Thrombotic microangiopathy and smoldering multiple myeloma after kidney transplant in a patient with MCP mutation

• Published in: Journal of Onco-Nephrology 2022-06, Vol.6 (1-2), p.52-55
• Main Authors: Almenara Tejederas, Marina, De la Torre Corona, Laura, García, Fabiola Alonso, Pérez, María Ángeles Rodríguez, Pérez, Rocío Cabrera, Lazo, Mercedes Salgueira
• Format: Article
• Language: English
• ISSN: 2399-3693; 2399-3707
• DOI: 10.1177/23993693211062611

The most frequent cause of atypical hemolytic uremic syndrome (aHUS) is defective regulation of complement activation because of genetic anomalies. We present the case of 53-year-old man with a kidney transplant and stabilized kidney function (creatinine 2.5 mg/dL; proteinuria 0.4 g/24 h) with mycophenolate/tacrolimus/prednisone who was diagnosed of Thrombotic Microangiopathy (TMA). This diagnosis was associated with creatinine and proteinuria rise (3 mg/dL; 2.4 g/24 h) and a new monoclonal IgA/lambda component. Renal biopsy showed membranoproliferative glomerulonephritis; a pathogenic variant in the Membrane cofactor protein (MCP) gene with a polymorphism ggaac, typically associated to secondary aHUS, was identified. We suspected that immunoglobulin could be acting as a trigger for TMA in a genetically susceptible patient, so “clone-directed” therapy with bortezomib and dexamethasone was initiated.