The study of immunoglobulin G subtypes constituting immune deposits present in membranous nephropathy is useful to guide diagnosis. IgG4 deposits are more often seen in primitive forms of membranous nephropathy due to autoantibody (anti-phospholipase A2 receptor in a majority of cases). These deposits are polytypic. In secondary forms, deposits are constituted of IgG1, IgG2 and IgG3. We report the case of a 52-year-old woman whose renal biopsy, done for glomerular proteinuria, shows membranous nephropathy with monotypic IgG4 deposits with no overt hematologic malignancy and no anti-PLA2R antibodies.
Keywords: Gammapathie monoclonale de signification rénale; Glomérulonéphrite extramembraneuse; IgG4; IgG4 monotypique; Immunoglobulin G subtypes; Membranous nephropathy; Monoclonal gammapathy of renal significance; Sous-type d’immunoglobuline G.
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