CD40LG and monoclonal gammopathy: Other ancillary tests confirmed the IgM monoclonal gammopathy (7.3 g/L; N < 1.7) with a Kappa light chain (52.5 mg/L; N < 19.4) and a high level of antimyelin-associated glycoprotein (MAG) antibodies (>70,000 Bühlmann Titer Unit).