Anti-GBM disease with positive serum anti-GBM antibodies but negative IgG deposition: A case report.

Anti-glomerular basement membrane antibodies are significantly specific for detecting anti-glomerular basement membrane disease. These antibodies are typically targeted against the non-collagenous (NC1) domain of the alpha 3 chain of type IV collagen and, to a lesser extent, the α4(IV) or α5(IV) chains, which create a triple-helical structure in the glomerular basement membrane. The modification of the hexameric structure of NC1 (α3(IV)) results in the exposure of new epitopes, leading to an immune reaction and the subsequent deposition of linear antibodies along the glomerular basement membrane, culminating in crescentic glomerulonephritis. Anti-glomerular basement membrane antibodies that are positive are believed to be pathogenic and capable of binding to the glomerular basement membrane in vivo, particularly in the context of rapidly progressive glomerulonephritis. Herein, we present a patient with positive serum anti-glomerular basement membrane antibodies but negative IgG deposition. The current findings are significant for raising physicians' awareness of the probable errors in detecting anti-glomerular basement membrane antibody disease as a possible cause of irreversible kidney failure.