IGHA1 and Nephropathy: In addition, aberrantly glycosylated IgA1 acts as an autoantigen and forms IgG autoantibodies against Gal-deficient IgA1 molecules; these bind to the aberrantly glycosylated IgA1 molecules to form circulating immune complexes that are deposited in the glomerular mesangium, thereby causing kidney damage (17).