Atypical Hemolytic Uremic Syndrome

Clinicians should suspect thrombotic microangiopathy (TMA) in front of microangiopathic hemolytic anemia, thrombocytopenia (or platelet consumption), and organ damage. Atypical hemolytic uremic syndrome (aHUS) is an ultra-rare but devastating form of TMA. aHUS diagnosis is very complicated given its variable clinical presentation (multi-system involvement) and the absence of laboratory tests that allow its inclusive identification (clinical diagnosis by exclusion of all other TMA forms). The endothelial damage that trigger TMA in aHUS patients is mediated by a dysregulation of the alternative complement pathway. Acquired (15% of cases, due to antibodies against factor-H) or inherited, 40–60% of cases present genetic variants in complement genes. Gold standard treatment consists of early introduction of terminal complement blockade (monoclonal antibodies against C5 molecule).