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Massri M, Foco L, Würzner R. Comprehensive Update and Revision of Nomenclature on Complement C6 and C7 Variants. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2022; 208:2597-2612. [PMID: 35867677 DOI: 10.4049/jimmunol.2200045] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/25/2022] [Accepted: 04/11/2022] [Indexed: 06/15/2023]
Abstract
Complement genes encompass a wide array of variants, giving rise to numerous protein isoforms that have often been shown to exhibit clinical significance. Given that these variants have been discovered over a span of 50 y, one challenging consequence is the inconsistency in the terminology used to classify them. This issue is prominently evident in the nomenclature used for complement C6 and C7 variants, for which we observed a great discrepancy between previously published works and variants described in current genome browsers. This report discusses the causes for the discrepancies in C6 and C7 nomenclature and seeks to establish a classification system that would unify existing and future variants. The inconsistency in the methods used to annotate amino acids and the modifications pinpointed in the C6 and C7 primers are some of the factors that contribute greatly to the discrepancy in the nomenclature. Several variants that were classified incorrectly are highlighted in this report, and we showcase first-hand how a unified classification system is important to match previous with current genetic information. Ultimately, we hope that the proposed classification system of nomenclature becomes an incentive for studies on complement variants and their physiological and/or pathological effects.
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Affiliation(s)
- Mariam Massri
- Institute of Hygiene and Medical Microbiology, Medical University of Innsbruck, Innsbruck, Austria; and
| | - Luisa Foco
- Institute for Biomedicine (affiliated with the University of Lübeck), Eurac Research, Bolzano, Italy
| | - Reinhard Würzner
- Institute of Hygiene and Medical Microbiology, Medical University of Innsbruck, Innsbruck, Austria; and
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2
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Barnum SR, Bubeck D, Schein TN. Soluble Membrane Attack Complex: Biochemistry and Immunobiology. Front Immunol 2020; 11:585108. [PMID: 33240274 PMCID: PMC7683570 DOI: 10.3389/fimmu.2020.585108] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2020] [Accepted: 10/14/2020] [Indexed: 12/15/2022] Open
Abstract
The soluble membrane attack complex (sMAC, a.k.a., sC5b-9 or TCC) is generated on activation of complement and contains the complement proteins C5b, C6, C7, C8, C9 together with the regulatory proteins clusterin and/or vitronectin. sMAC is a member of the MACPF/cholesterol-dependent-cytolysin superfamily of pore-forming molecules that insert into lipid bilayers and disrupt cellular integrity and function. sMAC is a unique complement activation macromolecule as it is comprised of several different subunits. To date no complement-mediated function has been identified for sMAC. sMAC is present in blood and other body fluids under homeostatic conditions and there is abundant evidence documenting changes in sMAC levels during infection, autoimmune disease and trauma. Despite decades of scientific interest in sMAC, the mechanisms regulating its formation in healthy individuals and its biological functions in both health and disease remain poorly understood. Here, we review the structural differences between sMAC and its membrane counterpart, MAC, and examine sMAC immunobiology with respect to its presence in body fluids in health and disease. Finally, we discuss the diagnostic potential of sMAC for diagnostic and prognostic applications and potential utility as a companion diagnostic.
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Affiliation(s)
| | - Doryen Bubeck
- Department of Life Sciences, Imperial College London, London, United Kingdom
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Barroso S, Sánchez B, Alvarez AJ, López-Trascasa M, Lanuza A, Luque R, Wichmann I, Núñez-Roldán A. Complement component C7 deficiency in two Spanish families. Immunology 2005; 113:518-23. [PMID: 15554930 PMCID: PMC1782596 DOI: 10.1111/j.1365-2567.2004.01997.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
Different genetic mutations have been described in complement component C7 deficiency, a molecular defect clinically associated with an increased susceptibility to neisserial recurrent infections. In this work we report the genetic basis of C7 deficiency in two different Spanish families (family 1 and family 2). In family 1, of Gypsy ethnical background, exon-specific polymerase chain reaction and sequencing revealed a not previously described single base deletion of nucleotide 1309 (exon 10) in the patient, as well as in her father, leading to a stop codon that causes the premature truncation of the C7 protein (K416 X 419). Additionally, the patient and her mother displayed a missense mutation at position 1135 (exon 9) located in the first nucleotide of the codon GGG (CGG), resulting in a change of amino acid (G357R). This mutation was firstly described in individuals of Moroccan Sephardic Jewish ancestry and has been also reported among Spaniards. In family 2, another novel mutation was found in homozygosity in two siblings; a two base-pair deletion of nucleotides 1922 and 1923 in exon 14 leading to the generation of a downstream stop codon causing the truncation of the C7 protein product (S620 X 630). Our results provide more evidence for the heterogeneous molecular basis of C7 deficiency as well as for the subsequent susceptibility to meningococcal disease, since different families carry different molecular defects. On the other hand, certain C7 defects appear to be prevalent in individuals from certain populations or living in defined geographical areas.
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Affiliation(s)
- Sonia Barroso
- Servicio de Inmunología, Hospital Universitario Virgen del Rocío, Sevilla, Spain
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4
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Corvini M, Randolph C, Aronin SI. Complement C7 deficiency presenting as recurrent aseptic meningitis. Ann Allergy Asthma Immunol 2004; 93:200-5. [PMID: 15328683 DOI: 10.1016/s1081-1206(10)61476-7] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
BACKGROUND Complement deficiency states are rare inherited disorders that may predispose affected individuals to angioedema, collagen vascular disease, or infection due to encapsulated organisms, especially Neisseria meningitidis. OBJECTIVES To report the case of a 36-year-old man of Irish descent with recurrent culture-negative neutrophilic meningitis, to offer potential reasons for the inability to recover a causative pathogen, and to review the genetics and prevalence of complement deficiency states, the methods of screening for such deficiencies, the features of meningococcal infection as they relate to such deficiencies, and management strategies for clinicians caring for patients with such deficiencies. METHODS The patient presented in 1988 and again in 2002 with culture-negative neutrophilic meningitis. His second episode was characterized by a rash suggestive of meningococcal infection, prompting immunologic evaluation. RESULTS Immunologic evaluation revealed an undetectable CH50 level. Levels of C1, C2, and C5 through C9 were normal except for C7, which was undetectable. Further testing revealed that the patient's sister was also C7 deficient. CONCLUSIONS Complement component deficiencies are relatively rare; individuals with collagen vascular disease and systemic neisserial infection should be screened using either the CH50 or the APH-50 assay. Key to the management of a late-complement component-deficient host is counseling, education about meningococcal infection, and discussions about the potential benefits of chemoprophylaxis and immunoprophylaxis. The ability to detect the bacterial cause of meningitis in such patients is organism dependent and may be influenced by factors such as cerebrospinal fluid bacterial concentration and previous antibiotic drug exposure.
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Affiliation(s)
- Michael Corvini
- Waterbury Hospital Health Center, Waterbury, Connecticut 06721, USA
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Vázquez-Bermúdez MF, Barroso S, Walter K, Alvarez AJ, Alarcón A, López-Trascasa M, Wichmann I, Aguilar F, Núñez-Roldán A, Sánchez B. Complement component C7 deficiency in a Spanish family. Clin Exp Immunol 2003; 133:240-6. [PMID: 12869030 PMCID: PMC1808760 DOI: 10.1046/j.1365-2249.2003.02186.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Different genetic mutations have been described in complement component C7 deficiency, a molecular defect which is clinically associated with an increased susceptibility to neisserial recurrent infections, although some cases remain asymptomatic. In this work we report the genetic bases of C7 deficiency in one Spanish family. Exon-specific PCR and sequencing revealed a novel point mutation at nucleotide 615 (exon 6) leading to a stop codon (UGG to UGA) in the patient, his mother, and sister. This transversion causes the premature truncation of the C7 protein (W183X). Additionally, we detected a missense mutation at position 1135 (exon 9) located in the first nucleotide of the codon GGG (CGG), resulting in an amino acid change (G357R) in the patient, his father, as well as in his sister. This latter mutation had been previously described in individuals from Moroccan Sephardic Jewish ancestry. Since both heterozygous mutations were found in the patient as well as in his asymptomatic sister, we analyse other meningococcal defence mechanisms such as polymorphisms of the opsonin receptors on polymorphonuclear cells. Results showed that the patient and his sister bore identical combinations of FcgammaRIIA-H/R131 and FcgammaRIIIB-NA1/2 allotypes. Our results provide further evidence that the molecular pathogenesis of C7 deficiency as well as susceptibility to meningococcal disease are heterogeneous, since different families carry different molecular defects, although many of the C7 defects appear to be homogeneous in individuals from certain geographical areas. The missense mutation G357R would make an interesting topic of analysis with regard to meningococcal disease susceptibility in the Spanish population.
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Affiliation(s)
- M F Vázquez-Bermúdez
- Servicio de Inmunología, Unidad de Infecciosos, Hospital Universitario Virgen del Rocío, Sevilla, Madrid, Spain
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Nishimukai H, Nishimura K, Orimoto C, Okiura T, Fujii K, Fukumori Y, Harihara S. Single nucleotide polymorphisms in the human complement C6 and C7 genes. Leg Med (Tokyo) 2003; 5 Suppl 1:S198-200. [PMID: 12935588 DOI: 10.1016/s1344-6223(02)00110-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
We analyzed the single nucleotide polymorphisms (SNPs) in the sixth (C6) and the seventh (C7) component genes of the complement system in a sample of the Japanese population, using polymerase chain reaction (PCR)-based methods and PCR direct sequencing. SNPs in the C6 gene studied here are as follows: A413C in exon 3, T1674C in exon 10, T7145A in exon 13, G[357+32]A in intron 2, and G[503-78]A in intron 3. We confirmed that nt413A and nt413C were associated with C6A and C6B, respectively. The result of the nt2145 typing showed that two subtypes exist in the C6B allotype. The SNP of G[357+32]A in intron 2 could be analyzed by using the PCR-RFLP method with HinfI. Allele frequencies in the Japanese population were found to be *G=0.920 and *A=0.080. SNPs in the C7 gene are as follows: T382C in exon 4, G1166C and A1258C in exon 9, and G[+10]A in intron 13. Nt382C and nt1258C would be responsible for C7-5 (=C7-3) and C7-4 allotypes, respectively.
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Affiliation(s)
- Hiroaki Nishimukai
- Department of Legal Medicine, Ehime University School of Medicine, Shigenobu-cho, Onsen-gun, Ehime 791-0295, Japan.
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Chataway J, Sawcer S, Sherman D, Hobart M, Fernie B, Coraddu F, Feakes R, Broadley S, Gray J, Jones HB, Clayton D, Goodfellow PN, Compston A. No evidence for association of multiple sclerosis with the complement factors C6 and C7. J Neuroimmunol 1999; 99:150-6. [PMID: 10496188 DOI: 10.1016/s0165-5728(99)00054-5] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Four genome screens in multiple sclerosis have been completed and each has identified evidence for linkage in the pericentromeric region of chromosome 5. This region encodes a number of candidate genes including those for the complement components C6, C7 and C9. We have used a multiplexed oligoligation assay (OLA) to test single nucleotide polymorphisms (SNPs) from the C6 and C7 genes for evidence of association with multiple sclerosis in our sibling pair families. There was no statistically significant difference in the allele frequencies of these polymorphisms in the index cases from our families when compared with locally derived controls. No evidence for transmission distortion was seen with any of the polymorphisms, or with the haplotype built from the three SNPs from the C7 gene. Despite offering themselves as potential candidates these complement genes appear not to confer susceptibility to multiple sclerosis.
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Affiliation(s)
- J Chataway
- University of Cambridge Neurology Unit, Addenbrooke's Hospital, UK
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O'Hara AM, Fernie BA, Moran AP, Williams YE, Connaughton JJ, Orren A, Hobart MJ. C7 deficiency in an Irish family: a deletion defect which is predominant in the Irish. Clin Exp Immunol 1998; 114:355-61. [PMID: 9844043 PMCID: PMC1905122 DOI: 10.1046/j.1365-2249.1998.00737.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Human deficiencies of terminal complement components are known to be associated with increased susceptibility to Neisseria meningitidis infection. Polymorphic DNA marker studies in complement deficient investigations allow identification of haplotypes associated with the deficiency and enable the possible identification of heterozygote carriers of the defect. We report studies of an Irish family in which the index case had suffered recurrent meningococcal disease and was found to be deficient in the seventh component of complement (C7). The availability of all family members enabled us to determine the segregating haplotypes. The defects in the family segregated with two very closely related C6 and C7 DNA haplotypes, one of which is known to be associated with the large Irish C7 DNA deletion defect. The index case and two C7 deficient siblings were found to be homozygous for this defect, a deletion that spans approx. 6.8 kbp and encompasses exons 7 and 8. The deletion defect of exons 7 and 8 of C7 has been found in homozygous form in another C7 deficient Irish individual, and is present in heterozygous form in C7 deficient members of a third Irish family. Therefore, this deletion defect occurs in five of the six deficient chromosomes of these three unrelated Irish families, raising the interesting question of how prevalent this defect may be within the Irish community.
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Affiliation(s)
- A M O'Hara
- Department of Microbiology, National University of Ireland, Galway, Ireland
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Naughton MA, Walport MJ, Würzner R, Carter MJ, Alexander GJ, Goldman JM, Botto M. Organ-specific contribution to circulating C7 levels by the bone marrow and liver in humans. Eur J Immunol 1996; 26:2108-12. [PMID: 8814254 DOI: 10.1002/eji.1830260922] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Many cells types can produce complement component C7, although the major site of C7 synthesis is unknown. Conversion from recipient to donor allotype following organ transplantation has demonstrated the synthetic sites of several complement proteins, but in the case of C7 this was not possible until recently. A novel C7 polymorphism (C7 M/N) has been described based on the reactivity with the monoclonal antibody WU 4-15 which identifies in allotype of C7 (C7 M). Bone marrow and hepatic C7 production was quantified in bone marrow transplant and liver transplant recipients, respectively, where a mismatch for the C7 allotypes distinguished by the monoclonal antibody had occurred. In the bone marrow transplant group, one informative transplant was identified and donor-derived C7 was detected by enzyme-linked immunosorbent assay. It contributed to 18-27% of the total circulating C7 during the post-transplant phase and was increased during episodes of inflammation. In the liver transplant group, the hepatic contribution to the C7 levels were 30% and 52%, respectively, in two patients identified prospectively. A further three informative liver transplant patients were identified retrospectively and in these individuals, 56-62% of the circulating C7 was liver-derived. This study demonstrates that the majority of the circulating C7 is derived from the liver and bone marrow with a lesser contribution from other sources. These findings provide further support for the concept that locally secreted complement proteins have an important role in inflammation.
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Affiliation(s)
- M A Naughton
- Department of Medicine, Royal Postgraduate Medical School, Hammersmith Hospital, London, GB
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Würzner R, Platonov AE, Beloborodov VB, Pereverzev AI, Vershinina IV, Fernie BA, Hobart MJ, Lachmann PJ, Orren A. How partial C7 deficiency with chronic and recurrent bacterial infections can mimic total C7 deficiency: temporary restoration of host C7 levels following plasma transfusion. Immunol Suppl 1996; 88:407-11. [PMID: 8774358 PMCID: PMC1456337 DOI: 10.1046/j.1365-2567.1996.d01-663.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
An apparently completely complement C7-deficient patient with refractory otitis media and two episodes of meningococcal disease was given therapeutic plasma transfusions in 1992 and 1994. Following these transfusions unexpected changes were found in C7 levels. Immediately after transfusion the serum C7 levels failed to rise to the expected levels but then rose to 5-10% of the normal mean during the next 5 days and remained at that level for more than 2 weeks before eventually returning to zero. The patient's DNA genotyped C7 M, and therefore C7 N donor plasma was selected for the second transfusion to allow identification of the source of the C7 circulating post-transfusion. This C7 phenotyped C7 M, demonstrating it to be of recipient origin. Therefore, the apparently completely C7-deficient patient was able to secrete some C7. By a combination of DNA typing and isoelectric focusing of the C7 appearing after transfusion, it was demonstrated that the patient was heterozygous for combined subtotal C6/C7 deficiency (inherited from his father) and a different, so far uncharacterized, subtotal C7 deficiency (inherited from his mother). The low amount of C7 secreted appeared to be constantly consumed, probably by generation of C5b6 as a result of his chronic infection. He had been shown to have circulating C5b6 most of the time, and thus only when sufficient exogenous C7 was given to consume the free C5b6 did his own C7 appear in circulation.
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Affiliation(s)
- R Würzner
- Molecular Immunopathology Unit, Medical Research Council Centre, Cambridge, UK
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Sölder BM, De Stefano GF, Dierich MP, Würzner R. The Cayapa Indians of Ecuador: a genetically isolated group with unexpected complement C7 M/N allele frequencies. EUROPEAN JOURNAL OF IMMUNOGENETICS : OFFICIAL JOURNAL OF THE BRITISH SOCIETY FOR HISTOCOMPATIBILITY AND IMMUNOGENETICS 1996; 23:199-203. [PMID: 8803532 DOI: 10.1111/j.1744-313x.1996.tb00114.x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
The Cayapa Indians live in north-western Ecuador in close proximity to a Black population of African ancestry. C7 M/N allotyping has proved to be a good technique for plasma genetic analysis in several populations. Investigation of 124 Cayapa plasma samples revealed the highest allele frequency of C7*N observed in any population examined so far (0.36 versus 0.225 or lower). The marked difference in frequency compared with several Oriental populations, which are believed to have been derived from the same Asian population as native Amerindians, may reflect the effect of a small founder population followed by a high degree of genetic isolation. The allele frequency of 0.12 for C7*N determined for the neighbouring Black population supports the conclusion that there has been a lack of genetic admixture of Cayapas with other populations, confirming the results of ethnohistorical investigations and other protein polymorphism studies.
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Affiliation(s)
- B M Sölder
- Department of Paediatrics, University of Innsbruck, Austria
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12
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Fernie BA, Würzner R, Orren A, Hobart M. A new intronic polymorphism in the C7 gene 36 bp from the common expressed C7 M/N polymorphism. Ann Hum Genet 1996; 60:179-82. [PMID: 8839131 DOI: 10.1111/j.1469-1809.1996.tb01187.x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
We report a new polymorphism in the complement C7 gene that results from an A-C transversion in intron 12, 27 bp upstream of exon 13 (C712.-27) and 36 bp upstream of the point mutation that underlies the C7 M/N antigenic polymorphism. The C7 12.-27 polymorphism subdivides C7 M haplotypes, but not C7 N. It also sheds light on the evolution of the various types of deficiency genes at the adjacent C6 locus.
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Affiliation(s)
- B A Fernie
- Molecular Immunopathology Unit, MRC Centre, Cambridge, U.K
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