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At least 19 recordsLinked to original sources
PubMed2002

Molecular bases for human complement C7 polymorphisms, C7*3 and C7*4.

Complement C7 is one of the components of membrane attack complex (MAC) generated by the terminal complement cascade. C7 protein is polymorphic and most of its polymorphisms have been identified using isoelectric focusing (IEF), which detects protein charge differences. To date, the molecular bases of the polymorphisms detected by IEF have not been determined. In this paper, we describe the structural bases of two C7 IEF-detected polymorphisms, C7*3 and C7*4, both of which are common in Asian populations. C7*3 resulted from substitution of cysteine (Cys) at amino acid residue 106 by charged arginine (Arg; C106R), while charged lysine (Lys) at amino acid residue 398 was replaced by neutral glutamine (Gln; K398Q) in C7*4. As C7*3 is hypomorphic, it is important to study its possible associations with diseases such as immunological disorders and infections. We present genetic bases for this C7 polymorphism, which we determined using polymerase chain reaction (PCR)-based genotyping, a simple and accurate method suitable for large-scale studies.

Base Sequence↗
PubMed1996

Genetic bases of human complement C7 deficiency.

Complement C7 deficiency (C7D) is associated frequently with recurrent bacterial infections, especially meningitis caused by Neisseria meningitidis. We report in this work the molecular bases of C7D in two unrelated Japanese males. We used exon-specific PCR/single-strand conformation polymorphism analysis as a screening step for mutations. Subsequent direct sequencing of the target exons identified homozygous mutations in exon 16 of case 1 and in exon 15 of case 2. The mutation of case 1 was a homozygous T to A transversion at nucleotide 2250, the third nucleotide of the codon TGT for Cys728, leading to a stop codon TGA (C728X). In case 2, a homozygous 2-bp deletion (2137delTG/2138delGT/2139delTG) caused a frameshift, generating a premature termination codon 4 to 6 nucleotides downstream. Family study in case 1 confirmed the genetic nature of the defect. Moreover, we detected a novel polymorphism in intron 11 that presumably is linked to the mutation responsible for C7D in case 1. Our results indicate that the pathogenesis of C7D is heterogeneous like most of the other deficiencies of complement components.

Adult↗
PubMed2005

Two novel mutations in the C7 gene in a Korean patient with complement C7 deficiency.

Complement C7 deficiency is an autosomal recessive disorder well known to be associated with increased susceptibility to meningococcal infection and has mostly been reported in Caucasians. In the Korean population, no case of C7 deficiency has been reported to date. Recently we experienced an 11-yr-old girl with meningococcal meningitis who was diagnosed as having C7 deficiency based upon the undetectable serum C7 protein on radial immunodiffusion and the undetectable serum total and C7 hemolytic activities. To identify the genetic basis of the C7 deficiency of the patient, we performed a mutation analysis for the C7 gene and found two novel mutations; a point mutation at the 3' splice acceptor site of intron 4 (c.281-1G>T) and a large deletion mutation encompassing almost the whole C7 gene from exon 1 to exon 17 (c.1-?_2350+?del). A haplotype analysis showed that the large deletion mutation was inherited from the patient's father. To the best of our knowledge, this is the first confirmed case of C7 deficiency in Korea.

Child↗
PubMed1991

C7*N is a hypomorphic allele of the human complement c7 M/N protein polymorphism.

Two complement C7 protein polymorphisms exist. One is determined by isoelectric focussing whereas the other is determined by the reaction pattern of a monoclonal C7-allospecific antibody in an ELISA assay. C7 concentrations quantitated by an ELISA based on polyclonal C7-specific IgG and data from functional haemolytic assays were compared with the allotypes of both C7 protein polymorphisms. Testing a randomly selected Japanese population revealed that not only C7*3 but also C7*N is a hypomorphic allele. However, no significant disease association of C7*N or C7*M was found in studies of hospitalized patients.

Asian People↗
PubMed2006

Molecular defects of the C7 gene in two patients with complement C7 deficiency.

Different genetic mutations have been described in complement components resulting in total or subtotal deficiency states. In this work we report the genetic basis of C7 deficiency in a previously reported Spanish patient exhibiting a combined total deficiency of C7 and C4B associated with systemic lupus erythematosus. Exon-specific polymerase chain reaction and sequencing revealed a not previously described single base mutation in exon 10 (T1458A) leading to a stop codon that causes the premature truncation of the C7 protein (C464X). Additionally, a C to A transversion at position 1561 (exon 11) was found in the patient resulting in an amino acid change (R499S). This latter mutation has been previously reported in individuals with subtotal C7 deficiency or with combined subtotal C6/C7 deficiency from widely spaced geographical areas. Another novel mutation was found in a second patient with meningococcal meningitis of Bolivian and Czech origin; a 11-base pair deletion of nucleotides 631-641 in exon 6 leading to the generation of a downstream stop codon causing the premature truncation of the C7 protein product (T189 x 193). This patient was found to be a heterozygous compound for another mutation in C7; a two-base pair deletion of nucleotides 1922 and 1923, 1923 and 1924 or 1924 and 1925 in exon 14 (1922delAG/1923delGA/1924delAG), leading again to the generation of a downstream stop codon that provokes the truncation of the C7 protein (S620x630). This latter mutation has been recently reported by our group in another Spanish family. Our results provide more evidences for the heterogeneous molecular basis of C7 deficiency.

Adult↗
PubMed1991

Selective C7 complement deficiency causing recurrent meningococcal infection.

We report on two sisters both with complete absence of the 7th component of complement. This congenital immunodeficiency disorder is associated with recurrent bacterial infection, especially that due to Neisseria species. These cases illustrate many of the well-recognised features of this disorder, but in one patient the illness was complicated by infective endocarditis due to N. meningitidis, a feature not previously reported.

Adolescent↗
PubMed2006

[Combined-heterozygous deficiency of complement C7 in a patient with recurrent meningitis].

BACKGROUND: The association between complement deficiencies and the increased risk for meningococcal infections and bacterial meningitis is well described and most striking in patients with deficiencies of one of the late complement components, i.e., C5-C9. CASE REPORT: In the presented study the first case of a patient with combined-heterozygous deficiency of complement C7 is described. The defect led to a strongly reduced but still measurable production of C7. However, the low concentration of C7 was not protective against recurrent bacterial meningitis. CONCLUSION: The reported case illustrates once again the necessity of complement analysis in patients with meningitis. Not only patients with undetectable complement activity but also those with strongly reduced but still measurable complement function should be analyzed for a possible complement deficiency.

Adult↗
PubMed1994

A combined study of human complement C7 IEF and C7 M/N polymorphisms in the Chinese Han population.

Two polymorphisms of human complement C7 (IEF and M/N) have been studied in the Han population from Chengdu, People's Republic of China. One was determined by polyacrylamide gel isoelectric focusing (IEF) of neuraminidase-treated EDTA plasma, whereas the other was performed by a combination of two ELISAs using a C7-allospecific monoclonal antibody or polyclonal C7-specific IgG as coating antibodies. In 121 Chinese subjects IEF patterns of C7 were classified into three common and four rare phenotypes. The C7 IEF allele frequency estimates for C7*1, C7*2, C7*3, C7*4 and C7*7 were 0.831, 0.095, 0.045, 0.025 and 0.004, respectively. The C7 M/N typing in 113 Chinese individuals revealed the following allele frequencies: C7*M = 0.805, C7*N = 0.195. Allelic associations between C7 IEF alleles and the C7 M/N alleles are also discussed.

Asian People↗
PubMedDate not supplied

Polymorphism of the seventh component of complement (C7) in a healthy Caucasian population: an immunoblotting study with neuraminidase-treated samples.

Genetic polymorphism of the seventh component of complement (C7) was studied in a healthy Caucasian population using polyacrylamide gel isoelectric focusing of neuraminidase-treated plasma samples and an immunoblotting procedure for the specific detection of C7. Among 248 blood donors, three C7-3/1 heterozygotes were identified, resulting in a C7*3 allele frequency of 0.0061 +/- 0.0035. Neuraminidase treatment of serum or plasma samples is necessary for unequivocal identification of C7*3, which is known to be a hypomorphic variant. This observation is discussed with special reference to previous studies on C7 polymorphism in Caucasian populations, where untreated samples have been used for C7 typing.

Blotting, Western↗
PubMed2004

Complement C7 deficiency presenting as recurrent aseptic meningitis.

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.

Adult↗
PubMedDate not supplied

A common Ser/Thr polymorphism in the perforin-homologous region of human complement component C7.

Complement component C7 plays an important role in the formation of the membrane attack complex of the complement system. Here we describe a novel polymorphism of human C7, namely a nucleotide sequence polymorphism changing codon 367 from AGT (encoding Ser) to ACT (encoding Thr). Using the polymerase chain reaction, the polymorphism is easily detectable either as a MaeIII restriction fragment length polymorphism or by single-strand conformation analysis. The two alleles are both very common, probably in all major races.

Base Sequence↗
PubMed1975

Human complement C7 and C9 in fetal and newborn sera.

Using specific immune sera, C7, C9, and C3 activator were detected in sera from human fetuses more than 16 weeks old and in newborn samples. Levels of C9 in cord sera ranged between 10 and 30% of those present in sera from adult subjects. The mean value of Ce activator was about half that in maternal blood. The mean level of C7 in newborns was nearly 70% of the amount in normal adults.

Animals↗
PubMed1998

Complement C7 deficiency: seven further molecular defects and their associated marker haplotypes.

Seven further molecular bases of C7 deficiency are described. All these new molecular defects involve single-nucleotide events, deletions and substitutions, some of which alter splice sites, and others codons. They are distributed along the C7 gene, but predominantly towards the 3' end. All were found in compound heterozygous individuals. The C6/C7 marker haplotypes associated with most C7 defects are tabulated.

Complement C7↗
PubMed2002

C7 complement deficiency in an Israeli Arab village.

Deficiencies of terminal complement components, particularly the latter ones, are often detected because of increased susceptibility to Neisserial infections. Herein we document the first report of C7 deficiency among a highly inbred Arab population living in the lower Galilee region of Israel. Both biochemical and molecular analysis were performed on samples from infected survivors and parents of children who succumbed to Neisserial infections in a 4-year period. Only the index case who suffered recurrent infections and a sibling who had not suffered an infection during the outbreak were found to be C7-deficient. The mutation was found to be the one previously described to be prevalent among Israeli Jews of Moroccan ancestry (mutation G1135C). The implications of this finding are discussed in the context of family pedigree, the protective effect of complement deficiency, and the clinical outcome.

Adolescent↗