Besides specific affinity for autoantigens participated in coagulation process, antibody activities of monoclonal immunoglobulin reported in cases were highly varied, like IgM acting as anti-myelin-associated glycoprotein (MAG) antibodies in MGUS associated with peripheral neuropathy [12], IgM and IgG against transferrin in MGUS associated with transferrin-immune complex disease (TICD) [13] and IgG as antibodies against the CUB1-2 domains of ADAMTS13 in a MGUS patient associated with thrombotic thrombocytopenic purpura [14]. The gene discussed is MAG; the disease is thrombotic thrombocytopenic purpura.