Authors: Jacob Welch , Reem Alshiyyab , Kevin Pargeter

Abstract

Background: Atypical hemolytic uremic syndrome (aHUS) is a rare, life-threatening thrombotic microangiopathy (TMA) primarily driven by uncontrolled activation of the alternative complement pathway. Genetic mutations in complement regulatory proteins are identified in the majority of cases, highlighting the hereditary nature of the disease.

Case Presentation: This report is the case of a male in his late 40s with a solitary kidney (following a prior living donor nephrectomy for his father) who presented to an outpatient nephrology clinic with worsening renal function and thrombocytopenia. After ruling out underlying secondary causes, genetic testing confirmed a mutation associated with aHUS. Despite the nephrologist prescribing targeted anti-complement therapy, insurance authorization was denied. The patient was referred to a specialty clinic and is currently undergoing close monitoring to determine if his clinical state warrants treatment with complement inhibitor medication.

Conclusion: This case highlights the clinical complexities of managing adult-onset hereditary aHUS, particularly in vulnerable patients with a solitary kidney. It underscores the challenges of treatment accessibility, the significance of family history in uncovering genetic predispositions, and the necessity of vigilant monitoring as disease penetrance increases with age.

Keywords: Atypical hemolytic uremic syndrome, thrombotic microangiopathy, solitary kidney, complement factor H, genetic mutation.