C4B deficiency in two siblings with IgA nephropathy

Am J Kidney Dis. 1990 Jan;15(1):66-71. doi: 10.1016/s0272-6386(12)80594-4.


The development of IgA nephropathy in first degree relatives is a well-described, yet relatively uncommon, occurrence. The association of a C4 isotype deficiency or partial deficiency of another complement protein has been previously documented for patients with IgA nephropathy. The present report describes a family in which two siblings and their father had biopsy-confirmed IgA nephropathy; both siblings were deficient for the C4B isotype. In addition, one of the biopsied siblings and a third sibling with microscopic hematuria but no renal biopsy apparently had a partial deficiency of the complement regulatory protein, I. The findings in this family may be compatible with the hypothesis that a C4 isotype deficiency and/or a partial deficiency of an individual complement protein allows clinical expression of IgA nephropathy in an individual with a genetic susceptibility for the disease.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adolescent
  • Adult
  • Afibrinogenemia / complications
  • Afibrinogenemia / genetics
  • Complement C4a / analysis
  • Complement C4a / genetics
  • Complement C4b / deficiency*
  • Electrophoresis, Agar Gel
  • Female
  • Glomerulonephritis, IGA / complications
  • Glomerulonephritis, IGA / genetics
  • Glomerulonephritis, IGA / immunology*
  • Haplotypes / genetics
  • Humans
  • Male
  • Middle Aged
  • Pedigree
  • Phenotype


  • Complement C4a
  • Complement C4b