Atypical Hemolytic Uremic Syndrome Presenting as Pre-eclampsia in a 24-year-old Woman with Chronic Kidney Disease: Pathogenesis and Genetics

Abstract

Atypical hemolytic uremic syndrome (aHUS) is a kidney disorder that is frequently unrecognized during its progression, and misdiagnosed with more common etiologies of microangiopathic hemolytic anemia (MAHA): hemolytic uremic syndrome, disseminated intravascular coagulation, and thrombotic thrombocytopenic purpura (TTP). During pregnancy, the diagnosis of aHUS is furthermore challenging. The clinical presentation of aHUS may mimic pre-eclampsia as it occurred to the patient described in the case report. However, the persistence of thrombocytopenia in the patient after dilatation of the cervix and surgical evacuation of the contents of the uterus has led to consider aHUS. The pathogenesis of aHUS provides clues to understanding the insidious progression and the variability of clinical presentations of the disease. aHUS is primarily a kidney disorder that results from genetic defects of the alternative complement pathway (AP). Consequently, Eculizumab, a monoclonal antibody that targets the AP, induced remission in the patient. A single gene defect of the AP cannot cause the clinical manifestation of aHUS alone. Most of aHUS patients have a combination of mutation, haplotype, and single nucleotide polymorphism. Often, an identifiable environmental factor or a physiological change triggers the onset of the disease. We report the first case of aHUS in a pregnant woman with chronic kidney disease.