In IgA nephropathy (IgAN), there is dysregulation of the IgA response to a wide range of
antigens. The dysregulation promotes synthesis of polymeric IgA1 (pIgA1) with
physicochemical characteristics that favor mesangial deposition, including altered O-
glycosylation of the hinge region. This may be the synthesis of IgA in the systemic
compartment, which has the phenotype of mucosal IgA. There is not a change in IgA1
structure to an entirely abnormal form; rather, there is a shift that results in a proportional …