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Abstract: SA-PO669

A Case of an IgA Variant of Anti-Glomerular Basement Membrane Disease

Session Information

Category: Glomerular Diseases

  • 1302 Glomerular Diseases: Immunology and Inflammation

Authors

  • Hamill, Mairead, Tallaght University Hospital, Dublin, Dublin, Ireland
  • Harrington, Ian, Tallaght University Hospital, Dublin, Dublin, Ireland
  • Madden, Michelle, Tallaght University Hospital, Dublin, Dublin, Ireland
  • Ward, Francis, Tallaght University Hospital, Dublin, Dublin, Ireland
Introduction

Anti-GBM disease is a rapidly progressive glomerulonephritis. Pathogenesis is generally attributed to circulating IgG autoantibodies against cryptic epitopes in the NC1 domain of the alpha-3 chain of type IV collagen. It is a rare disease with a grave prognosis. Atypical anti-GBM disease has been described as a variant characterised by linear staining of GBM by IgG, IgM or IgA, in the absence of circulating anti-GBM autoantibodies. Here we report a case of an IgA variant of atypical anti-GBM disease.

Case Description

A 77-year old Caucasian female presented with malaise, and pyrexia on a background of chronic obstructive pulmonary disease. She had recently recovered from COVID-19. On presentation, she had anuric AKINIII (creatinine: 10.2 mg/dL) with previously normal function. On imaging, chest was clear and there was no obstruction. Urine microscopy revealed microhaematuria and proteinuria was quantified at 288mg/mmol. Complement studies and immunoglobulins were normal. HIV, hepatitis B and C virology were negative. Serum anti-GBM and anti-neutrophil cytoplasmic antibodies (ab) were negative. Kidney biopsy revealed extensive crescentic glomerulonephritis, with moderate interstitial fibrosis. GBM thickening was noted. On IF, linear staining for IgA (2+) and C3 was seen in capillary loops. EM did not identify immune complex deposition disease. Immunosuppression with prednisolone, cyclophosphamide and plasmapheresis was initiated without success. Serum IgA anti-GBM ab was negative. She remains dialysis dependent.

Discussion

The limited available literature suggests that biopsy-proven IgA variant anti-GBM disease, with undetectable serum anti-GBM ab, is an extremely rare presentation and that conventional therapies are rarely successful. Early diagnosis has an impact on prognosis in anti-GBM disease and, given widespread use of IgG anti-GBM ab assays, atypical cases may have treatment initiated later with devastating repercussions. This case illustrates the importance of prompt biopsy and need for increased awareness of atypical anti-GBM disease presentations.