MYOM2 and monoclonal gammopathy: Non-malignant monoclonal gammopathy is differentiated from malignant monoclonal gammopathy by a lower level of serum M protein, low or undetectable level of M protein in the urine, absence of other signs of systemic disease such as lytic bone lesions, anemia, hypercalcemia, or renal insufficiency, and fewer than 10% plasma cells or absence of lymphoid aggregates in the bone marrow.