Glycosylation is very important for IgA immune function: aberrantly glycosylated IgA forms are associated with autoimmune diseases such as IgA nephropathy, IgA vasculitis, and rheumatoid arthritis (24); glycans attached to N459 can interact directly with and neutralize certain viruses (25); and finally, glycans impact the interactions of S-IgA with commensal microorganisms, thus influencing the microbiota composition and gut homeostasis (26, 27). The gene discussed is CD79A; the disease is Henoch-Schoenlein purpura.