Definition:

Primary IgA nephropathy is an immune-complex-mediated glomerulonephritis defined immunohistologically by the presence of glomerular IgA deposits accompanied by a variety of histopathologic lesions. It is known to be the most prevalent primary chronic glomerular disease worldwide. Because of the critical interaction between an intrinsic antigen (galactose-deficient IgA1) and circulating anti-glycan antibodies, IgA nephropathy can be considered an autoimmune disease. Since the features of IgA nephropathy identified by light microscopy are nonspecific, immunofluorescence or immunoperoxidase studies demonstrating a predominant deposition of IgA are essential to establish a definitive diagnosis of IgA nephropathy. Genetic factors undoubtedly influence the pathogenesis of IgA nephropathy. Genomewide association studies have identified common susceptibility loci in the absence of a priori mechanistic hypotheses.