Membrane cofactor protein mutations in atypical hemolytic uremic syndrome (aHUS), fatal Stx-HUS, C3 glomerulonephritis, and the HELLP syndrome

Celia J. Fang, Veronique Fremeaux-Bacchi, M. Kathryn Liszewski, Gaia Pianetti, Marina Noris, Timothy H.J. Goodship, John P. Atkinson

Research output: Contribution to journalArticlepeer-review

105 Scopus citations

Abstract

The hemolytic uremic syndrome (HUS) is a triad of microangiopathic hemolytic anemia, thrombocytopenia, and renal impairment. Genetic studies demonstrate that heterozygous mutations of membrane cofactor protein (MCP;CD46) predispose to atypical HUS (aHUS), which is not associated with exposure to Shiga toxin (Stx). Among the initial 25 MCP mutations in patients with aHUS were 2, R69W and A304V, that were expressed normally and for which no dysfunction was found. The R69W mutation is in complement control protein module 2, while A304V is in the hydrophobic transmembrane domain. In addition to 3 patients with aHUS, the A304V mutation was identified in 1 patient each with fatal Stx-HUS, the HELLP (hemolysis, elevated liver enzymes, and low platelets) syndrome, and glomerulonephritis with C3 deposits. A major goal was to assess if these putative mutations lead to defective complement regulation. Permanent cell lines expressing the mutated proteins were complement "challenged," and membrane control of C3 fragment deposition was monitored. Both the R69W and A304V MCP mutations were deficient in their ability to control the alternative pathway of complement activation on a cell surface, illustrating the importance of modeling transmembrane proteins in situ.

Original languageEnglish
Pages (from-to)624-632
Number of pages9
JournalBlood
Volume111
Issue number2
DOIs
StatePublished - Jan 15 2008

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