Genetic analysis of C4 deficiency.

Awdeh, Zuheir L.; Ochs, HansD.; Alper, C. A.

doi:10.1172/jci110021

Cited by 46 publications

(21 citation statements)

References 15 publications

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“…In contrast to total C4 deficiency, C4R QL is inherited as an autosomal dominant trait, does not show the MHC linkage typical of complete C4 deficiency, and is not caused by null C4 alleles. Although most affected members of this kindred have 1 null allele, this condition does not lead to an abnormal level of C4 in serum (16,17). More importantly, 1 C4-deficient member (111-6) was found to have 4 expressed C4 genes.…”

Section: Discussionmentioning

confidence: 80%

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Metabolism of C4 and linkage analysis in a kindred with hereditary incomplete C4 deficiency

Wisnieski

Nathanson

Anderson

et al. 1987

Arthritis & Rheumatism

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We studied a kindred in which C4 deficiency had been discovered. Unlike families with total absence of C4, in this kindred C4 deficiency was found to be incomplete, autosomal dominant, not caused by null alleles, and not associated with a high incidence of systemic lupus erythematosus. The deficient state was caused by hyposynthesis of C4, not by hypercatabolism. The locus for incomplete C4 deficiency was not closely linked to the major histocompatibility complex. The abnormal autosomal dominant allele is, apparently, rare, and how it causes decreased synthesis of C4 is unknown.

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Section: Discussionmentioning

confidence: 80%

“…In the usual form of hereditary C4 deficiency, affected individuals have no detectable C4 and are homozygous for a double-null (C4A*QO, C4B*QO) C4 haplotype (16). Because the structural genes for C4 are located within the MHC, complete C4 deficiency is linked to the genes of the MHC, including HLA and other genes involved in the immune response.…”

mentioning

confidence: 99%

Metabolism of C4 and linkage analysis in a kindred with hereditary incomplete C4 deficiency

Wisnieski

Nathanson

Anderson

et al. 1987

Arthritis & Rheumatism

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“…a method later refined by enzyme digestion of C4 which simplifies the banding pattern of C4 on gel electrophoresis [19]. Previous studies have shown a reduction of total C4 associated with the presence of null alleles [20][21][22]. Reference ranges for the identification of genetic deficiency have been suggested [23] and densitometry of eleetrophoretic bands has been used to quantify C4 isotype levels and to estimate the presence of homoduplicated C4 loci [24].…”

Section: Discussionmentioning

confidence: 99%

Effects of C4 null alleles and homoduplications on quantitative expression of C4A and C4B

Hammond

Ollier

Walport

1992

Clinical and Experimental Immunology

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SUMMARYThe availability of MoAbs now allows the accurate quantification of the individual C4 isotypes, C4A and C4B. Using a sensitive two-site immunoradiometric technique to measure serum levels of C4A and C4B, we studied the relationship between genotype and phenotype and physiological factors affecting C4 expression in 129 fully gcnotyped healthy subjects. Our results confirm that there is extensive phenotypic overlap between genotypic groups and it was not possible to determine the presenee of single null alleles from total serum C4. Of the factors which may influence C4 expression, we found that age conttibutes a very small influence but that gender has no effect and there was no evidence for the presence of feedback of null alleles on the expression of remaining genes. Potential problems in quantifying C4 arising from the complex relationship between isotypic identity and serotypic recognition were highlighted by ihe finding of reversed antigenic expression ofa C4B*5 molecule which was recognized as C4A by the anti-Rg:

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“…When C4 typing was performed in a family with a child with classical C4 deficiency (16), it was shown conclusively that the deficiency resulted from homozygosity for a doublenull C4 haplotype, C4A*QO, C4B*QO, closely linked to other loci of the MHC, including HLA. Subsequent studies have confirmed these findings (10,17).…”

Section: Introductionmentioning

confidence: 99%

Inherited incomplete deficiency of the fourth component of complement (C4) determined by a gene not linked to human histocompatibility leukocyte antigens.

Muir¹,

Hedrick²,

Alper³

et al. 1984

J. Clin. Invest.

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Abstract. We have studied a family in which the proband had systemic lupus erythematosus and selective incomplete deficiency of the fourth component of complement (C4) (2-5% of the normal level). An additional six healthy family members also had low C4 levels (2.4-24.1% of normal) but no evidence of lupus. This form of inherited C4 deficiency differs from that in previously reported families in that inheritance was autosomal dominant (rather than recessive), C4 levels were markedly reduced (but not undetectable), and there was no linkage to HLA, BF, or C4 structural loci, all known to be within the major histocompatibility complex.

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Genetic analysis of C4 deficiency.

Cited by 46 publications

References 15 publications

Metabolism of C4 and linkage analysis in a kindred with hereditary incomplete C4 deficiency

Metabolism of C4 and linkage analysis in a kindred with hereditary incomplete C4 deficiency

Effects of C4 null alleles and homoduplications on quantitative expression of C4A and C4B

Inherited incomplete deficiency of the fourth component of complement (C4) determined by a gene not linked to human histocompatibility leukocyte antigens.

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