Recurrent Postpartum Atypical Hemolytic Uremic Syndrome Caused by a C3 Pathogenic Variant: A Case Report.

Background: Atypical hemolytic uremic syndrome (aHUS) is a life-threatening thrombotic microangiopathy (TMA) driven by uncontrolled activation of the complement alternative pathway. Pregnancy and postpartum period are well-recognized triggers for aHUS. In recent years, the prognosis of aHUS has substantially improved with the use of complement-targeted therapies. However, timely recognition, accurate classification, and prompt treatment initiation remain critical. This report describes a case of postpartum aHUS caused by a C3 gene mutation that achieved complete clinical and laboratory remission following a treatment strategy that included early eculizumab, plasma infusion, and renal replacement therapy. Drawing on the literature, we discuss key diagnostic and therapeutic considerations as well as clinical implications to provide guidance for clinical practice. Case Presentation: We present a 35-year-old multiparous woman (gravida 3, para 3) who developed acute kidney injury, microangiopathic hemolytic anemia, and severe thrombocytopenia 2 days after cesarean section. She had a history of similar TMA episode 8 years postpartum. Laboratory investigations showed normal ADAMTS13 activity, negative autoimmune antibodies, reduced serum complement C3 and factor I levels, and elevated sC5b-9. Whole-exome sequencing identified a heterozygous pathogenic mutation in the Conclusion: This case highlights that