The IgG isotype was most commonly seen in 90 patients (59%), the IgA isotype in 26 patients (17%), light chain–only disease in 27 patients (18%), nonsecretory MM or no definite/quantifiable monoclonal peak on SPEP with immunofixation electrophoresis (IFE) in 6 patients, and 2 patients had the IgM isotype. This evidence concerns the gene CD79A and Miyoshi myopathy.