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.
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.
Licht
Christoph
C
Division of Pediatric Nephrology, Children's Hospital of the University of Cologne, Cologne, Germany.
Weyersberg
Annic
A
Heinen
Stefan
S
Stapenhorst
Ludwig
L
Devenge
Jacqueline
J
Beck
Bodo
B
Waldherr
Ruediger
R
Kirschfink
Michael
M
Zipfel
Peter F
PF
Hoppe
Bernd
B
D017242:Complement Factor H / Q000172:deficiency* / Q000235:genetics*; D006463:Hemolytic-Uremic Syndrome / Q000235:genetics / Q000628:therapy*; D006801:Humans; D007231:Infant, Newborn; D008297:Male; D009154:Mutation / Q000235:genetics*; D010455:Peptides / Q000235:genetics*; D010951:Plasma Exchange / Q000379:methods*; D017434:Protein Structure, Tertiary / Q000235:genetics
C493495:CFH protein, human; D010455:Peptides; D017242:Complement Factor H