According to the International Myeloma Working Group (IMWG) criteria, SMM is distinguished from MGUS by the level of M-protein ≥ 3 g/dL or urinary M protein ≥ 500 mg/24 h and/or the percentage of bone marrow plasma cells (≥ 10% - <60%). This evidence concerns the gene MYOM2 and plasma cell myeloma.