For many of these samples, the co-migration of the monoclonal IgA protein with other serum proteins in β-region (i.e., transferrin) [39] prevents accurate quantitation of the M-spike by SPE; for this reason, the IMWG recognize the limitations of electrophoresis, and state that “For several patients, especially with IgA or IgD myeloma, nephelometric quantitation of serum immunoglobulin is necessary” [37]. Here, CD79A is linked to plasma cell myeloma.