Heterogeneity of Aberrant O-Glycosylation of IgA1 in IgA Nephropathy

IgA nephropathy (IgAN), a frequent cause of end-stage renal disease, is an autoimmune disease wherein immune complexes consisting of IgA1 with galactose-deficient O-glycans (Gd-IgA1; autoantigen) and anti-glycan autoantibodies deposit in the glomeruli and induce renal injury. Serum IgA1 has three to six clustered O-glycans, some of which may be deficient in galactose and thus expose terminal or sialylated N-acetylgalactosamine. Patients with IgAN usually have elevated serum levels of Gd-IgA1. The mechanisms involved in production of Gd-IgA1 are not fully understood.