title: Evaluation of complement regulatory components in patients with atypical hemolytic uremic syndrome.
abstract: BACKGROUND
  Atypical hemolytic uremic syndrome (aHUS), a rare disorder characterized by thrombocytopenia, microangiopathic hemolytic anemia, and acute renal failure, is associated with mutations and polymorphisms in various components and regulators of the complement alternative pathway (AP), including factor H, factor I, membrane cofactor protein (MCP or CD46) and factor B. This impaired regulation of the alternative pathway leads to a procoagulant state with microthrombi formation in the renal vasculature, which influences disease onset and progression.
  
  
  OBJECTIVE
  To evaluate the role of complement regulatory factors in occurrence of aHUS; we also included evaluation of ADAMTS13 activity and autoantibody against ADAMTS13 in order to exclude thrombotic thrombocytopenic purpura (TTP) cases, which might have overlapping clinical and laboratory findings.
  
  
  METHODS
  This study was conducted on 273 individuals with aHUS. Diagnosis was based on clinical manifestations, kidney function tests, red blood cell count, morphology and reticulocyte count. Then, the ADAMTS 13 autoantibody and activity and also complement factor B, complement factor H (CFH) and complement factor-I (CIF) were analyzed. Finally, the statistical analysis was performed by SPSS software.
  
  
  RESULTS
  The mean age of our patients was 27.3 years, 55% were female and 45% were male. The mean levels of urea and creatinine concentration were 92.9 mg/dl and 5.1 mg/dl, respectively. The mean levels of RBC count, Hb and HCT in these patients were lower than normal but the mean percentage of reticulocyte count was higher than normal (2.5%). The assessment of complement regulatory factors revealed that the B and H factors levels were normal except in two cases but the level of factor I was higher than normal.
  
  
  CONCLUSIONS
  According to the results of this study, it seems that up regulation of factor I had a significant role in occurrence of aHUS in our study group.
authors.affiliation: Hematology and Flow Cytometry Laboratory, Ali Asghar Children Hospital, Iran University of Medical Sciences, Tehran, Iran ; Laboratory Director, Gholhak Clinical Laboratory Tehran, Iran.
authors.forename: Hosseini
authors.initials: H
authors.lastname: Soudabeh
authors.affiliation: Laboratory Director, Gholhak Clinical Laboratory Tehran, Iran ; Department of Immunology, School of Allied Health Science, Iran University of Medical Sciences, Tehran, Iran.
authors.forename: Kalantar
authors.initials: K
authors.lastname: Ebrahim
authors.affiliation: Paediatric Nephrology Ward, Ali Asghar Children Hospital, Iran University of Medical Sciences, Tehran, Iran.
authors.forename: Hooman
authors.initials: H
authors.lastname: Nakisa
authors.affiliation: Department of Hematology, School of Allied Health Science, Iran University of Medical Sciences, Tehran, Iran.
authors.forename: Dorgalaleh
authors.initials: D
authors.lastname: Akbar
authors.affiliation: Paediatric Nephrology Ward, Ali Asghar Children Hospital, Iran University of Medical Sciences, Tehran, Iran.
authors.forename: Hosseini Shamsabadi
authors.initials: HS
authors.lastname: Rozita
authors.affiliation: Infection Diseases and Tropical Medicine Research Center, Zahedan University of Medical Sciences, Zahedan, Iran.
authors.forename: Taregh
authors.initials: T
authors.lastname: Bamedi
keywords: ADAMTS 13; ADAMTS autoantibody; atypical hemolytic uremic syndrome; factor I