Disease-associated IgA O-glycosylation changes have been demonstrated in several IgA-related diseases, such as IgA nephropathy, Henoch-Schönlein purpura, Wiskott-Aldrich syndrome and X-linked thrombocytopenia, for which decreased levels of Gal on the O-glycans were observed [27–29]. This evidence concerns the gene CD79A and Henoch-Schoenlein purpura.