Rare genetic variant in the CFB gene presenting as atypical hemolytic uremic syndrome and immune complex diffuse membranoproliferative glomerulonephritis, with crescents, successfully treated with eculizumab

Pediatr Nephrol. 2017 May;32(5):885-891. doi: 10.1007/s00467-016-3577-0. Epub 2017 Feb 16.

Abstract

Background: Complement factor B gene (CFB) is an important component of the alternate pathway of complement activation that provides an active subunit that associates with C3b to form the C3 convertase, which is an essential element in complement activation. Among the complement-associated disorders, mutations and pathogenic variants in the CFB gene are relatively rare phenomena. Moreover, mutated CFB affiliation with immune-complex diffuse membranoproliferative glomerulonephritis (IC-MPGN) and atypical hemolytic uremic syndrome (aHUS) are considered a highly rare occurrence.

Case presentation: We describe the clinical presentation, course, and pathological findings in a 7-year-old boy who has confirmed CFB heterozygous variants with pathological features compatible with IC-MPGN. Mutational analysis revealed a heterozygous variant p.Glu566Arg in exon 13 of the CFB gene. The patient did not respond to steroids and mycophenolate mofetil (MMF) therapy but responded clinically and biochemically to eculizumab treatment. This is the first case report of CFB alteration associated with IC-MPGN and aHUS that was successfully treated with eculizumab.

Conclusions: Heterozygous variants in the CFB gene can be pathogenic and associated with IC-MPGN and aHUS. Early diagnosis and prompt management can be essential in preventing end-stage renal disease. Eculizumab may provide an effective modality of treatment.

Keywords: Atypical hemolytic uremic syndrome; CFB gene; Complement factor B; Eculizumab; Immune-complex-mediated diffuse membranoproliferative glomerulonephritis.

MeSH terms

  • Antibodies, Monoclonal, Humanized / therapeutic use*
  • Child
  • Complement C3 / analysis
  • Complement Factor B / genetics*
  • Creatinine / blood
  • DNA Mutational Analysis
  • Exons / genetics
  • Glomerulonephritis, Membranoproliferative / drug therapy*
  • Glomerulonephritis, Membranoproliferative / genetics*
  • Glomerulonephritis, Membranoproliferative / pathology
  • Hemolytic-Uremic Syndrome / drug therapy*
  • Hemolytic-Uremic Syndrome / genetics*
  • Humans
  • Kidney Failure, Chronic / prevention & control
  • Kidney Function Tests
  • Male
  • Mutation

Substances

  • Antibodies, Monoclonal, Humanized
  • Complement C3
  • eculizumab
  • Creatinine
  • Complement Factor B