A Case Report of C3 Glomerulonephritis: A Rare and Poorly Understood Disease

Introduction: Cases of C3 Glomerulopathies are rare, with an incidence of one to three cases per million. The pathogenesis is caused by excessive activation of the alternative complement pathway that leads to dense deposit formation leading GN. The disease is often caused by autoantibodies that target C3 or C5 convertase, although the pathophysiology remains poorly understood. Currently, there are no disease-specific treatments available. Immunosuppressive agents can be helpful but are not universally curative or effective. The progression to end-stage-renal disease occurs in 50% of adults in 10 years. This is a case of a middle-aged female without significant medical history who presented after a mechanical fall with uremic symptoms and was diagnosed with rapidly progressive C3GN. Case Description: 64-year-old female presented to the hospital after have a mechanical fall one week prior, complaining of visual hallucinations, nausea, and decreased appetite. She had a prior history notable for schizoaffective disorder, bipolar, and prior DVT. Lab work on presentation was significant for severe AKI (Cr of 7.1 from a baseline of 1.0), normochromic normocytic anemia, severe metabolic acidosis, and hypoalbuminemia. Initial UA with 3+ proteinuria, innumerable RBCs, 20-30 WBCs with multiple hyaline case. Serologies for glomerulonephritis work up were significant for low C3 (56) and reactive hepatitis B core total antibody Patient underwent a renal biopsy that showed diffuse crescenteric GN with severe activity and moderate chronicity concerning C3 glomerulopathy. She subsequently underwent bone marrow biopsy that ruled out monoclonal gammopathy of renal significance. She underwent an unremarkable genetic renal panel that tested 13 genes implicated in C3GN. The patient was initiated on solumedrol and mycophenolate but unfortunately did not have renal recovery and became dialysis dependent. Discussion: C3GN are extremely rare conditions from underlying complement dysregulation. The diagnosis merely relies on renal biopsy immunofluorescence, light microscopy, and complement biomarker findings. Autoantibodies and monoclonal gammopathy are most associated with complement dysregulation, however genetic variants are a potential cause. An imperative need remains for studying the history of C3GN to better understand pathophysiology and genetic biomarkers to establish an optimal treatment through clinical trails.