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Prophylactic plasma exchange in CD46-associated atypical haemolytic uremic syndrome.

ABSTRACT: Patients with atypical haemolytic uremic syndrome (aHUS) with a mutation in the gene encoding membrane cofactor protein (CD46) are known to have a better prognosis than those with mutations in factor H (CFH) or factor I (CFI), but a small number of the former still proceed to end-stage renal failure. Plasma therapy (PE) is the recommended approach to treat both acute episodes and prevent recurrences in aHUS, but studies have yet to show PE efficacy in aHUS associated with a CD46 mutation. The factors determining failure to treatment are not clear and may be related to the mutation involved or to insufficient treatment. Our experience of PE in a family of three sisters with CFH-associated aHUS suggests that intensive and prophylactic PE allows renal function to be maintained in both native kidneys and allografts. The success of this strategy has led us to use it in all cases of aHUS. Here, we describe the effect of this strategy in a child with aHUS and a CD46 mutation. The initial episode was treated with daily PE, resulting in the recovery of renal function. However, over the next 4 years, there was a progressive decline in renal function to end-stage renal failure, with evidence of an on-going thrombotic microangiopathy despite continuous prophylactic PE. Prophylactic PE does not influence the natural course of aHUS and CD46 mutation.

SUBMITTER: Davin JC

PROVIDER: S-EPMC2719744 | biostudies-literature | 2009 Sep

REPOSITORIES: biostudies-literature

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Prophylactic plasma exchange in CD46-associated atypical haemolytic uremic syndrome.

Davin Jean-Claude JC Buter Nynke N Groothoff Jaap J van Wijk Joanna J Bouts Antonia A Strain Lisa L Goodship Tim T

Pediatric nephrology (Berlin, Germany) 20090417 9

Patients with atypical haemolytic uremic syndrome (aHUS) with a mutation in the gene encoding membrane cofactor protein (CD46) are known to have a better prognosis than those with mutations in factor H (CFH) or factor I (CFI), but a small number of the former still proceed to end-stage renal failure. Plasma therapy (PE) is the recommended approach to treat both acute episodes and prevent recurrences in aHUS, but studies have yet to show PE efficacy in aHUS associated with a CD46 mutation. The fa ...[more]

PMID: 19373492

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Project description:IntroductionComprehensive genetic analysis is essential to clinical care of patients with atypical haemolytic uremic syndrome (aHUS) to reinforce diagnosis, and to guide treatment. However, the characterization of complement gene variants remains challenging owing to the complexity of functional studies with mutant proteins. This study was designed: 1) To identify a tool for rapid functional determination of complement gene variants; 2) To uncover inherited complement dysregulation in aHUS patients who do not carry identified gene variants.MethodsTo address the above goals, we employed an ex-vivo assay of serum-induced C5b-9 formation on ADP-activated endothelial cells in 223 subjects from 60 aHUS pedigrees (66 patients and 157 unaffected relatives).ResultsSera taken from all aHUS patients in remission induced more C5b-9 deposition than control sera, independently from the presence of complement gene abnormalities. To avoid the possible confounding effects of chronic complement dysregulation related to aHUS status, and considering the incomplete penetrance for all aHUS-associated genes, we used serum from unaffected relatives. In control studies, 92.7% of unaffected relatives with known pathogenic variants exhibited positive serum-induced C5b-9 formation test, documenting a high sensitivity of the assay to identify functional variants. The test was also specific, indeed it was negative in all non-carrier relatives and in relatives with variants non-segregating with aHUS. All but one variants in aHUS-associated genes predicted in-silico as likely pathogenic or of uncertain significance (VUS) or likely benign resulted as pathogenic in the C5b-9 assay. At variance, variants in putative candidate genes did not exhibit a functional effect, with the exception of a CFHR5 variant. The C5b-9 assay in relatives was helpful in defining the relative functional effect of rare variants in 6 pedigrees in which the proband carried more than one genetic abnormality. Finally, for 12 patients without identified rare variants, the C5b-9 test in parents unmasked a genetic liability inherited from an unaffected parent.DiscussionIn conclusion, the serum-induced C5b-9 formation test in unaffected relatives of aHUS patients may be a tool for rapid functional evaluation of rare complement gene variants. When combined with exome sequencing the assay might be of help in variant selection, to identify new aHUS-associated genetic factors.

Project description:To describe a case of atypical hemolytic uremic syndrome induced by influenza A infection with the p.Ile1157Thr C3 mutation.Data sourcesClinical observations of a patient.Study selectionCase reports.Data extractionData extracted from medical records, after patient's consent.Data synthesisFour days prior to presentation to our hospital, a 16-year-old adolescent had a fever and arthralgia with hematuria. He was found to be positive for type A influenza and prescribed oseltamivir and acetaminophen by a primary-care physician. A bleeding tendency and purpura in the extremities and on the trunk developed; therefore, he was transferred to Chiba University Hospital. Hematology revealed severe thrombocytopenia, hyperbilirubinemia, and acute kidney injury. Aspartate aminotransferase, lactate dehydrogenase, and potassium could not be determined because of severe hemolysis. Highly elevated blood urea nitrogen and creatinine levels indicated acute kidney injury. A platelet count of 24,000/μL indicated thrombocytopenia, with low hemoglobin level. Peripheral blood profiling identified schistocytes. Continuous hemodiafiltration and plasma infusion were initiated immediately; however, he became oliguric. Plasma exchange was initiated on ICU day 3, but decreased urine output, hemolysis, and thrombocytopenia persisted. IV eculizumab therapy was initiated on day 7 and resulted in recovery of these symptoms and also successful discontinuation of renal support. The patient showed a stable condition without recurrence of hemolytic findings and acute kidney injury and is currently on maintenance therapy of eculizumab (1,200 mg, every other week) without any relapse of atypical hemolytic uremic syndrome symptoms. A plasma sample collected prior to initiation of plasma exchange showed an disintegrin-like and metalloprotease with thrombospondin type 1 motifs 13 activity level of 104.9%. The absence of both Shiga toxin-producing Escherichia coli in feces led to suspicion of atypical hemolytic uremic syndrome. Subsequent genetic analysis identified a mutation in C3 (p.Ile1157Thr), confirming the diagnosis of atypical hemolytic uremic syndrome.ConclusionsAlthough managing thrombocytopenia secondary to infection, inclusion of atypical hemolytic uremic syndrome in the differential diagnosis at an early stage is important in clinical practice.

Dataset Information

Prophylactic plasma exchange in CD46-associated atypical haemolytic uremic syndrome.

Publications

Prophylactic plasma exchange in CD46-associated atypical haemolytic uremic syndrome.

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