1424380] [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: 04/27/2024] [Accepted: 07/10/2024] [Indexed: 08/10/2024] Open
Abstract
The complement system, a vital component of innate immunity, consists of various proteins and pathways crucial for the recognition and elimination of pathogens. In addition, it plays a major role in the initiation of adaptive response through the opsonization of antigens, contributing to B-cell activation and memory maintenance. Deficiencies in complement proteins, particularly C3, can lead to severe and recurrent infections as well as immune complex disorders. Here, we present a case report of two siblings with total C3 deficiency resulting from compound heterozygous mutations in C3 (NM_000064.4): c.305dup; [p.Asn103GlnfsTer66] and c.1269 + 5G>T, previously unreported in C3-related diseases. Both, the index case and her sister, presented a history of recurrent infections since early childhood and one of them developed hemolytic uremic syndrome (HUS). Immunological evaluation revealed absent plasma C3 levels, decreased memory B cells, hypogammaglobulinemia, and impaired response to polysaccharide antigens. The siblings showed partial responses to antimicrobial prophylaxis and vaccination, requiring intravenous immunoglobulin replacement therapy, resulting in clinical improvement. Genetic analysis identified additional risk polymorphisms associated with atypical HUS. This case highlights the importance of comprehensive genetic and immunological evaluations in complement deficiencies, along with the potential role of immunoglobulin replacement therapy in managing associated antibody defects.
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Affiliation(s)
- Agustín Bernacchia
- Servicio de Inmunología, Hospital de Niños Ricardo Gutierrez, Buenos Aires, Argentina
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Balduit A, Bianco AM, Mangogna A, Zicari AM, Leonardi L, Cinicola BL, Capponi M, Tommasini A, Agostinis C, d’Adamo AP, Bulla R. Genetic bases of C7 deficiency: systematic review and report of a novel deletion determining functional hemizygosity. Front Immunol 2023; 14:1192690. [PMID: 37304269 PMCID: PMC10248053 DOI: 10.3389/fimmu.2023.1192690] [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: 03/23/2023] [Accepted: 05/15/2023] [Indexed: 06/13/2023] Open
Abstract
Primary complement system (C) deficiencies are rare but notably associated with an increased risk of infections, autoimmunity, or immune disorders. Patients with terminal pathway C-deficiency have a 1,000- to 10,000-fold-higher risk of Neisseria meningitidis infections and should be therefore promptly identified to minimize the likelihood of further infections and to favor vaccination. In this paper, we performed a systematic review about clinical and genetic patterns of C7 deficiency starting from the case of a ten-year old boy infected by Neisseria meningitidis B and with clinical presentation suggestive of reduced C activity. Functional assay via Wieslab ELISA Kit confirmed a reduction in total C activity of the classical (0.6% activity), lectin (0.2% activity) and alternative (0.1% activity) pathways. Western blot analysis revealed the absence of C7 in patient serum. Sanger sequencing of genomic DNA extracted from peripheral blood of the patient allowed the identification of two pathogenetic variants in the C7 gene: the already well-characterized missense mutation G379R and a novel heterozygous deletion of three nucleotides located at the 3'UTR (c.*99_*101delTCT). This mutation resulted in an instability of the mRNA; thus, only the allele containing the missense mutation was expressed, making the proband a functional hemizygote for the expression of the mutated C7 allele.
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Affiliation(s)
- Andrea Balduit
- Institute for Maternal and Child Health - IRCCS “Burlo Garofolo”, Trieste, Italy
| | - Anna Monica Bianco
- Institute for Maternal and Child Health - IRCCS “Burlo Garofolo”, Trieste, Italy
| | - Alessandro Mangogna
- Institute for Maternal and Child Health - IRCCS “Burlo Garofolo”, Trieste, Italy
| | - Anna Maria Zicari
- Department of Maternal and Child Health and Urological Sciences, Sapienza University of Rome, Rome, Italy
| | - Lucia Leonardi
- Department of Maternal and Child Health and Urological Sciences, Sapienza University of Rome, Rome, Italy
| | - Bianca Laura Cinicola
- Department of Maternal and Child Health and Urological Sciences, Sapienza University of Rome, Rome, Italy
- Department of Molecular Medicine, Sapienza University of Rome, Rome, Italy
| | - Martina Capponi
- Department of Maternal and Child Health and Urological Sciences, Sapienza University of Rome, Rome, Italy
| | - Alberto Tommasini
- Institute for Maternal and Child Health - IRCCS “Burlo Garofolo”, Trieste, Italy
- Department of Medical, Surgical and Health Science, University of Trieste, Trieste, Italy
| | - Chiara Agostinis
- Institute for Maternal and Child Health - IRCCS “Burlo Garofolo”, Trieste, Italy
| | - Adamo Pio d’Adamo
- Institute for Maternal and Child Health - IRCCS “Burlo Garofolo”, Trieste, Italy
- Department of Medical, Surgical and Health Science, University of Trieste, Trieste, Italy
| | - Roberta Bulla
- Department of Life Sciences, University of Trieste, Trieste, Italy
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Sullivan KE. The yin and the yang of early classical pathway complement disorders. Clin Exp Immunol 2022; 209:151-160. [PMID: 35648651 PMCID: PMC9390844 DOI: 10.1093/cei/uxac056] [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: 03/30/2022] [Revised: 05/13/2022] [Accepted: 05/31/2022] [Indexed: 11/12/2022] Open
Abstract
The classical pathway of the complement cascade has been recognized as a key activation arm, partnering with the lectin activation arm and the alternative pathway to cleave C3 and initiate the assembly of the terminal components. While deficiencies of classical pathway components have been recognized since 1966, only recently have gain-of-function variants been described for some of these proteins. Loss-of-function variants in C1, C4, and C2 are most often associated with lupus and systemic infections with encapsulated bacteria. C3 deficiency varies slightly from this phenotypic class with membranoproliferative glomerulonephritis and infection as the dominant phenotypes. The gain-of-function variants recently described for C1r and C1s lead to periodontal Ehlers Danlos syndrome, a surprisingly structural phenotype. Gain-of-function in C3 and C2 are associated with endothelial manifestations including hemolytic uremic syndrome and vasculitis with C2 gain-of-function variants thus far having been reported in patients with a C3 glomerulopathy. This review will discuss the loss-of-function and gain-of-function phenotypes and place them within the larger context of complement deficiencies.
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Affiliation(s)
- Kathleen E Sullivan
- Division of Allergy Immunology, The Children’s Hospital of Philadelphia, 3615 Civic Center Blvd., Philadelphia, PA 19104, USA
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Brodszki N, Frazer-Abel A, Grumach AS, Kirschfink M, Litzman J, Perez E, Seppänen MRJ, Sullivan KE, Jolles S. European Society for Immunodeficiencies (ESID) and European Reference Network on Rare Primary Immunodeficiency, Autoinflammatory and Autoimmune Diseases (ERN RITA) Complement Guideline: Deficiencies, Diagnosis, and Management. J Clin Immunol 2020; 40:576-591. [PMID: 32064578 PMCID: PMC7253377 DOI: 10.1007/s10875-020-00754-1] [Citation(s) in RCA: 35] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2019] [Accepted: 01/20/2020] [Indexed: 12/14/2022]
Abstract
This guideline aims to describe the complement system and the functions of the constituent pathways, with particular focus on primary immunodeficiencies (PIDs) and their diagnosis and management. The complement system is a crucial part of the innate immune system, with multiple membrane-bound and soluble components. There are three distinct enzymatic cascade pathways within the complement system, the classical, alternative and lectin pathways, which converge with the cleavage of central C3. Complement deficiencies account for ~5% of PIDs. The clinical consequences of inherited defects in the complement system are protean and include increased susceptibility to infection, autoimmune diseases (e.g., systemic lupus erythematosus), age-related macular degeneration, renal disorders (e.g., atypical hemolytic uremic syndrome) and angioedema. Modern complement analysis allows an in-depth insight into the functional and molecular basis of nearly all complement deficiencies. However, therapeutic options remain relatively limited for the majority of complement deficiencies with the exception of hereditary angioedema and inhibition of an overactivated complement system in regulation defects. Current management strategies for complement disorders associated with infection include education, family testing, vaccinations, antibiotics and emergency planning.
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Affiliation(s)
- Nicholas Brodszki
- Department of Pediatrics, Children's Hospital, Skåne University Hospital, Lund, Sweden
| | - Ashley Frazer-Abel
- Division of Rheumatology, Department of Medicine, University of Colorado School of Medicine, Aurora, CO, USA
| | - Anete S Grumach
- Clinical Immunology, Reference Center on Rare Diseases, University Center Health ABC, Santo Andre, SP, Brazil
| | | | - Jiri Litzman
- Department of Clinical Immunology and Allergology, St Anne's University Hospital, and Faculty of Medicine, Masaryk University, Brno, Czech Republic
| | - Elena Perez
- Allergy Associates of the Palm Beaches, North Palm Beach, FL, USA
| | - Mikko R J Seppänen
- Rare Disease Center, Children's Hospital, and Adult Primary Immunodeficiency Outpatient Clinic, Inflammation Center, University of Helsinki and Helsinki University Hospital, Helsinki, Finland
| | - Kathleen E Sullivan
- Division of Allergy and Immunology, The Children's Hospital of Philadelphia, Philadelphia, PA, USA
| | - Stephen Jolles
- Immunodeficiency Centre for Wales, Cardiff University & University Hospital of Wales, Cardiff, UK.
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Schröder-Braunstein J, Kirschfink M. Complement deficiencies and dysregulation: Pathophysiological consequences, modern analysis, and clinical management. Mol Immunol 2019; 114:299-311. [PMID: 31421540 DOI: 10.1016/j.molimm.2019.08.002] [Citation(s) in RCA: 40] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2019] [Revised: 07/31/2019] [Accepted: 08/03/2019] [Indexed: 02/07/2023]
Abstract
Complement defects are associated with an enhanced risk of a broad spectrum of infectious as well as systemic or local inflammatory and thrombotic disorders. Inherited complement deficiencies have been described for virtually all complement components but can be mimicked by autoantibodies, interfering with the activity of specific complement components, convertases or regulators. While being rare, diseases related to complement deficiencies are often severe with a frequent but not exclusive manifestation during childhood. Whereas defects of early components of the classical pathway significantly increase the risk of autoimmune disorders, lack of components of the terminal pathway as well as of properdin are associated with an enhanced susceptibility to meningococcal infections. The impaired synthesis or function of C1 inhibitor results in the development of hereditary angioedema (HAE). Furthermore, complement dysregulation causes renal disorders such as atypical hemolytic uremic syndrome (aHUS) or C3 glomerulopathy (C3G) but also age-related macular degeneration (AMD). While paroxysmal nocturnal hemoglobinuria (PNH) results from the combined deficiency of the regulatory complement proteins CD55 and CD59, which is caused by somatic mutation of a common membrane anchor, isolated CD55 or CD59 deficiency is associated with the CHAPLE syndrome and polyneuropathy, respectively. Here, we provide an overview on clinical disorders related to complement deficiencies or dysregulation and describe diagnostic strategies required for their comprehensive molecular characterization - a prerequisite for informed decisions on the therapeutic management of these disorders.
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Affiliation(s)
- Jutta Schröder-Braunstein
- University of Heidelberg, Institute of Immunology, Im Neuenheimer Feld 305, 69120 Heidelberg, Germany
| | - Michael Kirschfink
- University of Heidelberg, Institute of Immunology, Im Neuenheimer Feld 305, 69120 Heidelberg, Germany.
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