title: C4A deficiency and poor prognosis in patients with IgA nephropathy.
abstract: IgA nephropathy (Berger's disease) is an important cause of end-stage renal failure in persons of Asian and European descent. We performed C4 phenotyping on plasma from 123 patients with IgA nephropathy who resided in several different parts of the United States. All of these patients underwent diagnostic renal biopsy in adulthood. Six patients had a total deficiency for the C4A protein and all six had chronic renal insufficiency (serum creatinine concentration higher than 1.4 mg/dl at last follow-up). In contrast, 47% of the patients without C4A deficiency had chronic renal insufficiency (p = 0.001). The C4 gene defect was due to deletion of both C4A genes in only two individuals, whereas three patients were heterozygous for the C4A gene deletion. We speculate that the functional alteration of the complement system related to C4A deficiency might lead to expression of clinically severe disease in an individual with a genetic susceptibility to IgA nephropathy.
authors.affiliation: Department of Pediatrics, University of Tennessee, Memphis.
authors.forename: R J
authors.initials: RJ
authors.lastname: Wyatt
authors.forename: B A
authors.initials: BA
authors.lastname: Julian
authors.forename: S Y
authors.initials: SY
authors.lastname: Woodford
authors.forename: C
authors.initials: C
authors.lastname: Wang
authors.forename: J
authors.initials: J
authors.lastname: Roberts
authors.forename: J S
authors.initials: JS
authors.lastname: Thompson
authors.forename: M J
authors.initials: MJ
authors.lastname: Christenson
authors.forename: R H
authors.initials: RH
authors.lastname: McLean
mesh_terms: D002872:Chromosome Deletion; D015934:Complement C4a / Q000172:deficiency* / Q000235:genetics; D005260:Female; D020022:Genetic Predisposition to Disease; D005922:Glomerulonephritis, IGA / Q000235:genetics / Q000276:immunology*; D006650:Histocompatibility Testing; D006801:Humans; D016130:Immunophenotyping; D007676:Kidney Failure, Chronic / Q000235:genetics / Q000276:immunology*; D008297:Male; D011379:Prognosis
chemical_list: D015934:Complement C4a