Detection of M-protein, a monoclonal immunoglobulin produced by malignant plasma cells in the bone marrow, is crucial in multiple myeloma (MM) diagnostics, treatment, and follow-up.1 M-protein is most commonly detected and quantified with serum protein electrophoresis (SPEP) using patient serum or urine as the starting material for analysis. This evidence concerns the gene MYOM2 and AL amyloidosis.