Atypical hemolytic uremic syndrome is an ultra-rare disease characterized by acute kidney injury, thrombocytopenia, and microangiopathic hemolytic anemia (thrombotic microangiopathy) that occurs with a reported incidence of approximately 0.5 per million per year.
At least 50% of patients with aHUS have an underlying inherited and/or acquired complement abnormality, which leads to dysregulated activity of the alternative pathway at the endothelial cell surface.
Until recently, the prognosis for aHUS was poor, with the majority of patients developing end-stage renal disease within 2 years of presentation. However, with the introduction of eculizumab, a humanized monoclonal antibody against C5, effective to inhibit complement-mediated thrombotic microangiopathy, it is now possible to control the renal disease and prevent development of end-stage renal disease.
Dosing schedule and treatment duration remain controversial and should be rigorously studied.
On this regard, C5b-9 endothelial deposition assay may represent an advance to monitor complement activity in aHUS and to individualize therapy, but currently it can be performed in only specialized laboratories.
Keywords: Atypical hemolytic uremic syndrome, complement, anti-C5 monoclonal antibody, C5b-9 assay