Abstract |
Hemolytic uremic syndrome (HUS) is a triad of microangiopathic hemolytic anemia, thrombocytopenia, and acute renal failure. HUS is classified as either diarrhea associated, most commonly caused by infection with Escherichia coli O157, or the less common atypical HUS (aHUS), which may be familial or sporadic. Approximately 50% of patients with aHUS have mutations in one of the complement control proteins: factor H, factor I, or membrane cofactor protein (MCP). These proteins regulate complement activation through cofactor activity, the inactivation of C3b by limited proteolytic cleavage, a desirable event in the fluid phase (no target) or on healthy self-tissue (wrong target). Complement activation follows the endothelial cell injury that characterizes HUS. This disease represents a model of what takes place when inappropriate complement activation occurs on self-tissues due to the presence of mutated complement regulatory proteins. Screening for mutations in factor H, factor I, or MCP is expensive and time consuming. One approach is to perform antigenic screening for factor H and factor I deficiency and to look for low levels of MCP (CD46) expression by flow cytometry. Complement regulatory protein deficiency impacts treatment decisions as patients with aHUS have a recurrence rate in renal transplants of approximately 50%, whereas those with factor H mutations have an even higher risk (approximately 80%). By contrast, MCP deficiency can be corrected in part by a renal allograft. However, caution in the use of live-related donations is needed because of the high rates of incomplete penetrance of the described mutations.
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Authors | John P Atkinson, M Kathryn Liszewski, Anna Richards, David Kavanagh, Elizabeth A Moulton |
Journal | Annals of the New York Academy of Sciences
(Ann N Y Acad Sci)
Vol. 1056
Pg. 144-52
(Nov 2005)
ISSN: 0077-8923 [Print] United States |
PMID | 16387683
(Publication Type: Journal Article, Review)
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Chemical References |
- Membrane Cofactor Protein
- Complement C3b
- Complement System Proteins
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Topics |
- Complement Activation
- Complement C3b
(physiology)
- Complement System Proteins
(physiology)
- Escherichia coli Infections
(complications)
- Hemolytic-Uremic Syndrome
(microbiology, physiopathology)
- Homeostasis
- Humans
- Membrane Cofactor Protein
(genetics)
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