These results suggest that serum levels of DNAJB9 could be a valuable marker to predict FGN, with the potential to complement kidney biopsy for the diagnosis of FGN.
This advances our understanding of DNAJB9 as a biomarker in FGN and reframes questions about pathogenesis and potential clinical applications of DNAJB9 serum testing.
Immunohistochemical studies confirmed the high sensitivity and specificity of DnaJ homolog subfamily B member 9 for this disease; dual immunofluorescence showed its colocalization with IgG in glomeruli; and immunoelectron microscopy revealed its localization to individual fibrils of fibrillary glomerulonephritis.
The diagnosis should be suspected when the kidney biopsy shows fibrillary glomerulonephritis with negative staining for immunoglobulin light chains and DNAJB9; the diagnosis can be confirmed using immunochemical and molecular studies.
DNAJB9, a recently discovered proteomic marker for fibrillary GN, was detected using mass spectrometry in all cases of fibrillary GN regardless of congophilia and was absent in cases of amyloidosis and in healthy individuals.