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PubMed1976

Effects of endotoxin in cortisone-treated rabbits with a hereditary deficiency of the sixth component of complement (C6 deficiency).

Endotoxin was infused into normal rabbits and C6 deficient rabbits prepared with cortisone for the generalized Shwartzman reaction. Endotoxin produced profound granulocytopenia and moderate thrombocytopenia in both normal and C6 deficient rabbits. In normal rabbits endotoxin consistently produced extensive intravascular clotting. In C6 deficient animals endotoxin resulted in intravascular clotting of variable extent. In one group of eight C6 deficient rabbits mean fibrinogen levels fell 0.67 g per 1 over 6 hrs after endotoxin and four of eight animals developed a generalized Shwartzman reaction. In a second group of seven C6 deficient rabbits mean fibrinogen level fell only 0.17 g per 1 over 6 hrs and one animal developed a generalized Shwartzman reaction. Values for mean fibrinogen consumption, calculated from plasma fibrinogen levels and rate of disappearance of 25I-fibrinogen, were as follows: normal animals infused with saline, 10 mg per kg; C6 deficient animals infused with endotoxin, 58 mg per kg. Fibrinogen consumption after endotoxin was found to be related to granulocyte levels prior to endotoxin, which determined the number of granulocytes disappearing from the blood after endotoxin. The data indicate that C6 deficiency in the rabbit does not prevent intravascular clotting and the generalized Shwartzman reaction.

Agranulocytosis↗
PubMed1989

Complement C6 and C7 polymorphisms in Japanese patients with chronic glomerulonephritis.

C6 and C7 types were studied in 158 Japanese patients with different types of chronic glomerulonephritis: 75 patients with IgA nephropathy (IgA-N); 49 patients with idiopathic membranous nephropathy (IMN), and 34 patients with minimal-change nephrotic syndrome (MCNS). There were significant differences in the C6 and C7 allele and phenotype frequencies between the patient groups and controls. A strong association was found between IgA-N and C7 5 phenotype (p less than 0.001, RR = 12.71), and between MCNS and C7 5 phenotype (p less than 0.001, RR = 14.20). A significant association between MCNS and C6 B2 phenotype (p less than 0.05, RR = 2.42) was also found. In the IMN patient group, a significant association with C7 4 phenotype (p less than 0.05, RR = 2.42) was observed. Thus, C6 and C7 phenotypes may be causative factors in the development of chronic glomerulonephritis.

Complement C6↗
PubMed1996

Complement C6 and C7 DNA polymorphisms analysed by PCR in seven ethnic groups and characterisation of the C6 MspI RFLP.

Five polymorphisms in the C6 and C7 genes have been investigated in seven ethnic groups. The allele frequencies are broadly similar in most groups except C7 M/N which is monomorphic in our group of Africans, and C6 MspI and C7 S367T where the allele frequencies in African and Cape Coloured subjects are very different from the other ethnic groups. There is very little allelic association except between C6 A/B and C6 MspI. Seventeen of the 32 possible haplotypes have been observed, suggesting that much recombination has taken place. We describe a new method for the investigation of the MspI RFLP located in intron 3 of C6 (approximately 3 kbp 3' from exon 3 and 1.5 kbp 5' from exon 4) and its molecular basis, together with an improved method for the isolation of DNA from stored serum.

Alleles↗
PubMed1995

DNA polymorphisms of the complement C6 and C7 genes.

The linked C6 and C7 loci are rich in genetic markers, both at the protein and DNA levels. There are now seven common DNA polymorphisms distributed over about 300 kbp of chromosome 5p12-14. We report a new TaqI RFLP for C7 and a method for typing a C7 variant (T368S) hitherto known only from cDNA clones. We have re-investigated the published RFLPs to provide information on their frequency in North European Caucasian (predominantly British and Irish) subjects and have revised some of the published parameters, especially the sizes of polymorphic restriction fragments. Their precise locations within the genes are also reported: the three markers for C6 are in exon 3, intron 3 and adjacent to exon 17 and the four markers for C7 are in introns 15 and 13 and in exons 13 and 9. The gene frequencies of the second commonest allele of all seven markers lie in the range 0.2 to 0.37, except C6 A/B in the Japanese, where the frequencies of both common alleles are about 0.45. We have estimated the gene frequencies for the DNA polymorphisms which correlate with C7 M/N phenotype and for the C6 A/B phenotype and find them to be the same as the phenotypic estimates in Caucasians and in the Japanese respectively. The markers provide the possibility of defining 128 haplotypes, many (28) of which have been observed. Allelic associations in these genes are generally surprisingly weak.

Alleles↗
PubMed1997

DNA haplotypes of the complement C6 and C7 genes associated with deficiencies of the seventh component; and a new DNA polymorphism in C7 exon 13.

Eight common DNA polymorphisms have been described for the linked C6 and C7 genes. We now describe a ninth polymorphism in C7 exon 13 which is located in a tight cluster with two previously reported markers. We have used all these markers to investigate the heterogeneity of C7 deficiency. Five of the nine C7 deficient probands (resident in Ireland, South Africa, Russia and Israel) are heterozygous for C6/C7 haplotypes. Seven different C7 deficient haplotypes were found for C7 markers alone, but all the four Israelis share one and three out of four Irish haplotypes share another. The markers appear to be a good guide to the heterogeneity of C7 deficiency and have been useful in choosing homozygous subjects for the investigation of molecular defects.

Child↗
PubMed2003

Single nucleotide polymorphisms in the human complement C6 and C7 genes.

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.

Complement C6↗
PubMed1997

Complement C6 and C2 biosynthesis in syngeneic PVG/c- and PVG/c+ rat strains.

A PVG rat with total deficiency of C6 and partial deficiency of C2 (PVG/c-), and a syngeneic control strain (PVG/c+), were used to study the production of extrahepatically synthesized complement. Livers of complement deficient rats were transplanted in sufficient rats (Tx-L). The C6 and C2 levels in Tx-L rats declined within 2 days to 25% and 30%, respectively, and remained stable for more than 6 weeks. To investigate the contribution of C6 synthesis by the liver, C6 sufficient livers were grafted in deficient rats (Tx + 1). After an initial increase, with maximum C6 levels of 119% at 10 days following transplantation, the C6 levels decreased gradually and C6 was no longer detectable 28 days after transplantation. This decline in C6 levels was dependent on antibody production against C6. No significant change in the C3, C4, factor H and factor B levels was observed. Expression of C6 mRNA in the grafted PVG/c+ sufficient liver was comparable to the expression of C6 mRNA in control PVG/c+ livers while C6 mRNA expression in the transplanted PVG/ c- liver and the control PVG/c- liver was lower. In conclusion, it was demonstrated in vivo that not only C6 but also C2 is synthesized extrahepatically in PVG/c rats.

Animals↗
PubMed1979

Further evidence for independent segregation of the HLA system and a structural gene for the sixth component of complement (C6).

Previous studies have shown conflicting results with respect to the relationship between C6 deficiency and the HLA system. The present investigation of two kinships, in which C6 deficiency was associated with the expression of an amorphic (or silent) C6 allele, has provided further evidence for the genetic independence of a structural C6 locus and the HLA system.

Adult↗
PubMed1988

Forensic application of blood stains and polymorphism of the sixth component of human complement (C6).

Blood samples from 340 unrelated individuals in Fukui prefecture in the central part of Japan were tested in order to determine the gene frequencies of the C6 common alleles. The gene frequencies calculated were as follows: C6 A, 0.478, C6 B, 0.464, C6 B2, 0.052 and rare alleles, 0.006. It was demonstrated that C6 phenotyping from blood stains aged over a period of 1 year, could be performed correctly. The quantity of detectable whole blood after this period amounted to less than 2 microliter.

Alleles↗
PubMed1987

Hereditary complement (C6) deficiency associated with systemic lupus erythematosus, Sjögren's syndrome and hyperthyroidism.

Results of clinical, serologic and histologic studies documenting an association between hereditary C6 deficiency and a connective tissue disease are provided. The propositus had systemic lupus erythematosus with prominent discoid features, Sjögren's syndrome and hyperthyroidism. Serum C6 was undetectable by radial immunodiffusion and hemolytic assays. Serologic and typing studies performed on 9 family members suggested an autosomal codominant transmission. No correlation with a specific HLA phenotype was established.

Complement C6↗
PubMed1979

Genetic linkage relations of the sixth component of complement (C6).

Linkage relations between the C6 and 33 other genetic marker loci have been analyzed in Norwegian pedigrees, including 114 matings with 388 informative children, by use of the MOSM computer program. No suggestion of linkage was found. Very close or close linkage (theta less than 0.06) has been ruled out for males between C6 and the following 19 marker loci: GPT, HLA + Bf, Rh, C3, Hp, PGM3, Km, Gm, Fy, Gc, ABO Jk, GLO1, K, MNSs, PTC, ACP1, PGM1, and Pi. For several of the relations even loose-linkage is unlikely.

Adult↗
PubMed1984

Genetic polymorphism of the sixth component of complement (C6) in mice.

Immunofixation after isoelectric focusing revealed two forms of mouse C6, C6A and C6M, both of which consist of two major protein bands and one or more acidic minor bands. They were distinguishable by their different isoelectric point (pI) ranges: C6M has more acidic pI ranges (pH less than 6.2) than C6A (pH less than 6.3). C6A was found in common inbred mice of Mus musculus domesticus, while C6M was found in inbred and wild mice of M. m. molossinus (Japanese wild mice, an Asian subspecies). Breeding experiments showed that these two forms of C6 were controlled by a single codominant autosomal locus. We propose the designation C-6 for this locus with two alleles, C-6a and C-6m, which encode for C6A and C6M, respectively. Linkage analysis indicated that the locus is not closely linked to the following loci: Idh-1, agouti, Amy-1, brown, Gpd-1, Mup-1, Pgm-2, Pgm-1, albino, Hbb, Es-1, Mod-1, Sep-1, Es-3, Igh-1, beige, Es-10, Sod-1, and C-3.

Animals↗