Successful plasma therapy for atypical hemolytic uremic syndrome caused by factor H deficiency owing to a novel mutation in the complement cofactor protein domain 15

Am J Kidney Dis. 2005 Feb;45(2):415-21. doi: 10.1053/j.ajkd.2004.10.018.

Abstract

Quantitative or functional deficiency of complement factor H results in uncontrolled complement activation. This leads to thrombotic microangiopathy and finally causes renal failure (atypical hemolytic uremic syndrome [aHUS]). By regular analysis of factor H in patients with aHUS, the authors found a complete factor H deficiency in an infant in whom aHUS developed at 8 months of age. Factor H was quantified by enzyme-linked immunosorbent assay and further analyzed by Western blot using a factor H-specific antibody. Complement activation was determined by measuring total hemolytic activity of the classical (CH50) and alternative (APH50) pathways, C3 and C3d. The sequence of factor H gene was determined. Serial factor H measurements after fresh frozen plasma infusion allowed calculation of a factor H half-life. Factor H was absent in plasma (<1 mug/mL), and the complement system was highly activated (CH50, APH50, C3 decreased; C3d increased). Genetic analysis identified a novel homozygous factor H mutation (T2770A; Y899Stop) in CCP domain 15, most likely causing defective protein secretion. Time course measurements of factor H after plasma infusion established a factor H half-life of about 6 days. By repetitive plasma infusions (20 mL/kg over about 2 to 3 hours) the authors were able to interrupt the vicious circle of thrombotic microangiopathy in a factor H-deficient patient with aHUS. Based on the measured factor H half-life of about 6 days, regular plasma infusions in 2-week intervals were given, which prevented further aHUS episodes and stopped the decline of kidney function.

Publication types

  • Case Reports

MeSH terms

  • Complement Factor H / deficiency*
  • Complement Factor H / genetics*
  • Hemolytic-Uremic Syndrome / genetics
  • Hemolytic-Uremic Syndrome / therapy*
  • Humans
  • Infant, Newborn
  • Male
  • Mutation / genetics*
  • Peptides / genetics*
  • Plasma Exchange / methods*
  • Protein Structure, Tertiary / genetics

Substances

  • Peptides
  • complement factor H, human
  • Complement Factor H