Abstract: SA-PO0755
C3 Glomerulopathy Associated with a Monoclonal IgA κ
Session Information
- Glomerular Diseases: Lupus Nephritis, Monoclonal Gammopathy-Related Disease, and Transplantation
October 24, 2026 | Location: Exhibit Hall A, Convention Center
Abstract Time: 10:00 AM - 12:00 PM
Category: Glomerular Diseases
- 1402 Glomerular Diseases: Clinical, Outcomes, and Therapeutics
Authors
- Zhang, Chi, The University of British Columbia Faculty of Medicine, Vancouver, British Columbia, Canada
- Zhang, Grace Joyce, The University of British Columbia, Vancouver, British Columbia, Canada
- Riazy, Maziar, The University of British Columbia, Vancouver, British Columbia, Canada
Introduction
Monoclonal Ig may play a causal role in C3GN by impairing regulation of the AP of complement.IgG κ is believed to be the most frequently mIg driving C3 GN. In this case, we reported a patient with IgA κ potentially causing C3GN and had a good response to typical anticlonal therapy MYDARCBDF.
Case Description
A 62 year old white male, with history of Sneddon-Wilkinson disease, Ig A κ 5.5 g /l (pre chemotherapy), MGUS, proteinuria 3.8 g per day, large amount of microscopic hematuria, presented to renal service with progressively worsening eGFR (90s-37 ml/min) in 2 years. He takes Dapsone and clobetasol ointment for his skin lesion (Sneddon-Wilkinson) with good response. Pre biopsy data:
eGFR 43, IgA κ5.5 g/l, all serology were negative, C3 0.73 g/l ( 0.87-2.0g/l), C4 normal 0.43g/l.Bone marrow biopsy: 8-10 % Ig A κ plasma cells.Kidney biopsy shows C3GN see Fig 1 and legend. Patient started chemotherapy1 month post biopsy. Cycle 1 MYDARCBDF (CYCLOPHOSPHAMIDE 300MG PO weekly, bortezomib 2.7mg sq weekly, dexamethasone 20mg q weekly, daratumumab 1800 mg sq weekly). After 13 cycles, patient felt better. Good energy level. C3 normalized, eGFR went up to 54 ml/min. His IgA κ level also came down to 0.9 g/l. free light chains κ/λ ratio 8.6 no significant changes. Proteinuria improved to 0.88g/d..
Discussion
We suspect this case CRF is from C3GN which is likely related to IgA κ, which is associated to Sneddon- Wilkinson disease. As far as we know, this is the first report about such association. And C3GN caused by IgAκ is treatable.
Light microscopy shows a glomerulus with mesangial and endocapillary hypercellularity, segmental MPGN pattern of injury, and wedge-shaped attachment of the tuft to adjacent bowman’s capsule. The electron microscopy shows mesangial and capillary wall immune deposits. By direct immunofluorescence, there is strong mesangial and capillary wall staining for C3 while no significant staining was seen with the other immunoreactants. Immunofluorescence performed on paraffin–embedded tissue, after proteinase digestion, showed no unmasking of the deposits for IgA, κ and λ light chains.