As published for monoclonal IgGs, the sialylation level of unseparated, total IgAs, assessed in serum, expressed in % sialylation, was lower for MGUS and myeloma patients with a monoclonal IgA than for healthy volunteers (41.2 vs. 63.4%, respectively; ***p < 0.0001, Mann–Whitney U-test) (Figure 5A) (12, 21). Here, CD79A is linked to plasma cell myeloma.